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Lasaponara S, Scozia G, Lozito S, Pinto M, Conversi D, Costanzi M, Vriens T, Silvetti M, Doricchi F. Temperament and probabilistic predictive coding in visual-spatial attention. Cortex 2024; 171:60-74. [PMID: 37979232 DOI: 10.1016/j.cortex.2023.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/21/2023] [Accepted: 10/16/2023] [Indexed: 11/20/2023]
Abstract
Cholinergic (Ach), Noradrenergic (NE), and Dopaminergic (DA) pathways play an important role in the regulation of spatial attention. The same neurotransmitters are also responsible for inter-individual differences in temperamental traits. Here we explored whether biologically defined temperamental traits determine differences in the ability to orient spatial attention as a function of the probabilistic association between cues and targets. To this aim, we administered the Structure of Temperament Questionnaire (STQ-77) to a sample of 151 participants who also performed a Posner task with central endogenous predictive (80 % valid/20 % invalid) or non-predictive cues (50 % valid/50 % invalid). We found that only participants with high scores in Plasticity and Intellectual Endurance showed a selective abatement of attentional costs with non-predictive cues. In addition, stepwise regression showed that costs in the non-predictive condition were negatively predicted by scores in Plasticity and positively predicted by scores in Probabilistic Thinking. These results show that stable temperamental characteristics play an important role in defining the inter-individual differences in attentional behaviour, especially in the presence of different probabilistic organisations of the sensory environment. These findings emphasize the importance of considering temperamental and personality traits in social and professional environments where the ability to control one's attention is a crucial functional skill.
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Affiliation(s)
- Stefano Lasaponara
- Department of Psychology, "Sapienza" University of Rome, Italy; IRCCS Fondazione Santa Lucia, Rome, Italy.
| | - Gabriele Scozia
- Department of Psychology, "Sapienza" University of Rome, Italy; IRCCS Fondazione Santa Lucia, Rome, Italy; PhD Programme in Behavioural Neuroscience, "Sapienza" University of Rome, Italy
| | - Silvana Lozito
- Department of Psychology, "Sapienza" University of Rome, Italy; IRCCS Fondazione Santa Lucia, Rome, Italy; PhD Programme in Behavioural Neuroscience, "Sapienza" University of Rome, Italy
| | - Mario Pinto
- Department of Psychology, "Sapienza" University of Rome, Italy; IRCCS Fondazione Santa Lucia, Rome, Italy
| | - David Conversi
- Department of Psychology, "Sapienza" University of Rome, Italy
| | - Marco Costanzi
- Department of Human Science, LUMSA University, Rome, Italy
| | - Tim Vriens
- Computational and Translational Neuroscience Laboratory (CTNLab), Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy
| | - Massimo Silvetti
- Computational and Translational Neuroscience Laboratory (CTNLab), Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy
| | - Fabrizio Doricchi
- Department of Psychology, "Sapienza" University of Rome, Italy; IRCCS Fondazione Santa Lucia, Rome, Italy.
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2
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Hassani S, Neumann A, Russell J, Jones C, Womelsdorf T. M 1-selective muscarinic allosteric modulation enhances cognitive flexibility and effective salience in nonhuman primates. Proc Natl Acad Sci U S A 2023; 120:e2216792120. [PMID: 37104474 PMCID: PMC10161096 DOI: 10.1073/pnas.2216792120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 03/21/2023] [Indexed: 04/28/2023] Open
Abstract
Acetylcholine (ACh) in cortical neural circuits mediates how selective attention is sustained in the presence of distractors and how flexible cognition adjusts to changing task demands. The cognitive domains of attention and cognitive flexibility might be differentially supported by the M1 muscarinic acetylcholine receptor (mAChR) subtype. Understanding how M1 mAChR mechanisms support these cognitive subdomains is of highest importance for advancing novel drug treatments for conditions with altered attention and reduced cognitive control including Alzheimer's disease or schizophrenia. Here, we tested this question by assessing how the subtype-selective M1 mAChR positive allosteric modulator (PAM) VU0453595 affects visual search and flexible reward learning in nonhuman primates. We found that allosteric potentiation of M1 mAChRs enhanced flexible learning performance by improving extradimensional set shifting, reducing latent inhibition from previously experienced distractors and reducing response perseveration in the absence of adverse side effects. These procognitive effects occurred in the absence of apparent changes of attentional performance during visual search. In contrast, nonselective ACh modulation using the acetylcholinesterase inhibitor (AChEI) donepezil improved attention during visual search at doses that did not alter cognitive flexibility and that already triggered gastrointestinal cholinergic side effects. These findings illustrate that M1 mAChR positive allosteric modulation enhances cognitive flexibility without affecting attentional filtering of distraction, consistent with M1 activity boosting the effective salience of relevant over irrelevant objects specifically during learning. These results suggest that M1 PAMs are versatile compounds for enhancing cognitive flexibility in disorders spanning schizophrenia and Alzheimer's diseases.
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Affiliation(s)
- Seyed A. Hassani
- Department of Psychology, Vanderbilt University, Nashville, TN37240
| | - Adam Neumann
- Department of Psychology, Vanderbilt University, Nashville, TN37240
| | - Jason Russell
- Department of Pharmacology, Vanderbilt University, Nashville, TN37240
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN37240
| | - Carrie K. Jones
- Department of Pharmacology, Vanderbilt University, Nashville, TN37240
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN37240
| | - Thilo Womelsdorf
- Department of Psychology, Vanderbilt University, Nashville, TN37240
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN37240
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3
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Tu G, Halawa A, Yu X, Gillman S, Takehara-Nishiuchi K. Outcome-Locked Cholinergic Signaling Suppresses Prefrontal Encoding of Stimulus Associations. J Neurosci 2022; 42:4202-4214. [PMID: 35437276 PMCID: PMC9121825 DOI: 10.1523/jneurosci.1969-21.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 02/11/2022] [Accepted: 03/01/2022] [Indexed: 11/21/2022] Open
Abstract
Acetylcholine (ACh) is thought to control arousal, attention, and learning by slowly modulating cortical excitability and plasticity. Recent studies, however, discovered that cholinergic neurons emit precisely timed signals about the aversive outcome at millisecond precision. To investigate the functional relevance of such phasic cholinergic signaling, we manipulated and monitored cholinergic terminals in the mPFC while male mice associated a neutral conditioned stimulus (CS) with mildly aversive eyelid shock (US) over a short temporal gap. Optogenetic inhibition of cholinergic terminals during the US promoted the formation of the CS-US association. On the contrary, optogenetic excitation of cholinergic terminals during the US blocked the association formation. The bidirectional behavioral effects paralleled the corresponding change in the expression of an activity-regulated gene, c-Fos in the mPFC. In contrast, optogenetic inhibition of cholinergic terminals during the CS impaired associative learning, whereas their excitation had marginal effects. In parallel, photometric recording from cholinergic terminals in the mPFC revealed strong innate phasic responses to the US. With subsequent CS-US pairings, cholinergic terminals weakened the responses to the US while developing strong responses to the CS. The across-session changes in the CS- and US-evoked terminal responses were correlated with associative memory strength. These findings suggest that phasic cholinergic signaling in the mPFC exerts opposite effects on aversive associative learning depending on whether it is emitted by the outcome or the cue.SIGNIFICANCE STATEMENT Drugs compensating for the decline of acetylcholine (ACh) are used for cognitive impairment, such as Alzheimer's disease. However, their beneficial effects are limited, demanding new strategies based on better understandings of how ACh modulates cognition. Here, we report that by manipulating ACh signals in the mPFC, we can control the strength of aversive associative learning in mice. Specifically, the suppression of ACh signals during an aversive outcome facilitated its association with a preceding cue. In contrast, the suppression of ACh signals during the cue impaired learning. Considering that this paradigm depends on the brain regions affected in Alzheimer's disease, our findings indicate that precisely timed control of ACh signals is essential to refine ACh-based strategies for cognitive enhancement.
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Affiliation(s)
- Gaqi Tu
- Department of Psychology, University of Toronto, Toronto, Ontario M5S 3G3, Canada
- Collaborative Program in Neuroscience, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Adel Halawa
- Human Biology Program, University of Toronto, Toronto, Ontario M5S 3J6, Canada
| | - Xiaotian Yu
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Samuel Gillman
- Department of Psychology, University of Toronto, Toronto, Ontario M5S 3G3, Canada
- Human Biology Program, University of Toronto, Toronto, Ontario M5S 3J6, Canada
| | - Kaori Takehara-Nishiuchi
- Department of Psychology, University of Toronto, Toronto, Ontario M5S 3G3, Canada
- Collaborative Program in Neuroscience, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
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4
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Avram M, Grothe MJ, Meinhold L, Leucht C, Leucht S, Borgwardt S, Brandl F, Sorg C. Lower cholinergic basal forebrain volumes link with cognitive difficulties in schizophrenia. Neuropsychopharmacology 2021; 46:2320-2329. [PMID: 34188186 PMCID: PMC8580980 DOI: 10.1038/s41386-021-01070-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 06/01/2021] [Accepted: 06/12/2021] [Indexed: 02/06/2023]
Abstract
A potential pathophysiological mechanism of cognitive difficulties in schizophrenia is a dysregulated cholinergic system. Particularly, the cholinergic basal forebrain nuclei (BFCN), the source of cortical cholinergic innervation, support multiple cognitive functions, ranging from attention to decision-making. We hypothesized that BFCN structural integrity is altered in schizophrenia and associated with patients' attentional deficits. We assessed gray matter (GM) integrity of cytoarchitectonically defined BFCN region-of-interest in 72 patients with schizophrenia and 73 healthy controls, matched for age and gender, from the COBRE open-source database, via structural magnetic resonance imaging (MRI)-based volumetry. MRI-derived measures of GM integrity (i.e., volumes) were linked with performance on a symbol coding task (SCT), a paper-pencil-based metric that assesses attention, by correlation and mediation analysis. To assess the replicability of findings, we repeated the analyses in an independent dataset comprising 26 patients with schizophrenia and 24 matched healthy controls. BFCN volumes were lower in patients (t(139)=2.51, p = 0.01) and significantly associated with impaired SCT performance (r = 0.31, p = 0.01). Furthermore, lower BFCN volumes mediated the group difference in SCT performance. When including global GM volumes, which were lower in patients, as covariates-of-no-interest, these findings disappeared, indicating that schizophrenia did not have a specific effect on BFCN relative to other regional volume changes. We replicated these findings in the independent cohort, e.g., BFCN volumes were lower in patients and mediated patients' impaired SCT performance. Results demonstrate lower BFCN volumes in schizophrenia, which link with patients' attentional deficits. Data suggest that a dysregulated cholinergic system might contribute to cognitive difficulties in schizophrenia via impaired BFCN.
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Affiliation(s)
- Mihai Avram
- Department of Psychiatry and Psychotherapy, Schleswig Holstein University Hospital, University of Lübeck, Lübeck, 23538, Germany.
| | - Michel J. Grothe
- grid.414816.e0000 0004 1773 7922Unidad de Trastornos del Movimiento, Servicio de Neurología y Neurofisiología Clínica, Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Sevilla, Spain
| | - Lena Meinhold
- grid.6936.a0000000123222966TUM-NIC Neuroimaging Center, Technical University of Munich, School of Medicine, Munich, 81675 Germany
| | - Claudia Leucht
- grid.6936.a0000000123222966Department of Psychiatry and Psychotherapy, Technical University of Munich, School of Medicine, Munich, 81675 Germany
| | - Stefan Leucht
- grid.6936.a0000000123222966Department of Psychiatry and Psychotherapy, Technical University of Munich, School of Medicine, Munich, 81675 Germany
| | - Stefan Borgwardt
- grid.4562.50000 0001 0057 2672Department of Psychiatry and Psychotherapy, Schleswig Holstein University Hospital, University of Lübeck, Lübeck, 23538 Germany
| | - Felix Brandl
- grid.6936.a0000000123222966TUM-NIC Neuroimaging Center, Technical University of Munich, School of Medicine, Munich, 81675 Germany ,grid.6936.a0000000123222966Department of Psychiatry and Psychotherapy, Technical University of Munich, School of Medicine, Munich, 81675 Germany ,grid.6936.a0000000123222966Department of Neuroradiology, Technical University of Munich, School of Medicine, Munich, 81675 Germany
| | - Christian Sorg
- grid.6936.a0000000123222966TUM-NIC Neuroimaging Center, Technical University of Munich, School of Medicine, Munich, 81675 Germany ,grid.6936.a0000000123222966Department of Psychiatry and Psychotherapy, Technical University of Munich, School of Medicine, Munich, 81675 Germany ,grid.6936.a0000000123222966Department of Neuroradiology, Technical University of Munich, School of Medicine, Munich, 81675 Germany
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5
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Koulousakis P, Andrade P, Visser-Vandewalle V, Sesia T. The Nucleus Basalis of Meynert and Its Role in Deep Brain Stimulation for Cognitive Disorders: A Historical Perspective. J Alzheimers Dis 2020; 69:905-919. [PMID: 31104014 DOI: 10.3233/jad-180133] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The nucleus basalis of Meynert (nbM) was first described at the end of the 19th century and named after its discoverer, Theodor Meynert. The nbM contains a large population of cholinergic neurons that project their axons to the entire cortical mantle, the olfactory tubercle, and the amygdala. It has been functionally associated with the control of attention and maintenance of arousal, both key functions for appropriate learning and memory formation. This structure is well-conserved across vertebrates, although its degree of organization varies between species. Since early in the investigation of its functional and pathological significance, its degeneration has been linked to various major neuropsychiatric disorders. For instance, Lewy bodies, a hallmark in the diagnosis of Parkinson's disease, were originally described in the nbM. Since then, its involvement in other Lewy body and dementia-related disorders has been recognized. In the context of recent positive outcomes following nbM deep brain stimulation in subjects with dementia-associated disorders, we review the literature from an historical perspective focusing on how the nbM came into focus as a promising therapeutic option for patients with Alzheimer's disease. Moreover, we will discuss what is needed to further develop and widely implement this approach as well as examine novel medical indications for which nbM deep brain stimulation may prove beneficial.
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Affiliation(s)
- Philippos Koulousakis
- Department of Stereotactic and Functional Neurosurgery, University Hospital of Cologne, Germany.,European Graduate School of Neuroscience, Maastricht, The Netherlands
| | - Pablo Andrade
- Department of Neurosurgery, University Hospital of Cologne, Germany.,European Graduate School of Neuroscience, Maastricht, The Netherlands
| | - Veerle Visser-Vandewalle
- Department of Stereotactic and Functional Neurosurgery, University Hospital of Cologne, Germany.,European Graduate School of Neuroscience, Maastricht, The Netherlands
| | - Thibaut Sesia
- Department of Stereotactic and Functional Neurosurgery, University Hospital of Cologne, Germany.,European Graduate School of Neuroscience, Maastricht, The Netherlands
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6
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Záborszky L, Gombkoto P, Varsanyi P, Gielow MR, Poe G, Role LW, Ananth M, Rajebhosale P, Talmage DA, Hasselmo ME, Dannenberg H, Minces VH, Chiba AA. Specific Basal Forebrain-Cortical Cholinergic Circuits Coordinate Cognitive Operations. J Neurosci 2018; 38:9446-9458. [PMID: 30381436 PMCID: PMC6209837 DOI: 10.1523/jneurosci.1676-18.2018] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 09/11/2018] [Accepted: 09/12/2018] [Indexed: 11/21/2022] Open
Abstract
Based on recent molecular genetics, as well as functional and quantitative anatomical studies, the basal forebrain (BF) cholinergic projections, once viewed as a diffuse system, are emerging as being remarkably specific in connectivity. Acetylcholine (ACh) can rapidly and selectively modulate activity of specific circuits and ACh release can be coordinated in multiple areas that are related to particular aspects of cognitive processing. This review discusses how a combination of multiple new approaches with more established techniques are being used to finally reveal how cholinergic neurons, together with other BF neurons, provide temporal structure for behavior, contribute to local cortical state regulation, and coordinate activity between different functionally related cortical circuits. ACh selectively modulates dynamics for encoding and attention within individual cortical circuits, allows for important transitions during sleep, and shapes the fidelity of sensory processing by changing the correlation structure of neural firing. The importance of this system for integrated and fluid behavioral function is underscored by its disease-modifying role; the demise of BF cholinergic neurons has long been established in Alzheimer's disease and recent studies have revealed the involvement of the cholinergic system in modulation of anxiety-related circuits. Therefore, the BF cholinergic system plays a pivotal role in modulating the dynamics of the brain during sleep and behavior, as foretold by the intricacies of its anatomical map.
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Affiliation(s)
- Laszlo Záborszky
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark 07102,
| | - Peter Gombkoto
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark 07102
| | - Peter Varsanyi
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark 07102
| | - Matthew R Gielow
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark 07102
| | - Gina Poe
- Department of Integrative Biology and Physiology, University of California, Los Angeles 90095
| | - Lorna W Role
- Department of Neurobiology and Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York 11794
| | - Mala Ananth
- Program in Neuroscience and Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York 11794
| | - Prithviraj Rajebhosale
- Program in Neuroscience and Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York 11794
| | - David A Talmage
- Department of Pharmacological Sciences and Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York 11794
| | - Michael E Hasselmo
- Center for Systems Neuroscience and Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts 02215, and
| | - Holger Dannenberg
- Center for Systems Neuroscience and Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts 02215, and
| | - Victor H Minces
- Department of Cognitive Science, University of California, San Diego 92093
| | - Andrea A Chiba
- Department of Cognitive Science, University of California, San Diego 92093
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7
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Galvin VC, Arnsten AFT, Wang M. Evolution in Neuromodulation-The Differential Roles of Acetylcholine in Higher Order Association vs. Primary Visual Cortices. Front Neural Circuits 2018; 12:67. [PMID: 30210306 PMCID: PMC6121028 DOI: 10.3389/fncir.2018.00067] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 08/06/2018] [Indexed: 11/29/2022] Open
Abstract
This review contrasts the neuromodulatory influences of acetylcholine (ACh) on the relatively conserved primary visual cortex (V1), compared to the newly evolved dorsolateral prefrontal association cortex (dlPFC). ACh is critical both for proper circuit development and organization, and for optimal functioning of mature systems in both cortical regions. ACh acts through both nicotinic and muscarinic receptors, which show very different expression profiles in V1 vs. dlPFC, and differing effects on neuronal firing. Cholinergic effects mediate attentional influences in V1, enhancing representation of incoming sensory stimuli. In dlPFC ACh plays a permissive role for network communication. ACh receptor expression and ACh actions in higher visual areas have an intermediate profile between V1 and dlPFC. This changing role of ACh modulation across association cortices may help to illuminate the particular susceptibility of PFC in cognitive disorders, and provide therapeutic targets to strengthen cognition.
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Affiliation(s)
- Veronica C Galvin
- Department of Neuroscience, Yale University, New Haven, CT, United States
| | - Amy F T Arnsten
- Department of Neuroscience, Yale University, New Haven, CT, United States
| | - Min Wang
- Department of Neuroscience, Yale University, New Haven, CT, United States
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8
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Abstract
Notwithstanding tremendous research efforts, the cause of Alzheimer's disease (AD) remains elusive and there is no curative treatment. The cholinergic hypothesis presented 35 years ago was the first major evidence-based hypothesis on the etiology of AD. It proposed that the depletion of brain acetylcholine was a primary cause of cognitive decline in advanced age and AD. It relied on a series of observations obtained in aged animals, elderly, and AD patients that pointed to dysfunctions of cholinergic basal forebrain, similarities between cognitive impairments induced by anticholinergic drugs and those found in advanced age and AD, and beneficial effects of drugs stimulating cholinergic activity. This review revisits these major results to show how this hypothesis provided the drive for the development of anticholinesterase inhibitor-based therapies of AD, the almost exclusively approved treatment in use despite transient and modest efficacy. New ideas for improving cholinergic therapies are also compared and discussed in light of the current revival of the cholinergic hypothesis on the basis of two sets of evidence from new animal models and refined imagery techniques in humans. First, human and animal studies agree in detecting signs of cholinergic dysfunctions much earlier than initially believed. Second, alterations of the cholinergic system are deeply intertwined with its reactive responses, providing the brain with efficient compensatory mechanisms to delay the conversion into AD. Active research in this field should provide new insight into development of multitherapies incorporating cholinergic manipulation, as well as early biomarkers of AD enabling earlier diagnostics. This is of prime importance to counteract a disease that is now recognized to start early in adult life.
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9
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Marshall L, Mathys C, Ruge D, de Berker AO, Dayan P, Stephan KE, Bestmann S. Pharmacological Fingerprints of Contextual Uncertainty. PLoS Biol 2016; 14:e1002575. [PMID: 27846219 PMCID: PMC5113004 DOI: 10.1371/journal.pbio.1002575] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 10/05/2016] [Indexed: 11/19/2022] Open
Abstract
Successful interaction with the environment requires flexible updating of our beliefs about the world. By estimating the likelihood of future events, it is possible to prepare appropriate actions in advance and execute fast, accurate motor responses. According to theoretical proposals, agents track the variability arising from changing environments by computing various forms of uncertainty. Several neuromodulators have been linked to uncertainty signalling, but comprehensive empirical characterisation of their relative contributions to perceptual belief updating, and to the selection of motor responses, is lacking. Here we assess the roles of noradrenaline, acetylcholine, and dopamine within a single, unified computational framework of uncertainty. Using pharmacological interventions in a sample of 128 healthy human volunteers and a hierarchical Bayesian learning model, we characterise the influences of noradrenergic, cholinergic, and dopaminergic receptor antagonism on individual computations of uncertainty during a probabilistic serial reaction time task. We propose that noradrenaline influences learning of uncertain events arising from unexpected changes in the environment. In contrast, acetylcholine balances attribution of uncertainty to chance fluctuations within an environmental context, defined by a stable set of probabilistic associations, or to gross environmental violations following a contextual switch. Dopamine supports the use of uncertainty representations to engender fast, adaptive responses. Pharmacological interventions and hierarchical Bayesian modelling pinpoint the roles of noradrenaline, acetylcholine, and dopamine in computing different forms of uncertainty and in sensitizing actions to our beliefs about uncertainty. Interacting with dynamic and ever-changing environments requires frequent updating of our beliefs about the world. By learning the relationships that link events in the current environmental context, it is possible to prepare and execute fast, accurate responses to those events that are predictable. However, the world’s complex dynamics give rise to uncertainty about the relationships that exist between events and uncertainty about how these relationships might change over time. Several neuromodulators have been proposed to signal these different forms of uncertainty, but their relative contributions to updating beliefs and modulating responses have remained elusive. Here we combine a probabilistic reaction time task, pharmacological interventions, and a hierarchical Bayesian learning model to identify the roles of noradrenaline, acetylcholine, and dopamine in individual computations of uncertainty. We propose that noradrenaline modulates learning about the instability of the relationships that link environmental events. Acetylcholine balances the attribution of uncertainty to unexpected events occurring within an environmental context or to gross violations of our expectations following a context change. In contrast, dopamine sensitises our actions to our beliefs about uncertainty.
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Affiliation(s)
- Louise Marshall
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom
- * E-mail:
| | - Christoph Mathys
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, United Kingdom
- Max Planck UCL Centre for Computational Psychiatry and Ageing Research, University College London, London, United Kingdom
| | - Diane Ruge
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom
- Department of Psychology and Neurosciences, Leibniz Research Centre for Working Environment and Human Factors, Technical University Dortmund, Dortmund, Germany
| | - Archy O. de Berker
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, United Kingdom
| | - Peter Dayan
- Gatsby Computational Neuroscience Unit, University College London, London, United Kingdom
| | - Klaas E. Stephan
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, United Kingdom
- Translational Neuromodeling Unit, Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zurich, Switzerland
- Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Sven Bestmann
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom
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10
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Harrison TC, Pinto L, Brock JR, Dan Y. Calcium Imaging of Basal Forebrain Activity during Innate and Learned Behaviors. Front Neural Circuits 2016; 10:36. [PMID: 27242444 PMCID: PMC4863728 DOI: 10.3389/fncir.2016.00036] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 04/18/2016] [Indexed: 11/13/2022] Open
Abstract
The basal forebrain (BF) plays crucial roles in arousal, attention, and memory, and its impairment is associated with a variety of cognitive deficits. The BF consists of cholinergic, GABAergic, and glutamatergic neurons. Electrical or optogenetic stimulation of BF cholinergic neurons enhances cortical processing and behavioral performance, but the natural activity of these cells during behavior is only beginning to be characterized. Even less is known about GABAergic and glutamatergic neurons. Here, we performed microendoscopic calcium imaging of BF neurons as mice engaged in spontaneous behaviors in their home cages (innate) or performed a go/no-go auditory discrimination task (learned). Cholinergic neurons were consistently excited during movement, including running and licking, but GABAergic and glutamatergic neurons exhibited diverse responses. All cell types were activated by overt punishment, either inside or outside of the discrimination task. These findings reveal functional similarities and distinctions between BF cell types during both spontaneous and task-related behaviors.
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Affiliation(s)
- Thomas C Harrison
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley Berkeley, CA, USA
| | - Lucas Pinto
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley Berkeley, CA, USA
| | - Julien R Brock
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley Berkeley, CA, USA
| | - Yang Dan
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley Berkeley, CA, USA
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11
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Chaves-Coira I, Barros-Zulaica N, Rodrigo-Angulo M, Núñez Á. Modulation of Specific Sensory Cortical Areas by Segregated Basal Forebrain Cholinergic Neurons Demonstrated by Neuronal Tracing and Optogenetic Stimulation in Mice. Front Neural Circuits 2016; 10:28. [PMID: 27147975 PMCID: PMC4837153 DOI: 10.3389/fncir.2016.00028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 03/29/2016] [Indexed: 12/22/2022] Open
Abstract
Neocortical cholinergic activity plays a fundamental role in sensory processing and cognitive functions. Previous results have suggested a refined anatomical and functional topographical organization of basal forebrain (BF) projections that may control cortical sensory processing in a specific manner. We have used retrograde anatomical procedures to demonstrate the existence of specific neuronal groups in the BF involved in the control of specific sensory cortices. Fluoro-Gold (FlGo) and Fast Blue (FB) fluorescent retrograde tracers were deposited into the primary somatosensory (S1) and primary auditory (A1) cortices in mice. Our results revealed that the BF is a heterogeneous area in which neurons projecting to different cortical areas are segregated into different neuronal groups. Most of the neurons located in the horizontal limb of the diagonal band of Broca (HDB) projected to the S1 cortex, indicating that this area is specialized in the sensory processing of tactile stimuli. However, the nucleus basalis magnocellularis (B) nucleus shows a similar number of cells projecting to the S1 as to the A1 cortices. In addition, we analyzed the cholinergic effects on the S1 and A1 cortical sensory responses by optogenetic stimulation of the BF neurons in urethane-anesthetized transgenic mice. We used transgenic mice expressing the light-activated cation channel, channelrhodopsin-2, tagged with a fluorescent protein (ChR2-YFP) under the control of the choline-acetyl transferase promoter (ChAT). Cortical evoked potentials were induced by whisker deflections or by auditory clicks. According to the anatomical results, optogenetic HDB stimulation induced more extensive facilitation of tactile evoked potentials in S1 than auditory evoked potentials in A1, while optogenetic stimulation of the B nucleus facilitated either tactile or auditory evoked potentials equally. Consequently, our results suggest that cholinergic projections to the cortex are organized into segregated pools of neurons that may modulate specific cortical areas.
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Affiliation(s)
- Irene Chaves-Coira
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid Madrid, Spain
| | - Natali Barros-Zulaica
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid Madrid, Spain
| | - Margarita Rodrigo-Angulo
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid Madrid, Spain
| | - Ángel Núñez
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid Madrid, Spain
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12
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Paul S, Jeon WK, Bizon JL, Han JS. Interaction of basal forebrain cholinergic neurons with the glucocorticoid system in stress regulation and cognitive impairment. Front Aging Neurosci 2015; 7:43. [PMID: 25883567 PMCID: PMC4382969 DOI: 10.3389/fnagi.2015.00043] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 03/12/2015] [Indexed: 11/28/2022] Open
Abstract
A substantial number of studies on basal forebrain (BF) cholinergic neurons (BFCN) have provided compelling evidence for their role in the etiology of stress, cognitive aging, Alzheimer’s disease (AD), and other neurodegenerative diseases. BFCN project to a broad range of cortical sites and limbic structures, including the hippocampus, and are involved in stress and cognition. In particular, the hippocampus, the primary target tissue of the glucocorticoid stress hormones, is associated with cognitive function in tandem with hypothalamic-pituitary-adrenal (HPA) axis modulation. The present review summarizes glucocorticoid and HPA axis research to date in an effort to establish the manner in which stress affects the release of acetylcholine (ACh), glucocorticoids, and their receptor in the context of cognitive processes. We attempt to provide the molecular interactive link between the glucocorticoids and cholinergic system that contributes to BFCN degeneration in stress-induced acceleration of cognitive decline in aging and AD. We also discuss the importance of animal models in facilitating such studies for pharmacological use, to which could help decipher disease states and propose leads for pharmacological intervention.
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Affiliation(s)
- Saswati Paul
- Department of Biological Sciences, Konkuk University Seoul, South Korea
| | - Won Kyung Jeon
- Herbal Medicine Research Division, Korea Institute of Oriental Medicine Daejeon, South Korea
| | - Jennifer L Bizon
- Department of Neuroscience, College of Medicine, Evelyn F. and William L. McKnight Brain Institute, University of Florida Gainesville, FL, USA
| | - Jung-Soo Han
- Department of Biological Sciences, Konkuk University Seoul, South Korea
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13
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Ameliorating Effects of Ethanol Extract of Fructus mume on Scopolamine-Induced Memory Impairment in Mice. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 2015:102734. [PMID: 25705233 PMCID: PMC4331472 DOI: 10.1155/2015/102734] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 12/29/2014] [Indexed: 11/17/2022]
Abstract
We previously reported that Fructus mume (F. mume) extract shows protective effects on memory impairments and anti-inflammatory effects induced by chronic cerebral hypoperfusion. Neurodegeneration of basal cholinergic neurons is also observed in the brain with chronic cerebral hypoperfusion. Therefore, the present study was conducted to examine whether F. mume extracts enhance cognitive function via the action of cholinergic neuron using a scopolamine-induced animal model of memory impairments. F. mume (50, 100, or 200 mg/kg) was administered to C57BL/6 mice for 14 days (days 1-14) and memory impairment was induced by scopolamine (1 mg/kg), a muscarinic receptor antagonist for 7 days (days 8-14). Spatial memory was assessed using Morris water maze and hippocampal level of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) was examined by ELISA and immunoblotting. Mice that received scopolamine alone showed impairments in acquisition and retention in Morris water maze task and increased activity of AChE in the hippocampus. Mice that received F. mume and scopolamine showed no scopolamine-induced memory impairment and increased activity of AChE. In addition, treatments of F. mume increased ChAT expression in the hippocampus. These results indicated that F. mume might enhance cognitive function via action of cholinergic neurons.
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14
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Meyer-Baron M, Knapp G, Schäper M, van Thriel C. Meta-analysis on occupational exposure to pesticides--neurobehavioral impact and dose-response relationships. ENVIRONMENTAL RESEARCH 2015; 136:234-45. [PMID: 25460642 DOI: 10.1016/j.envres.2014.09.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 09/01/2014] [Accepted: 09/16/2014] [Indexed: 05/22/2023]
Abstract
While the health impact of high exposures to pesticides is acknowledged, the impact of chronic exposures in the absence of acute poisonings is controversial. A systematic analysis of dose-response relationships is still missing. Its absence may provoke alternative explanations for altered performances. Consequently, opportunities for health prevention in the occupational and environmental field may be missed. Objectives were (1) quantification of the neurotoxic impact of pesticides by an analysis of functional alterations in workers measured by neuropsychological performance tests, (2) estimates of dose-response relationships on the basis of exposure duration, and (3) exploration of susceptible subgroups. The meta-analysis employed a random effects model to obtain overall effects for individual performance tests. Twenty-two studies with a total of 1758 exposed and 1260 reference individuals met the inclusion criteria. At least three independent outcomes were available for twenty-six performance variables. Significant performance effects were shown in adults and referred to both cognitive and motor performances. Effect sizes ranging from dRE=-0.14 to dRE=-0.67 showed consistent outcomes for memory and attention. Relationships between effect sizes and exposure duration were indicated for individual performance variables and the total of measured performances. Studies on adolescents had to be analyzed separately due to numerous outliers. The large variation among outcomes hampered the analysis of the susceptibility in this group, while data on female workers was too scant for the analysis. Relationships exist between the impact of pesticides on performances and exposure duration. A change in test paradigms would help to decipher the impact more specifically. The use of biomarkers appropriate for lower exposures would allow a better prevention of neurotoxic effects due to occupational and environmental exposure. Intervention studies in adolescents seem warranted to specify their risk.
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Affiliation(s)
- Monika Meyer-Baron
- IfADo - Leibniz Research Centre for Working Environment and Human Factors, Research Group: Neurotoxicology and Chemosensation, Ardeystr. 67, D-44139 Dortmund, Germany.
| | - Guido Knapp
- TU Dortmund University, Department of Statistics, Vogelpothsweg 87, D-44227 Dortmund, Germany
| | - Michael Schäper
- IfADo - Leibniz Research Centre for Working Environment and Human Factors, Research Group: Neurotoxicology and Chemosensation, Ardeystr. 67, D-44139 Dortmund, Germany
| | - Christoph van Thriel
- IfADo - Leibniz Research Centre for Working Environment and Human Factors, Research Group: Neurotoxicology and Chemosensation, Ardeystr. 67, D-44139 Dortmund, Germany
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15
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Abstract
Cholinergic neurotransmission has been shown to play an important role in modulating attentional processing of visual stimuli. However, it is not yet clear whether the neurochemical acetylcholine (ACh) is necessary exclusively for visual attention, or if it also contributes to attentional functions through some modality-independent (supramodal) mechanism. To answer this question, we examined the effects of reduced cortical cholinergic afferentation on both a traditional visual and a novel olfactory five-choice serial reaction time task (5-CSRTT), the benchmark rodent test of sustained attention in rats. Following the successful acquisition of both modalities of the task, the rats underwent either a cholinergic immunotoxic- or sham-lesion surgery of the nucleus basalis magnocellularis (NBM), the basal forebrain nuclei that provide the majority of neocortical ACh. Reduced cholinergic afferentation to the neocortex was induced by bilaterally infusing the cholinergic immunotoxin 192 IgG-saporin into the NBM. After surgery, ACh-NBM-lesioned rats performed comparably to sham-lesioned rats under the conditions of low attentional demand, but displayed behavioral decrements relative to the sham-lesioned rats when the attentional demands of the task were increased. Moreover, this decrement in attentional functioning correlated significantly with the number of choline acetyltransferase-immunoreactive cells in the NBM. Importantly, the nature of this behavioral decrement was identical in the visual and olfactory 5-CSRTTs. Together, these data suggest the presence of a supramodal attentional modulatory cortical network whose activity is dependent on cholinergic innervation from the NBM.
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16
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Pinto L, Goard MJ, Estandian D, Xu M, Kwan AC, Lee SH, Harrison TC, Feng G, Dan Y. Fast modulation of visual perception by basal forebrain cholinergic neurons. Nat Neurosci 2013; 16:1857-1863. [PMID: 24162654 PMCID: PMC4201942 DOI: 10.1038/nn.3552] [Citation(s) in RCA: 360] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 09/18/2013] [Indexed: 12/14/2022]
Abstract
The basal forebrain provides the primary source of cholinergic input to the cortex, and it has a crucial function in promoting wakefulness and arousal. However, whether rapid changes in basal forebrain neuron spiking in awake animals can dynamically influence sensory perception is unclear. Here we show that basal forebrain cholinergic neurons rapidly regulate cortical activity and visual perception in awake, behaving mice. Optogenetic activation of the cholinergic neurons or their V1 axon terminals improved performance of a visual discrimination task on a trial-by-trial basis. In V1, basal forebrain activation enhanced visual responses and desynchronized neuronal spiking; these changes could partly account for the behavioral improvement. Conversely, optogenetic basal forebrain inactivation decreased behavioral performance, synchronized cortical activity and impaired visual responses, indicating the importance of cholinergic activity in normal visual processing. These results underscore the causal role of basal forebrain cholinergic neurons in fast, bidirectional modulation of cortical processing and sensory perception.
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Affiliation(s)
- Lucas Pinto
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
| | - Michael J Goard
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
| | - Daniel Estandian
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
| | - Min Xu
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
| | - Alex C Kwan
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
| | - Seung-Hee Lee
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
| | - Thomas C Harrison
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
| | - Guoping Feng
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Yang Dan
- Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
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17
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Poorthuis RB, Mansvelder HD. Nicotinic acetylcholine receptors controlling attention: behavior, circuits and sensitivity to disruption by nicotine. Biochem Pharmacol 2013; 86:1089-98. [PMID: 23856288 DOI: 10.1016/j.bcp.2013.07.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/01/2013] [Accepted: 07/02/2013] [Indexed: 11/26/2022]
Abstract
Attention is a central cognitive function that enables long-term engagement in a task and suppression of irrelevant information to obtain future goals. The prefrontal cortex (PFC) is the main link in integrating emotional and motivational state of an animal to regulate top-down attentional processes. Acetylcholine modulates PFC neuronal networks by activating nicotinic acetylcholine receptors (nAChRs) to support attention. However, how neuronal activity changes in the PFC during attention and which nAChR subtypes mediate this is only rudimentarily understood, but progress is being made. Recently, exciting new insights were obtained in the dynamics of cholinergic signaling in the PFC and modes of acetylcholine transmission via nAChRs in the cortex. In addition, mechanisms are uncovered on how the PFC circuitry is regulated by nAChRs. Novel studies show that endogenous activation of nAChRs in the PFC plays a central role in controlling attention. Here, we review current insights into how different subtypes of nAChRs expressed by distinct types of neurons in the PFC circuitry shape attention. In addition we discuss the impact of nicotine on the cholinergic system and prefrontal cortical circuits. Low concentrations of nicotine, as experienced by smokers, interfere with cholinergic signaling. In the long-term exposure to nicotine during adolescence leads to maladaptive adaptations of the PFC circuitry, which ultimately leads to a decrement in attention performance, again emphasizing the importance of nAChRs in attention.
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Affiliation(s)
- Rogier B Poorthuis
- Department of Integrative Neurophysiology, CNCR, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
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18
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Broussard JI. Posterior parietal cortex dynamically ranks topographic signals via cholinergic influence. Front Integr Neurosci 2012; 6:32. [PMID: 22712008 PMCID: PMC3375019 DOI: 10.3389/fnint.2012.00032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 05/28/2012] [Indexed: 01/08/2023] Open
Abstract
The hypothesis to be discussed in this review is that posterior parietal cortex (PPC) is directly involved in selecting relevant stimuli and filtering irrelevant distractors. The PPC receives input from several sensory modalities and integrates them in part to direct the allocation of resources to optimize gains. In conjunction with prefrontal cortex, nucleus accumbens, and basal forebrain cholinergic nuclei, it comprises a network mediating sustained attentional performance. Numerous anatomical, neurophysiological, and lesion studies have substantiated the notion that the basic functions of the PPC are conserved from rodents to humans. One such function is the detection and selection of relevant stimuli necessary for making optimal choices or responses. The issues to be addressed here are how behaviorally relevant targets recruit oscillatory potentials and spiking activity of posterior parietal neurons compared to similar yet irrelevant stimuli. Further, the influence of cortical cholinergic input to PPC in learning and decision-making is also discussed. I propose that these neurophysiological correlates of attention are transmitted to frontal cortical areas contributing to the top-down selection of stimuli in a timely manner.
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Affiliation(s)
- John I Broussard
- Department of Neuroscience, Center on Addiction, Learning, Memory, Baylor College of Medicine, Houston TX, USA
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19
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Romberg C, Bussey TJ, Saksida LM. Paying more attention to attention: towards more comprehensive cognitive translation using mouse models of Alzheimer's disease. Brain Res Bull 2012; 92:49-55. [PMID: 22390982 DOI: 10.1016/j.brainresbull.2012.02.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/14/2011] [Accepted: 02/15/2012] [Indexed: 11/27/2022]
Abstract
The cognitive phenotyping of mouse models of Alzheimer's disease (AD) currently focuses on impairments in learning and memory. However, AD is not simply a memory disorder, but other cognitive domains, and in particular attention, can also be impaired even at very early stages of the disease. In this review we argue for the benefits of including other constructs, and in particular attention, in preclinical studies to identify drug targets and disease mechanisms of AD in mouse models. First we give a brief account of the evidence for attentional deficits in AD; we then summarise methods to assess equivalent aspects of attention in mice, followed by a review of recent evidence for attentional impairments in widely used mouse models of AD. We conclude by suggesting that a multidimensional approach to cognitive assessment in preclinical models, in which a number of aspects of cognition are investigated while confounding factors are minimized, is becoming increasingly feasible and may contribute significantly towards the development of more targeted therapeutic interventions.
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Affiliation(s)
- Carola Romberg
- Max-Planck-Institute for Psychiatry, 80997 Munich, Germany.
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20
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Abstract
As indicated by the profound cognitive impairments caused by cholinergic receptor antagonists, cholinergic neurotransmission has a vital role in cognitive function, specifically attention and memory encoding. Abnormally regulated cholinergic neurotransmission has been hypothesized to contribute to the cognitive symptoms of neuropsychiatric disorders. Loss of cholinergic neurons enhances the severity of the symptoms of dementia. Cholinergic receptor agonists and acetylcholinesterase inhibitors have been investigated for the treatment of cognitive dysfunction. Evidence from experiments using new techniques for measuring rapid changes in cholinergic neurotransmission provides a novel perspective on the cholinergic regulation of cognitive processes. This evidence indicates that changes in cholinergic modulation on a timescale of seconds is triggered by sensory input cues and serves to facilitate cue detection and attentional performance. Furthermore, the evidence indicates cholinergic induction of evoked intrinsic, persistent spiking mechanisms for active maintenance of sensory input, and planned responses. Models have been developed to describe the neuronal mechanisms underlying the transient modulation of cortical target circuits by cholinergic activity. These models postulate specific locations and roles of nicotinic and muscarinic acetylcholine receptors and that cholinergic neurotransmission is controlled in part by (cortical) target circuits. The available evidence and these models point to new principles governing the development of the next generation of cholinergic treatments for cognitive disorders.
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21
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Quinn LK, Nitz DA, Chiba AA. Learning-dependent dynamics of beta-frequency oscillations in the basal forebrain of rats. Eur J Neurosci 2010; 32:1507-15. [PMID: 21039960 DOI: 10.1111/j.1460-9568.2010.07422.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cholinergic, GABAergic and glutamatergic projection neurons of the basal forebrain (BF) innervate widespread regions of the neocortex and are thought to modulate learning and attentional processes. Although it is known that neuronal cell types in the BF exhibit oscillatory firing patterns, whether the BF as a whole shows oscillatory field potential activity, and whether such neuronal patterns relate to components of cognitive tasks, has yet to be determined. To this end, local field potentials (LFPs) were recorded from the BF of rats performing an associative learning task wherein neutral objects were paired with differently valued reinforcers (pellets). Over time, rats developed preferences for the different objects based on pellet-value, indicating that the pairings had been well learned. LFPs from all rats revealed robust, short-lived bursts of beta-frequency oscillations (∼25 Hz) around the time of object encounter. Beta-frequency LFP events were found to be learning-dependent, with beta-frequency peak amplitudes significantly greater on the first day of the task when object-reinforcement pairings were novel than on the last day when pairings were well learned. The findings indicate that oscillatory bursting field potential activity occurs in the BF in freely behaving animals. Furthermore, the temporal distribution of these bursts suggests that they are probably relevant to associative learning.
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Affiliation(s)
- Laleh K Quinn
- Department of Cognitive Science, University of California at San Diego.
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22
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Köhler C, Bista P, Götz J, Schröder H. Analysis of the cholinergic pathology in the P301L tau transgenic pR5 model of tauopathy. Brain Res 2010; 1347:111-24. [DOI: 10.1016/j.brainres.2010.05.076] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 05/21/2010] [Accepted: 05/24/2010] [Indexed: 01/28/2023]
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23
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Klinkenberg I, Blokland A. The validity of scopolamine as a pharmacological model for cognitive impairment: A review of animal behavioral studies. Neurosci Biobehav Rev 2010; 34:1307-50. [DOI: 10.1016/j.neubiorev.2010.04.001] [Citation(s) in RCA: 413] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 04/01/2010] [Accepted: 04/08/2010] [Indexed: 01/06/2023]
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24
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Anselme P. The uncertainty processing theory of motivation. Behav Brain Res 2009; 208:291-310. [PMID: 20035799 DOI: 10.1016/j.bbr.2009.12.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 12/13/2009] [Accepted: 12/16/2009] [Indexed: 10/20/2022]
Abstract
Most theories describe motivation using basic terminology (drive, 'wanting', goal, pleasure, etc.) that fails to inform well about the psychological mechanisms controlling its expression. This leads to a conception of motivation as a mere psychological state 'emerging' from neurophysiological substrates. However, the involvement of motivation in a large number of behavioural parameters (triggering, intensity, duration, and directedness) and cognitive abilities (learning, memory, decision, etc.) suggest that it should be viewed as an information processing system. The uncertainty processing theory (UPT) presented here suggests that motivation is the set of cognitive processes allowing organisms to extract information from the environment by reducing uncertainty about the occurrence of psychologically significant events. This processing of information is shown to naturally result in the highlighting of specific stimuli. The UPT attempts to solve three major problems: (i) how motivations can affect behaviour and cognition so widely, (ii) how motivational specificity for objects and events can result from nonspecific neuropharmacological causal factors (such as mesolimbic dopamine), and (iii) how motivational interactions can be conceived in psychological terms, irrespective of their biological correlates. The UPT is in keeping with the conceptual tradition of the incentive salience hypothesis while trying to overcome the shortcomings inherent to this view.
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Affiliation(s)
- Patrick Anselme
- Centre de Neurosciences Cognitives et Comportementales, Université de Liège, Liège, Belgium.
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25
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Redrobe JP, Nielsen EØ, Christensen JK, Peters D, Timmermann DB, Olsen GM. α7 nicotinic acetylcholine receptor activation ameliorates scopolamine-induced behavioural changes in a modified continuous Y-maze task in mice. Eur J Pharmacol 2009; 602:58-65. [DOI: 10.1016/j.ejphar.2008.09.035] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Revised: 09/12/2008] [Accepted: 09/17/2008] [Indexed: 11/28/2022]
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26
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Fragkouli A, Pachnis V, Stylianopoulou F. Sex differences in water maze performance and cortical neurotrophin levels of LHX7 null mutant mice. Neuroscience 2008; 158:1224-33. [PMID: 19095044 DOI: 10.1016/j.neuroscience.2008.11.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 10/20/2008] [Accepted: 11/13/2008] [Indexed: 01/08/2023]
Abstract
Mice lacking both alleles of the LIM-homeobox gene Lhx7 display dramatically reduced number of forebrain cholinergic neurons. Given the fact that sex differences are consistently observed in forebrain cholinergic function, in the present study we investigated whether the absence of LHX7 differentially affects water maze performance in the two sexes. Herein we demonstrate that LHX7 null mutants display a sex-dependent impairment in water maze, with females appearing more affected than males. Moreover, neurotrophin assessment revealed a compensatory increase of brain-derived neurotrophic factor and neurotrophin 3 in the neocortex of both male and female mutants and an increase of nerve growth factor levels only in the females. Nevertheless, the compensatory increase of cortical neurotrophin levels did not restore cognitive abilities of Lhx7 homozygous mutants. Finally, our analysis revealed that cortical neurotrophin levels correlate negatively with water maze proficiency, indicating that there is an optimal neurotrophin level for successful cognitive performance.
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Affiliation(s)
- A Fragkouli
- Department of Basic Sciences, University of Athens, 11527 Athens, Greece
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27
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Delano PH, Elgueda D, Hamame CM, Robles L. Selective attention to visual stimuli reduces cochlear sensitivity in chinchillas. J Neurosci 2007; 27:4146-53. [PMID: 17428992 PMCID: PMC6672531 DOI: 10.1523/jneurosci.3702-06.2007] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
It is generally accepted that during periods of attention to specific stimuli there are changes in the neural activity of central auditory structures; however, it is controversial whether attention can modulate auditory responses at the cochlear level. Several studies performed in animals as well as in humans have attempted to find a modulation of cochlear responses during visual attention with contradictory results. Here, we have appraised cochlear sensitivity in behaving chinchillas by measuring, with a chronically implanted round-window electrode, sound-evoked auditory-nerve compound action potentials and cochlear microphonics, a measure of outer hair cell function, during selective attention to visual stimuli. Chinchillas were trained in a visual discrimination or in an auditory frequency discrimination two-choice task. We found a significant decrease of cochlear sensitivity during the period of attention to visual stimuli in the animals performing the visual discrimination task, but not in those performing the auditory task, demonstrating that this physiological effect is related to selective attention to visual stimuli rather than to an increment in arousal level. Furthermore, the magnitude of the cochlear-sensitivity reductions increased in sessions performed with shorter target-light durations (4-0.5 s), suggesting that this effect is stronger for higher attentional demands of the task. These results demonstrate that afferent auditory activity is modulated by selective attention as early as at sensory transduction, possibly through activation of olivocochlear efferent fibers.
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Affiliation(s)
- Paul H. Delano
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
| | - Diego Elgueda
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
| | - Carlos M. Hamame
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
| | - Luis Robles
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
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28
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Maddux JM, Kerfoot EC, Chatterjee S, Holland PC. Dissociation of attention in learning and action: effects of lesions of the amygdala central nucleus, medial prefrontal cortex, and posterior parietal cortex. Behav Neurosci 2007; 121:63-79. [PMID: 17324051 PMCID: PMC2853715 DOI: 10.1037/0735-7044.121.1.63] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Many associative learning theories assert that the predictive accuracy of events affects the allocation of attention to them. More reliable predictors of future events are usually more likely to control action based on past learning, but less reliable predictors are often more likely to capture attention when new information is acquired. Previous studies showed that a circuit including the amygdala central nucleus (CEA) and the cholinergic substantia innominata/nucleus basalis magnocellularis (SI/nBM) is important for both sustained attention guiding action in a five-choice serial reaction time (5CSRT) task and for enhanced new learning about less predictive cues in a serial conditioning task. In this study, the authors found that lesions of the cholinergic afferents of the medial prefrontal cortex interfered with 5CSRT performance but not with surprise-induced enhancement of learning, whereas lesions of cholinergic afferents of posterior parietal cortex impaired the latter effects but did not affect 5CSRT performance. CEA lesions impaired performance in both tasks. These results are consistent with the view that CEA affects these distinct aspects of attention by influencing the activity of separate, specialized cortical regions via modulation of SI/nBM.
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Affiliation(s)
- Jean-Marie Maddux
- Department of Psychological and Brain Sciences, John Hopkins University, Baltimore, MD 21218, USA
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Holland PC. Disconnection of the amygdala central nucleus and the substantia innominata/nucleus basalis magnocellularis disrupts performance in a sustained attention task. Behav Neurosci 2007; 121:80-9. [PMID: 17324052 PMCID: PMC2241658 DOI: 10.1037/0735-7044.121.1.80] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The basal forebrain cholinergic system is broadly implicated in the regulation of attention. Disruptions in the function of this system produce impairments in many attentional functions, including the performance of well-learned responses under increased attentional load and the surprise-induced enhancement of learning rate. Similarly, lesions of the amygdala central nucleus (CeA) have been found to impair attentional function in some circumstances. In the present article, the effects of lesions that disconnected CeA from the cholinergic substantia innominata/nucleus basalis magnocellularis (SI/nBM) on performance are examined in a modified 5-choice serial reaction time (5CSRT) task, thought to assess selective or sustained attention. The lesions impaired performance under conditions of increased attentional load, suggesting that a circuit that includes CeA and SI/nBM regulates these aspects of attention.
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Affiliation(s)
- Peter C Holland
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA.
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Thouvarecq R, Caston J, Protais P. Cholinergic system, rearing environment and trajectory learning during aging in mice. Physiol Behav 2007; 90:155-64. [PMID: 17074375 DOI: 10.1016/j.physbeh.2006.09.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Revised: 09/17/2006] [Accepted: 09/20/2006] [Indexed: 10/24/2022]
Abstract
Three, 12- and 20-month-old C57BL6/J mice, reared in standard conditions or in enriched environments, were administered subcutaneously either scopolamine hydrobromide, 0.6 or 1.2 mg kg(-1), or physiological saline (control mice) 15 min before testing their abilities to find an invisible platform in a modified version of the Morris water maze, the starting point being kept unchanged throughout the experiment to allow the aged animals to solve the task. The results demonstrated that: 1) All control mice, whatever their age, were able to learn the platform location, but the number of trials needed to reach the learning criterion (3 consecutive trials in less than 8 s) increased with age; 2) All the scopolamine-treated mice, whatever their age, were also able to learn the platform location. However, compared to age-matched controls, the number of trials needed to reach the learning criterion was greater; 3) Rearing the animals in an enriched environment antagonized the effect of scopolamine, but only in the youngest (3 month-old) mice. All control and scopolamine-treated mice, whatever their age and their rearing environment, remembered, 7 days later, the platform location.
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Affiliation(s)
- R Thouvarecq
- UPRES PSY.CO EA 1780, Faculté des Sciences, Laboratoire de Neurobiologie de l'Apprentissage, Université de Rouen, 76821 Mont-Saint-Aignan Cedex, France
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31
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McQuail JA, Burk JA. Evaluation of muscarinic and nicotinic receptor antagonists on attention and working memory. Pharmacol Biochem Behav 2006; 85:796-803. [PMID: 17196638 DOI: 10.1016/j.pbb.2006.11.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Revised: 11/09/2006] [Accepted: 11/21/2006] [Indexed: 02/05/2023]
Abstract
Cholinergic receptor antagonists are commonly used to model attentional and mnemonic impairments associated with neuropsychiatric disorders such as Alzheimer's disease. However, few studies have systematically assessed the effects of these drugs following manipulations that affect attention or working memory within the same task. In the present experiment, rats were trained to discriminate visual signals from "blank" trials when no signal was presented. This task was modified to include retention intervals on some trials to tax working memory. During standard task performance, rats received systemic injections of the muscarinic receptor antagonist, scopolamine, or of the nicotinic receptor antagonist, mecamylamine. A second experiment tested the effects on this task of co-administering doses of scopolamine and mecamylamine that, when administered alone, did not significantly affect task performance. Scopolamine (0.3 and 1.0 mg/kg) decreased detection of 500 ms signals but did not affect accurate identification of non-signals. Scopolamine did not differentially affect performance across the retention interval. Elevated omission rates were associated with high doses of scopolamine or mecamylamine. Combination drug treatment was associated with decreased signal detection and elevated omission rates. Collectively, the data suggest that muscarinic and nicotinic receptor antagonists do not exclusively impair working memory.
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Affiliation(s)
- Joseph A McQuail
- Department of Psychology, College of William and Mary, P.O. Box 8795, Williamsburg, VA 23187, USA
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32
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Browne RO, Moyal-Segal LB, Zumsteg D, David Y, Kofman O, Berger A, Soreq H, Friedman A. Coding region paraoxonase polymorphisms dictate accentuated neuronal reactions in chronic, sub-threshold pesticide exposure. FASEB J 2006; 20:1733-5. [PMID: 16807370 DOI: 10.1096/fj.05-5576fje] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Organophosphate pesticides (OPs), known inhibitors of acetylcholinesterase (AChE), are used extensively throughout the world. Recent studies have focused on the ACHE/PON1 locus as a determinant of inherited susceptibility to environmental OP exposure. To explore the relationship of the corresponding gene-environment interactions with brain activity, we integrated neurophysiologic, neuropsychological, biochemical, and genetic methods. Importantly, we found that subthreshold OP exposure leads to discernible physiological consequences that are significantly influenced by inherited factors. Cortical EEG analyses by LORETA revealed significantly decreased theta activity in the hippocampus, parahippocampal regions, and the cingulate cortex, as well as increased beta activity in the prefrontal cortex of exposed individuals-areas known to play a role in cholinergic-associated cognitive functions. Through neuropsychological testing, we identified an appreciable deficit in the visual recall in exposed individuals. Other neuropsychological tests revealed no significant differences between exposed and non-exposed individuals, attesting to the specificity of our findings. Biochemical analyses of blood samples revealed increases in paraoxonase and arylesterase activities and reduced serum acetylcholinesterase activity in chronically exposed individuals. Notably, specific paraoxonase genotypes were found to be associated with these exposure-related changes in blood enzyme activities and abnormal EEG patterns. Thus, gene-environment interactions involving the ACHE/PON1 locus may be causally involved in determining the physiological response to OP exposure.
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Affiliation(s)
- R Orie Browne
- Department of Physiology, Soroka University Medical Center, The Hebrew University of Jerusalem, Jerusalem, Israel
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33
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Giessing C, Thiel CM, Rösler F, Fink GR. The modulatory effects of nicotine on parietal cortex activity in a cued target detection task depend on cue reliability. Neuroscience 2006; 137:853-64. [PMID: 16309846 DOI: 10.1016/j.neuroscience.2005.10.005] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Revised: 08/25/2005] [Accepted: 10/05/2005] [Indexed: 11/23/2022]
Abstract
This functional magnetic resonance imaging study investigates the effects of nicotine in a cued target detection task when changing cue reliability. Fifteen non-smoking volunteers were studied under placebo and nicotine (Nicorette polacrilex gum 1 and 2 mg). Validly and invalidly cued trials were arranged in blocks with high, middle and low cue reliability. Two effects of nicotine were investigated: its influence on i) parietal cortex activity underlying the processing of invalid vs. valid trials (i.e. validity effect) and ii) neural activity in the context of low, middle and high informative value of the cue (i.e. cue reliability effect). Nicotine did not affect behavioral performance. However, nicotine reduced the difference in the blood oxygenation level dependent (BOLD) signal between invalid and valid trials in the right intraparietal sulcus. The reduction of parietal activity in invalid trials was smaller in the low cue reliability condition. The same posterior parietal region exhibited a nicotinic modulation of BOLD activity in valid trials which was dependent on cue reliability: Nicotine specifically enhanced the neural activity during valid trials in the context of low cue reliability, i.e. when subjects are already in a state of low certainty. We speculate that the right intraparietal sulcus might be part of two networks working in parallel: one responsible for reorienting attention and the other for the cholinergic modulation of cue reliability. By reducing the use of the cue, nicotine modulates parietal activity related to reorienting attention in conditions with higher cue certainty. On the other hand, nicotine increases parietal activity in states of low certainty. This enhanced activation might influence brain regions, such as the posterior cingulate, directly involved in the processing of cue reliability.
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Affiliation(s)
- C Giessing
- Institute of Medicine, Research Centre Jülich, 52425 Jülich, Germany.
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34
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Yu AJ, Dayan P. Uncertainty, neuromodulation, and attention. Neuron 2005; 46:681-92. [PMID: 15944135 DOI: 10.1016/j.neuron.2005.04.026] [Citation(s) in RCA: 998] [Impact Index Per Article: 52.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Revised: 03/16/2005] [Accepted: 04/21/2005] [Indexed: 10/25/2022]
Abstract
Uncertainty in various forms plagues our interactions with the environment. In a Bayesian statistical framework, optimal inference and prediction, based on unreliable observations in changing contexts, require the representation and manipulation of different forms of uncertainty. We propose that the neuromodulators acetylcholine and norepinephrine play a major role in the brain's implementation of these uncertainty computations. Acetylcholine signals expected uncertainty, coming from known unreliability of predictive cues within a context. Norepinephrine signals unexpected uncertainty, as when unsignaled context switches produce strongly unexpected observations. These uncertainty signals interact to enable optimal inference and learning in noisy and changeable environments. This formulation is consistent with a wealth of physiological, pharmacological, and behavioral data implicating acetylcholine and norepinephrine in specific aspects of a range of cognitive processes. Moreover, the model suggests a class of attentional cueing tasks that involve both neuromodulators and shows how their interactions may be part-antagonistic, part-synergistic.
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Affiliation(s)
- Angela J Yu
- Gatsby Computational Neuroscience Unit, London, United Kingdom.
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35
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Conner JM, Chiba AA, Tuszynski MH. The basal forebrain cholinergic system is essential for cortical plasticity and functional recovery following brain injury. Neuron 2005; 46:173-9. [PMID: 15848797 DOI: 10.1016/j.neuron.2005.03.003] [Citation(s) in RCA: 180] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2004] [Revised: 01/27/2005] [Accepted: 03/01/2005] [Indexed: 11/26/2022]
Abstract
A reorganization of cortical representations is postulated as the basis for functional recovery following many types of nervous system injury. Neuronal mechanisms underlying this form of cortical plasticity are poorly understood. The present study investigated the hypothesis that the basal forebrain cholinergic system plays an essential role in enabling the cortical reorganization required for functional recovery following brain injury. The results demonstrate that functional recovery following cortical injury requires basal forebrain cholinergic mechanisms and suggest that the basis for this recovery is the cholinergic-dependent reorganization of motor representations. These findings raise the intriguing possibility that deficits in cholinergic function may limit functional outcomes following nervous system injury.
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Affiliation(s)
- James M Conner
- Department of Neurosciences, Unviersity of California, La Jolla, California 92093, USA.
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Sarter M, Hasselmo ME, Bruno JP, Givens B. Unraveling the attentional functions of cortical cholinergic inputs: interactions between signal-driven and cognitive modulation of signal detection. ACTA ACUST UNITED AC 2005; 48:98-111. [PMID: 15708630 DOI: 10.1016/j.brainresrev.2004.08.006] [Citation(s) in RCA: 486] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2004] [Indexed: 12/17/2022]
Abstract
Neurophysiological studies demonstrated that increases in cholinergic transmission in sensory areas enhance the cortical processing of thalamic inputs. Cholinergic activity also suppresses the retrieval of internal associations, thereby further promoting sensory input processing. Behavioral studies documented the role of cortical cholinergic inputs in attentional functions and capacities by demonstrating, for example, that the integrity of the cortical cholinergic input system is necessary for attentional performance, and that the activity of cortical cholinergic inputs is selectively enhanced during attentional performance. This review aims at integrating the neurophysiological and behavioral evidence on the functions of cortical cholinergic inputs and hypothesizes that the cortical cholinergic input system generally acts to optimize the processing of signals in attention-demanding contexts. Such signals 'recruit', via activation of basal forebrain corticopetal cholinergic projections, the cortical attention systems and thereby amplify the processing of attention-demanding signals (termed 'signal-driven cholinergic modulation of detection'). The activity of corticopetal cholinergic projections is also modulated by direct prefrontal projections to the basal forebrain and, indirectly, to cholinergic terminals elsewhere in the cortex; thus, cortical cholinergic inputs are also involved in the mediation of top-down effects, such as the knowledge-based augmentation of detection (see Footnote 1) of signals and the filtering of irrelevant information (termed 'cognitive cholinergic modulation of detection'). Thus, depending on the quality of signals and task characteristics, cortical cholinergic activity reflects the combined effects of signal-driven and cognitive modulation of detection. This hypothesis begins to explain signal intensity or duration-dependent performance in attention tasks, the distinct effects of cortex-wide versus prefrontal cholinergic deafferentation on attention performance, and it generates specific predictions concerning cortical acetylcholine (ACh) release in attention task-performing animals. Finally, the consequences of abnormalities in the regulation of cortical cholinergic inputs for the manifestation of the symptoms of major neuropsychiatric disorders are conceptualized in terms of dysregulation in the signal-driven and cognitive cholinergic modulation of detection processes.
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Affiliation(s)
- Martin Sarter
- Department of Psychology, University of Michigan, 525 E. University Ave., Ann Arbor, MI 48109-1109, USA.
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37
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Bentley P, Husain M, Dolan RJ. Effects of cholinergic enhancement on visual stimulation, spatial attention, and spatial working memory. Neuron 2004; 41:969-82. [PMID: 15046728 DOI: 10.1016/s0896-6273(04)00145-x] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2003] [Revised: 01/09/2004] [Accepted: 02/16/2004] [Indexed: 02/03/2023]
Abstract
We compared behavioral and neural effects of cholinergic enhancement between spatial attention, spatial working memory (WM), and visual control tasks, using fMRI and the anticholinesterase physostigmine. Physostigmine speeded responses nonselectively but increased accuracy selectively for attention. Physostigmine also decreased activations to visual stimulation across all tasks within primary visual cortex, increased extrastriate occipital cortex activation selectively during maintained attention and WM encoding, and decreased parietal activation selectively during maintained attention. Finally, lateralization of occipital activation as a function of the visual hemifield toward which attention or memory was directed was decreased under physostigmine. In the case of attention, this effect correlated strongly with a decrease in a behavioral measure of selective spatial processing. Our results suggest that, while cholinergic enhancement facilitates visual attention by increasing activity in extrastriate cortex generally, it accomplishes this in a manner that reduces expectation-driven selective biasing of extrastriate cortex.
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Affiliation(s)
- P Bentley
- Wellcome Department of Imaging Neuroscience, 12 Queen Square, London WC1N 3BG, UK.
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Sarter M, Bruno JP, Givens B. Attentional functions of cortical cholinergic inputs: what does it mean for learning and memory? Neurobiol Learn Mem 2004; 80:245-56. [PMID: 14521867 DOI: 10.1016/s1074-7427(03)00070-4] [Citation(s) in RCA: 220] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The hypothesis that cortical cholinergic inputs mediate attentional functions and capacities has been extensively substantiated by experiments assessing the attentional effects of specific cholinotoxic lesions of cortical cholinergic inputs, attentional performance-associated cortical acetylcholine release, and the effects of pharmacological manipulations of the excitability of basal forebrain corticopetal cholinergic projections on attentional performance. At the same time, numerous animal experiments have suggested that the integrity of cortical cholinergic inputs is not necessary for learning and memory, and a dissociation between the role of the cortical cholinergic input system in attentional functions and in learning and memory has been proposed. We speculate that this dissociation is due, at least in part, to the use of standard animal behavioral tests for the assessment of learning and memory which do not sufficiently tax defined attentional functions. Attentional processes and the allocation of attentional capacities would be expected to influence the efficacy of the acquisition and recall of declarative information and therefore, persistent abnormalities in the regulation of the cortical cholinergic input system may yield escalating impairments in learning and memory. Furthermore, the cognitive effects of loss of cortical cholinergic inputs are augmented by the disruption of the top-down regulation of attentional functions that normally acts to optimize information processing in posterior cortical areas. Because cortical cholinergic inputs play an integral role in the mediation of attentional processing, the activity of cortical cholinergic inputs is hypothesized to also determine the efficacy of learning and memory.
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Affiliation(s)
- Martin Sarter
- Departments of Psychology and Neuroscience, The Ohio State University, Columbus, OH 43210, USA.
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39
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Abstract
The integrity of the cortical cholinergic input system is necessary for attention performance. This experiment tested hypotheses concerning the lateralized contributions of cortical cholinergic inputs to attention performance by assessing the effects of unilateral lesions of basal forebrain cholinergic neurons on sustained attention performance. Loss of right-hemispheric cortical cholinergic inputs impaired the rats' ability to detect signals but did not affect nonsignal trial performance. Conversely, loss of left-hemispheric cortical cholinergic inputs increased the number of false alarms in nonsignal trials. These data correspond with hypotheses about the mediation of detection processes primarily by right-hemispheric circuits and executive aspects of attention performance by left-hemispheric systems. Cortical cholinergic inputs represent a major component of the brain's lateralized attention systems.
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40
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Chudasama Y, Dalley JW, Nathwani F, Bouger P, Robbins TW, Nathwani F. Cholinergic modulation of visual attention and working memory: dissociable effects of basal forebrain 192-IgG-saporin lesions and intraprefrontal infusions of scopolamine. Learn Mem 2004; 11:78-86. [PMID: 14747520 PMCID: PMC321317 DOI: 10.1101/lm.70904] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2003] [Accepted: 12/05/2003] [Indexed: 02/04/2023]
Abstract
Two experiments examined the effects of reductions in cortical cholinergic function on performance of a novel task that allowed for the simultaneous assessment of attention to a visual stimulus and memory for that stimulus over a variable delay within the same test session. In the first experiment, infusions of the muscarinic receptor antagonist scopolamine into the medial prefrontal cortex (mPFC) produced many omissions but did not impair rats' ability to correctly detect a brief visual stimulus. However, these animals were highly impaired in remembering the location of that stimulus following a delay period, although in a delay-independent manner. In the second experiment, another group of animals with selective 192 IgG-saporin lesions of the nucleus basalis magnocellularis (nBM) were not impaired under conditions of low-attentional demand. However, when the stimulus duration was reduced, a significant memory impairment was observed, but similar to the results of the first experiment, the nBM-lesioned animals were not impaired in attentional accuracy, although aspects of attention were compromised (e.g., omissions). These findings demonstrate that (1) cortical cholinergic depletion produces dissociable deficits in attention and memory, depending on the task demands, (2) delay-independent mnemonic deficits produced by scopolamine are probably due to impairments other than simple inattention, and (3) working memory deficits are not simply dependent on attentional difficulties per se. Together, these findings implicate the nBM cortical cholinergic system in both attentional and mnemonic processing.
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Affiliation(s)
- Yogita Chudasama
- Cambridge University, Department of Experimental Psychology, Cambridge CB2 3EB, UK.
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41
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Berger-Sweeney J. The cholinergic basal forebrain system during development and its influence on cognitive processes: important questions and potential answers. Neurosci Biobehav Rev 2003; 27:401-11. [PMID: 12946692 DOI: 10.1016/s0149-7634(03)00070-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This review seeks to address, though perhaps not answer fully, four important questions about the cholinergic basal forebrain (BF) system in developing mammals. First, what role does the cholinergic basal forebrain system play in the development of cognitive functions? Second, does the cholinergic BF system play a fundamentally similar role in development vs. adulthood? Third, does sexual dimorphism of the developing cholinergic BF system influence cognition differently in the two sexes? Finally, what role does the developing cholinergic BF system play in developmental disorders such as Down syndrome and Rett syndrome? Examples from the literature, primarily studies in mice and rats, are given in an attempt to answer these important questions.
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Affiliation(s)
- Joanne Berger-Sweeney
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA 02481, USA.
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42
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Meck WH, Williams CL. Metabolic imprinting of choline by its availability during gestation: implications for memory and attentional processing across the lifespan. Neurosci Biobehav Rev 2003; 27:385-99. [PMID: 12946691 DOI: 10.1016/s0149-7634(03)00069-1] [Citation(s) in RCA: 219] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A growing body of research supports the view that choline is an essential nutrient during early development that has long-lasting effects on memory and attentional processes throughout the lifespan. This review describes the known effects of alterations in dietary choline availability both in adulthood and during early development. Although modest effects of choline on cognitive processes have been reported when choline is administered to adult animals, we have found that the perinatal period is a critical time for cholinergic organization of brain function. Choline supplementation during this period increases memory capacity and precision of the young adult and appears to prevent age-related memory and attentional decline. Deprivation of choline during early development leads to compromised cognitive function and increased decline with age. We propose that this organizational effect of choline availability may be due to relatively permanent alterations in the functioning of the cholinergic synapse, which we have called 'metabolic imprinting'.
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Affiliation(s)
- Warren H Meck
- Department of Psychological and Brain Sciences, Duke University, 9 Flowers Drive, Box 90086, Durham, NC 27708-0086, USA.
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43
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Differential pattern of cAMP response element-binding protein activation in the rat brain after conditioned aversion as a function of the associative process engaged: taste versus context association. J Neurosci 2003. [PMID: 12853429 DOI: 10.1523/jneurosci.23-14-06102.2003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ample data indicate that cAMP-response element-binding protein (CREB) is essential for the formation of long-term memory in various species and learning systems. This implies that activated CREB could delineate neuronal circuits that subserve items in memory, while leaving open the possibility that the specifics of CREB activation itself contribute to the specificity of the internal representation encoded by the relevant circuit. We describe here the differential activation of CREB in the rat brain as a function of two related yet distinct forms of aversive conditioning: conditioned taste aversion (CTA) and conditioned context aversion (CCA). We found that CTA induces strong CREB activation in the insular cortex (IC) and the lateral septum (LS), but not in the parietal cortex (PC) and the medial septum (MS). In contrast, CCA results in strong activation in the PC and MS, but not in the IC and LS. These findings are congruent with a model that links differential pattern of activity within the LS and the MS with the acquisition of elemental versus contextual conditioning and, more generally, with the notion that CREB activation delineates learning-dependent circuits as a function of the type of cognitive process engaged.
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Conner JM, Culberson A, Packowski C, Chiba AA, Tuszynski MH. Lesions of the Basal forebrain cholinergic system impair task acquisition and abolish cortical plasticity associated with motor skill learning. Neuron 2003; 38:819-29. [PMID: 12797965 DOI: 10.1016/s0896-6273(03)00288-5] [Citation(s) in RCA: 278] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The contribution of the basal forebrain cholinergic system in mediating plasticity of cortical sensorimotor representations was examined in the context of normal learning. The effects of specific basal forebrain cholinergic lesions upon cortical reorganization associated with learning a skilled motor task were investigated, addressing, for the first time, the functional consequences of blocking cortical map plasticity. Results demonstrate that disrupting basal forebrain cholinergic function disrupts cortical map reorganization and impairs motor learning. Cholinergic lesions do not impair associative fear learning or overall sensorimotor function. These results support the hypothesis that the basal forebrain cholinergic system may be specifically implicated in forms of learning requiring plasticity of cortical representations.
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Affiliation(s)
- James M Conner
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA.
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45
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Gastard M, Jensen SL, Martin JR, Williams EA, Zahm DS. The caudal sublenticular region/anterior amygdaloid area is the only part of the rat forebrain and mesopontine tegmentum occupied by magnocellular cholinergic neurons that receives outputs from the central division of extended amygdala. Brain Res 2002; 957:207-22. [PMID: 12445963 DOI: 10.1016/s0006-8993(02)03513-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Ascending cholinergic projections and the central nucleus of the amygdala (CeA) have both been implicated in attentional and orienting mechanisms leading to adaptive behavioral responses. In view of this, the present study was carried out to identify relevant neuroanatomical relationships in the form of projections from the CeA and a related structure, the dorsolateral divison of the bed nucleus of the stria terminalis (dlBST), to parts of the basal forebrain and mesopontine tegmentum that contain magnocellular cholinergic neurons. The CeA and dlBST are components of the 'central division of extended amygdala'. Following injections of the anterogradely transported compounds, Phaseolus vulgaris-leucoagglutinin or biotinylated dextran amine, into the CeA or dlBST, sections were processed with immunohistochemical reagents to localize the anterograde tracer and choline acetyltransferase (ChAT). The trajectories of efferent projections from CeA and dlBST were qualitatively similar. Few ChAT-immunoreactive (ir) neurons were present within the extended amygdala or regions containing the dense terminations of its efferent projections, with the striking exception of the caudal sublenticular/anterior amygdaloid region. The ChAT-ir neurons there, however, were significantly smaller and weakly ChAT-ir as compared to those located outside of the dense extended amygdaloid terminations. In the mesopontine tegmentum, the robust downstream projection from the extended amygdala was centered medial to ChAT-ir neurons of the pedunculopontine tegmental nucleus. The differentiated character of the relationships between extended amygdala and forebrain and mesopontine districts containing ChAT-ir neurons that give rise to ascending projections may have significant implications for the control of cortical and diencephalic acetylcholine release and accompanying effects on attention, vigilance and locomotor activation.
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Affiliation(s)
- Myriam Gastard
- Department of Anatomy and Neurobiology, St. Louis University School of Medicine, 1402 South Grand Boulevard, St. Louis, MO 63104, USA
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Auld DS, Kornecook TJ, Bastianetto S, Quirion R. Alzheimer's disease and the basal forebrain cholinergic system: relations to beta-amyloid peptides, cognition, and treatment strategies. Prog Neurobiol 2002; 68:209-45. [PMID: 12450488 DOI: 10.1016/s0301-0082(02)00079-5] [Citation(s) in RCA: 472] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Alzheimer's disease (AD) is the most common form of degenerative dementia and is characterized by progressive impairment in cognitive function during mid- to late-adult life. Brains from AD patients show several distinct neuropathological features, including extracellular beta-amyloid-containing plaques, intracellular neurofibrillary tangles composed of abnormally phosphorylated tau, and degeneration of cholinergic neurons of the basal forebrain. In this review, we will present evidence implicating involvement of the basal forebrain cholinergic system in AD pathogenesis and its accompanying cognitive deficits. We will initially discuss recent results indicating a link between cholinergic mechanisms and the pathogenic events that characterize AD, notably amyloid-beta peptides. Following this, animal models of dementia will be discussed in light of the relationship between basal forebrain cholinergic hypofunction and cognitive impairments in AD. Finally, past, present, and future treatment strategies aimed at alleviating the cognitive symptomatology of AD by improving basal forebrain cholinergic function will be addressed.
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Affiliation(s)
- Daniel S Auld
- Douglas Hospital Research Centre, 6875 Blvd Lasalle, Verdun, Que, Canada H4H 1R3
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Nakamura N, Fujita H, Kawata M. Effects of gonadectomy on immunoreactivity for choline acetyltransferase in the cortex, hippocampus, and basal forebrain of adult male rats. Neuroscience 2002; 109:473-85. [PMID: 11823060 DOI: 10.1016/s0306-4522(01)00513-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Androgens are known to affect cognitive and mnemonic aspects of spatial processing. The cholinergic system is thought to play an important role in cognition and memory, but little is known about the interaction between androgen and cholinergic neurons. The present study focused on the effects of testosterone on the cholinergic neurons in the anterior cingulate cortex, the posterior parietal cortex, the hippocampus, and the basal forebrain including the medial septum, i.e., regions related to spatial processing. We examined choline acetyltransferase (ChAT) immunoreactivity in three groups of adult male rats: sham-operated (Sham), 28-day gonadectomized (GDX), and 28-day gonadectomized with immediate implantation of testosterone propionate (GDX+TP). Comparison of the Sham and GDX+TP groups demonstrated that the GDX group had significantly decreased cell counts of ChAT-immunoreactive neurons in anterior cingulate cortex layer II/III, posterior parietal cortex layer II/III, and the medial septum, but not in the other basal forebrain subregions examined (the horizontal part of the diagonal band of Broca and the substantia innominata). The GDX group also had significantly reduced hippocampal ChAT-immunoreactive fiber pixel density. The GDX+TP group maintained ChAT-immunoreactive cell counts in the anterior cingulate cortex, posterior parietal cortex, and medial septum equivalent to those in the Sham group. Less than 1% of identified cells showed colocalization of immunoreactivity for ChAT and androgen receptor in the cell bodies of the cortex and basal forebrain. Our observations demonstrate that the presence or absence of testosterone for 4 weeks influenced the cholinergic population region-specifically in the adult rat brain.
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Affiliation(s)
- N Nakamura
- Department of Anatomy and Neurobiology, Kyoto Perfectural University of Medicine, Kyoto, Japan
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Ballmaier M, Casamenti F, Zoli M, Pepeu G, Spano P. Selective immunolesioning of cholinergic neurons in nucleus basalis magnocellularis impairs prepulse inhibition of acoustic startle. Neuroscience 2002; 108:299-305. [PMID: 11734362 DOI: 10.1016/s0306-4522(01)00413-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Information processing and attentional abnormalities are prominent in neuropsychiatric disorders. Since the cholinergic neurons located in the nucleus basalis magnocellularis have been shown to be involved in attentional performance and information processing, recent efforts to analyze the significance of the basal forebrain in the context of schizophrenia have focused on this nucleus and its projections to the cerebral cortex. We report here that bilateral selective immunolesioning of the cholinergic neurons in the nucleus basalis magnocellularis is followed by significant deficits in sensorimotor gating measured by prepulse inhibition of the startle reflex in adult rats. This behavioral approach is used in both humans and rodents and has been proposed as a valuable model contributing to the understanding of the neurobiological substrates of schizophrenia. The disruption of prepulse inhibition persisted over repeated testing. The selective lesions were induced by bilateral intraparenchymal infusions of 192 IgG saporin at a concentration having minimal diffusion into adjacent nuclei of the basal forebrain. The infusions were followed by extensive loss of choline acetyltransferase-immunopositive neurons. Our results show that the cholinergic neurons of the nucleus basalis magnocellularis represent a critical station of the startle gating circuitry and suggest that dysfunction of these neurons may result in impaired sensorimotor gating characteristic of schizophrenia.
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Affiliation(s)
- M Ballmaier
- Department of Biomedical Sciences and Biotechnologies, Brescia University Mecial School, Italy.
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Himmelheber AM, Sarter M, Bruno JP. The effects of manipulations of attentional demand on cortical acetylcholine release. BRAIN RESEARCH. COGNITIVE BRAIN RESEARCH 2001; 12:353-70. [PMID: 11689296 DOI: 10.1016/s0926-6410(01)00064-7] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In vivo microdialysis was used to measure acetylcholine (ACh) efflux in the frontoparietal cortex while rats performed in one of two operant tasks. One task was designed and validated to generate measures of sustained attention, while the other task was designed to minimize explicit demands on sustained attentional resources (low-demand task). Transferring animals from the baseline environment into the operant chambers robustly increased cortical ACh efflux regardless of subsequent task demands. Performance in the sustained attention task further increased frontoparietal ACh efflux, and these increases were not observed when animals were simply exposed to the operant chamber without task performance. Manipulations of the task parameters within a session, to either increase or decrease explicit demands on sustained attention, were not associated with fluctuations in ACh efflux. Unexpectedly, performance in the low-demand task was also associated with significant increases in ACh efflux that were similar to those observed during the sustained attention task. However, widespread depletions of cortical cholinergic inputs produced by intra-basalis infusions of 192 IgG-saporin failed to impair performance in the low-demand task, suggesting that cholinergic transmission is not necessary for performance in this task. The present results indicate that although a wider range of instrumental processes than previously hypothesized are associated with increases in cortical ACh release, the dependence of performance on the integrity of cortical cholinergic inputs may be limited to tasks with explicit attentional demands.
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Affiliation(s)
- A M Himmelheber
- Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
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Abstract
Previous studies showed a role for the amygdala central nucleus (CN) in attentional processing during the acquisition of Pavlovian associations. Both the acquisition of conditioned orienting responses and the surprise-induced enhancement in the ability of conditioned stimuli to enter into new associations depend on the integrity of CN. In this experiment, the role of CN in the performance of a well-learned selective attention task was examined. Rats with ibotenic acid lesions of CN and control rats first learned a discrete-trial, multiple-choice reaction time task. On each trial, after a constant-duration ready signal, the rats were required to poke their noses into one of three ports, guided by the brief illumination of one of those ports. Rats with CN lesions were slower to acquire the task than control rats but showed equivalent asymptotic sustained performance. Subsequent attentional challenges, which included reducing the duration of the port illumination and varying the duration of the ready signal, had greater impact on the performance of lesioned than control rats. These data resemble those reported from similar tasks after damage to the basal forebrain (BF) system. Together with earlier findings, these data support a role for CN in modulating visuospatial attention in action as well as in the acquisition of associations, perhaps by way of its projections to BF cholinergic systems.
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