1
|
Schoenfeld TJ, Smith JA, Sonti AN, Cameron HA. Adult neurogenesis alters response to an aversive distractor in a labyrinth maze without affecting spatial learning or memory. Hippocampus 2020; 31:102-114. [PMID: 33038042 DOI: 10.1002/hipo.23267] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 08/02/2020] [Accepted: 09/06/2020] [Indexed: 11/11/2022]
Abstract
Adult neurogenesis has been implicated in learning and memory of complex spatial environments. However, new neurons also play a role in nonmnemonic behavior, including the stress response and attention shifting. Many commonly used spatial tasks are very simple, and unsuitable for detecting neurogenesis effects, or are aversively motivated, making it difficult to dissociate effects on spatial learning and memory from effects on stress. We have therefore created a novel complex spatial environment, the flex maze, to enable reward-mediated testing of spatial learning in a flexibly configurable labyrinth. Using a pharmacogenetic method to completely inhibit neurogenesis in adulthood, we found that rats lacking new neurons (TK rats) and wild type controls completed and remembered most mazes equally well. However, control rats were slower to complete peppermint-scented mazes than other mazes, while neurogenesis-deficient rats showed no effect of mint on maze behavior, completing these mazes significantly faster than control rats. Additional testing found that wild type and TK rats showed similar detection of, avoidance of, and glucocorticoid response to the mint odor. These results suggest that spatial learning and memory in a labyrinth task is unaffected by the loss of new neurons, but that these cells affect the ability of an aversive stimulus to distract rats from completing the maze.
Collapse
Affiliation(s)
- Timothy J Schoenfeld
- Section on Neuroplasticity, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
| | - Jesse A Smith
- Section on Neuroplasticity, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
| | - Anup N Sonti
- Section on Neuroplasticity, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
| | - Heather A Cameron
- Section on Neuroplasticity, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
| |
Collapse
|
2
|
Barker GRI, Warburton EC. Putting objects in context: A prefrontal-hippocampal-perirhinal cortex network. Brain Neurosci Adv 2020; 4:2398212820937621. [PMID: 32954004 PMCID: PMC7479864 DOI: 10.1177/2398212820937621] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 06/05/2020] [Indexed: 11/15/2022] Open
Abstract
When we encounter an object, we spontaneously form associations between the
object and the environment in which it was encountered. These associations can
take a number of different forms, which include location and context. A neural
circuit between the hippocampus, medial prefrontal cortex and perirhinal cortex
is critical for object-location and object-sequence associations; however, how
this neural circuit contributes to the formation of object-context associations
has not been established. Bilateral lesions were made in the hippocampus, medial
prefrontal cortex or perirhinal cortex to examine each region contribution to
object-context memory formation. Next, a disconnection lesion approach was used
to examine the necessity of functional interactions between the hippocampus and
medial prefrontal cortex or perirhinal cortex. Spontaneous tests of preferential
exploration were used to assess memory for different types of object-context
associations. Bilateral lesion in the hippocampus, medial prefrontal cortex or
perirhinal cortex impaired performance in both an object-place-context and an
object-context task. Disconnection of the hippocampus from either the medial
prefrontal cortex or perirhinal cortex impaired performance in both the
object-place-context and object-context task. Interestingly, when object
recognition memory was tested with a context switch between encoding and test,
performance in the hippocampal and medial prefrontal cortex lesion groups was
disrupted and performance in each disconnection group (i.e. hippocampus + medial
prefrontal cortex, hippocampus + perirhinal cortex) was significantly impaired.
Overall, these experiments establish the importance of the hippocampal-medial
prefrontal-perirhinal cortex circuit for the formation of object-context
associations.
Collapse
Affiliation(s)
- G R I Barker
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - E C Warburton
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| |
Collapse
|
3
|
Kedrov AV, Mineyeva OA, Enikolopov GN, Anokhin KV. Involvement of Adult-born and Preexisting Olfactory Bulb and Dentate Gyrus Neurons in Single-trial Olfactory Memory Acquisition and Retrieval. Neuroscience 2019; 422:75-87. [DOI: 10.1016/j.neuroscience.2019.09.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 08/24/2019] [Accepted: 09/10/2019] [Indexed: 12/12/2022]
|
4
|
Ozubko JD, Moscovitch M, Winocur G. The influence of recollection and familiarity in the formation and updating of associative representations. Learn Mem 2017; 24:298-309. [PMID: 28620077 PMCID: PMC5473110 DOI: 10.1101/lm.045005.117] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 04/21/2017] [Indexed: 11/25/2022]
Abstract
Prior representations affect future learning. Little is known, however, about the effects of recollective or familiarity-based representations on such learning. We investigate the ability to reuse or reassociate elements from recollection- and familiarity-based associations to form new associations. Past neuropsychological research suggests that hippocampal, and presumably recollective, representations are more flexible than extra-hippocampal, presumably familiarity-based, representations. We therefore hypothesize that the elements of recollective associations, as opposed to familiarity-based representations, may be more easily manipulated and decoupled from each other, and facilitate the formation of new associations. To investigate this hypothesis we used the AB/AC learning paradigm. Across two recall studies we observed an advantage in learning AC word pairs if AB word pairs were initially recollected. Furthermore, AB word pairs were more likely to intrude during a final AC test if those AB word pairs were initially familiarity-based. A third experiment using a recognition version of the AB/AC paradigm ruled out the possibility that our findings were due to memory strength. Our results support the idea that elements in recollective associative traces may be more discretely coded, leading to their flexible use, whereas elements in familiarity-based associative traces are less flexible.
Collapse
Affiliation(s)
- Jason D Ozubko
- Department of Psychology, SUNY Geneseo, Geneseo, New York 14454, USA
| | - Morris Moscovitch
- Rotman Research Institute, Baycrest Centre, Toronto, Ontario M6A 2E1, Canada
| | - Gordon Winocur
- Rotman Research Institute, Baycrest Centre, Toronto, Ontario M6A 2E1, Canada
| |
Collapse
|
5
|
Lin TCE, Dumigan NM, Good M, Honey RC. Novel sensory preconditioning procedures identify a specific role for the hippocampus in pattern completion. Neurobiol Learn Mem 2016; 130:142-8. [PMID: 26911788 PMCID: PMC4826144 DOI: 10.1016/j.nlm.2016.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 02/02/2016] [Accepted: 02/05/2016] [Indexed: 12/03/2022]
Abstract
Successful retrieval of a memory for an entire pattern of stimulation by the presentation of a fragment of that pattern is a critical facet of memory function. We examined processes of pattern completion using novel sensory preconditioning procedures in rats that had either received sham lesions (group Sham) or lesions of the hippocampus (group HPC). After exposure to two audio-visual patterns (AX and BY) rats received fear conditioning with X (but not Y). Subsequent tests assessed fear to stimulus compounds (e.g., AX versus BX; Experiment 1) or elements (A versus B; Experiment 2). There was more fear to AX than BX in group Sham but not group HPC, while there was more fear to A than B in group HPC, but not in group Sham. This double dissociation suggests that pattern completion can be based upon separable processes that differ in their reliance on the hippocampus.
Collapse
Affiliation(s)
- Tzu-Ching E Lin
- School of Psychology, Cardiff University, Park Place, Cardiff CF10 3AT, UK
| | - Natasha M Dumigan
- School of Psychology, Cardiff University, Park Place, Cardiff CF10 3AT, UK
| | - Mark Good
- School of Psychology, Cardiff University, Park Place, Cardiff CF10 3AT, UK
| | - Robert C Honey
- School of Psychology, Cardiff University, Park Place, Cardiff CF10 3AT, UK.
| |
Collapse
|
6
|
Montgomery KS, Edwards G, Levites Y, Kumar A, Myers CE, Gluck MA, Setlow B, Bizon JL. Deficits in hippocampal-dependent transfer generalization learning accompany synaptic dysfunction in a mouse model of amyloidosis. Hippocampus 2016; 26:455-71. [PMID: 26418152 PMCID: PMC4803574 DOI: 10.1002/hipo.22535] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/11/2015] [Accepted: 09/17/2015] [Indexed: 11/08/2022]
Abstract
Elevated β-amyloid and impaired synaptic function in hippocampus are among the earliest manifestations of Alzheimer's disease (AD). Most cognitive assessments employed in both humans and animal models, however, are insensitive to this early disease pathology. One critical aspect of hippocampal function is its role in episodic memory, which involves the binding of temporally coincident sensory information (e.g., sights, smells, and sounds) to create a representation of a specific learning epoch. Flexible associations can be formed among these distinct sensory stimuli that enable the "transfer" of new learning across a wide variety of contexts. The current studies employed a mouse analog of an associative "transfer learning" task that has previously been used to identify risk for prodromal AD in humans. The rodent version of the task assesses the transfer of learning about stimulus features relevant to a food reward across a series of compound discrimination problems. The relevant feature that predicts the food reward is unchanged across problems, but an irrelevant feature (i.e., the context) is altered. Experiment 1 demonstrated that C57BL6/J mice with bilateral ibotenic acid lesions of hippocampus were able to discriminate between two stimuli on par with control mice; however, lesioned mice were unable to transfer or apply this learning to new problem configurations. Experiment 2 used the APPswe PS1 mouse model of amyloidosis to show that robust impairments in transfer learning are evident in mice with subtle β-amyloid-induced synaptic deficits in the hippocampus. Finally, Experiment 3 confirmed that the same transfer learning impairments observed in APPswePS1 mice were also evident in the Tg-SwDI mouse, a second model of amyloidosis. Together, these data show that the ability to generalize learned associations to new contexts is disrupted even in the presence of subtle hippocampal dysfunction and suggest that, across species, this aspect of hippocampal-dependent learning may be useful for early identification of AD-like pathology.
Collapse
Affiliation(s)
- Karienn S. Montgomery
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, Bryan, TX
| | - George Edwards
- Mitchell Center for Alzheimer’s Disease and Related Brain Disorders, Department of Neurology, University of Texas Health Science Center in Houston, Houston, TX
| | - Yona Levites
- Department of Neuroscience, University of Florida, Gainesville, FL
| | - Ashok Kumar
- Department of Neuroscience, University of Florida, Gainesville, FL
| | - Catherine E. Myers
- VA New Jersey Health Care System, East Orange, NJ 07018
- Department of Pharmacology, Physiology & Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ
| | - Mark A. Gluck
- Center for Molecular & Behavioral Neuroscience, Rutgers University, Newark, NJ
| | - Barry Setlow
- Department of Psychiatry, University of Florida, Gainesville, FL
| | | |
Collapse
|
7
|
Ketchum MJ, Weyand TG, Weed PF, Winsauer PJ. Learning by subtraction: Hippocampal activity and effects of ethanol during the acquisition and performance of response sequences. Hippocampus 2015; 26:601-22. [PMID: 26482846 DOI: 10.1002/hipo.22545] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 09/07/2015] [Accepted: 10/05/2015] [Indexed: 11/09/2022]
Abstract
Learning is believed to be reflected in the activity of the hippocampus. However, neural correlates of learning have been difficult to characterize because hippocampal activity is integrated with ongoing behavior. To address this issue, male rats (n = 5) implanted with electrodes (n = 14) in the CA1 subfield responded during two tasks within a single test session. In one task, subjects acquired a new 3-response sequence (acquisition), whereas in the other task, subjects completed a well-rehearsed 3-response sequence (performance). Both tasks though could be completed using an identical response topography and used the same sensory stimuli and schedule of reinforcement. More important, comparing neural patterns during sequence acquisition to those during sequence performance allows for a subtractive approach whereby activity associated with learning could potentially be dissociated from the activity associated with ongoing behavior. At sites where CA1 activity was closely associated with behavior, the patterns of activity were differentially modulated by key position and the serial position of a response within the schedule of reinforcement. Temporal shifts between peak activity and responding on particular keys also occurred during sequence acquisition, but not during sequence performance. Ethanol disrupted CA1 activity while producing rate-decreasing effects in both tasks and error-increasing effects that were more selective for sequence acquisition than sequence performance. Ethanol also produced alterations in the magnitude of modulations and temporal pattern of CA1 activity, although these effects were not selective for sequence acquisition. Similar to ethanol, hippocampal micro-stimulation decreased response rate in both tasks and selectively increased the percentage of errors during sequence acquisition, and provided a more direct demonstration of hippocampal involvement during sequence acquisition. Together, these results strongly support the notion that ethanol disrupts sequence acquisition by disrupting hippocampal activity and that the hippocampus is necessary for the conditioned associations required for sequence acquisition.
Collapse
Affiliation(s)
- Myles J Ketchum
- Department of Pharmacology and Experimental Therapeutics, LSU Health Sciences Center, New Orleans, Louisiana
| | - Theodore G Weyand
- Department Cell Biology and Anatomy, LSU Health Sciences Center, New Orleans, Louisiana
| | - Peter F Weed
- Department of Pharmacology and Experimental Therapeutics, LSU Health Sciences Center, New Orleans, Louisiana
| | - Peter J Winsauer
- Department of Pharmacology and Experimental Therapeutics, LSU Health Sciences Center, New Orleans, Louisiana.,Alcohol and Drug Abuse Center of Excellence, LSU Health Sciences Center, New Orleans, Louisiana
| |
Collapse
|
8
|
Marighetto A, Brayda-Bruno L, Etchamendy N. Studying the impact of aging on memory systems: contribution of two behavioral models in the mouse. Curr Top Behav Neurosci 2015; 10:67-89. [PMID: 21805395 DOI: 10.1007/7854_2011_151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In the present chapter, we describe our own attempts to improve our understanding of the pathophysiology of memory in aging. First, we tried to improve animal models of memory degradations occurring in aging, and develop common behavioral tools between mice and humans. Second, we began to use these behavioral tools to identify the molecular/intracellular changes occurring within the integrate network of memory systems in order to bridge the gap between the molecular and system level of analysis. The chapter is divided into three parts (i) modeling aging-related degradation in declarative memory (DM) in mice, (ii) assessing the main components of working memory (WM) with a common radial-maze task in mice and humans and (iii) studying the role of the retinoid cellular signaling path in aging-related changes in memory systems.
Collapse
Affiliation(s)
- Aline Marighetto
- Neurocentre Magendie-Inserm U862, 146 Rue Leo Saignat, 33077, Bordeaux-Cedex, France,
| | | | | |
Collapse
|
9
|
Martin-Fairey CA, Nunez AA. Circadian modulation of memory and plasticity gene products in a diurnal species. Brain Res 2014; 1581:30-9. [PMID: 25063362 PMCID: PMC4157103 DOI: 10.1016/j.brainres.2014.07.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 07/11/2014] [Accepted: 07/14/2014] [Indexed: 01/30/2023]
Abstract
Cognition is modulated by circadian rhythms, in both nocturnal and diurnal species. Rhythms of clock gene expression occur in brain regions that are outside the master circadian oscillator of the suprachiasmatic nucleus and that control cognitive functions, perhaps by regulating the expression neural-plasticity genes such as brain derived neurotrophic factor (BDNF) and its high affinity receptor, tyrosine kinase B (TrkB). In the diurnal grass rat (Arvicanthis niloticus), the hippocampus shows rhythms of clock genes that are 180° out of phase with those of nocturnal rodents. Here, we examined the hypothesis that this reversal extends to the optimal phase for learning a hippocampal-dependent task and to the phase of hippocampal rhythms in BDNF/TrkB expression. We used the Morris water maze (MWM) to test for time of day differences in reference memory and monitored daily patterns of hippocampal BDNF/TrkB expression in grass rats. Grass rats showed superior long-term retention of the MWM, when the training and testing occurred during the day as compared to the night, at a time when nocturnal laboratory rats show superior retention; acquisition of the MWM was not affected by time of day. BDNF/TrkB expression was rhythmic in the hippocampus of grass rats, and the phase of the rhythms was reversed compared to that of nocturnal rodents. Our findings provide correlational evidence for the claim that the circadian regulation of cognition may involve rhythms of BDNF/TrkB expression in the hippocampus and that their phase may contribute to species differences in the optimal phase for learning.
Collapse
Affiliation(s)
| | - Antonio A Nunez
- Department of Psychology, Michigan State University, East Lansing, MI 48824, USA; Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA.
| |
Collapse
|
10
|
Abstract
Different types of network oscillations occur in different behavioral, cognitive, or vigilance states. The rodent hippocampus expresses prominent θ oscillations at frequencies between 4 and 12 Hz, which are superimposed by phase-coupled γ oscillations (30-100 Hz). These patterns entrain multineuronal activity over large distances and have been implicated in sensory information processing and memory formation. Here we report a new type of oscillation at near-θ frequencies (2-4 Hz) in the hippocampus of urethane-anesthetized mice. The rhythm is highly coherent with nasal respiration and with rhythmic field potentials in the olfactory bulb: hence, we called it hippocampal respiration-induced oscillations. Despite the similarity in frequency range, several features distinguish this pattern from locally generated θ oscillations: hippocampal respiration-induced oscillations have a unique laminar amplitude profile, are resistant to atropine, couple differently to γ oscillations, and are abolished when nasal airflow is bypassed by tracheotomy. Hippocampal neurons are entrained by both the respiration-induced rhythm and concurrent θ oscillations, suggesting a direct interaction between endogenous activity in the hippocampus and nasal respiratory inputs. Our results demonstrate that nasal respiration strongly modulates hippocampal network activity in mice, providing a long-range synchronizing signal between olfactory and hippocampal networks.
Collapse
|
11
|
Rentz DM, Parra Rodriguez MA, Amariglio R, Stern Y, Sperling R, Ferris S. Promising developments in neuropsychological approaches for the detection of preclinical Alzheimer's disease: a selective review. ALZHEIMERS RESEARCH & THERAPY 2013; 5:58. [PMID: 24257331 PMCID: PMC3978443 DOI: 10.1186/alzrt222] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recently published guidelines suggest that the most opportune time to treat individuals with Alzheimer’s disease is during the preclinical phase of the disease. This is a phase when individuals are defined as clinically normal but exhibit evidence of amyloidosis, neurodegeneration and subtle cognitive/behavioral decline. While our standard cognitive tests are useful for detecting cognitive decline at the stage of mild cognitive impairment, they were not designed for detecting the subtle cognitive variations associated with this biomarker stage of preclinical Alzheimer’s disease. However, neuropsychologists are attempting to meet this challenge by designing newer cognitive measures and questionnaires derived from translational efforts in neuroimaging, cognitive neuroscience and clinical/experimental neuropsychology. This review is a selective summary of several novel, potentially promising, approaches that are being explored for detecting early cognitive evidence of preclinical Alzheimer’s disease in presymptomatic individuals.
Collapse
Affiliation(s)
- Dorene M Rentz
- Center for Alzheimer Research and Treatment, Departments of Neurology, Brigham and Women's Hospital and Massachusetts General Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
| | - Mario A Parra Rodriguez
- Department of Psychology, University of Edinburgh, Centre for Cognitive Aging and Cognitive Epidemiology, Alzheimer Scotland Dementia Research Centre and Scottish Dementia Clinical Research Network, 7 George Square, Edinburgh EH8 9JZ, UK
| | - Rebecca Amariglio
- Center for Alzheimer Research and Treatment, Departments of Neurology, Brigham and Women's Hospital and Massachusetts General Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
| | - Yaakov Stern
- Cognitive Neuroscience Division, Department of Neurology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | - Reisa Sperling
- Center for Alzheimer Research and Treatment, Departments of Neurology, Brigham and Women's Hospital and Massachusetts General Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
| | - Steven Ferris
- Alzheimer's Disease Center, Comprehensive Center for Brain Aging, Department of Psychiatry, NYU Langone Medical Center, 145 East 32nd Street, New York, NY 10016, USA
| |
Collapse
|
12
|
Fera F, Passamonti L, Herzallah MM, Myers CE, Veltri P, Morganti G, Quattrone A, Gluck MA. Hippocampal BOLD response during category learning predicts subsequent performance on transfer generalization. Hum Brain Mapp 2013; 35:3122-31. [PMID: 24142480 DOI: 10.1002/hbm.22389] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 07/03/2013] [Accepted: 07/30/2013] [Indexed: 11/07/2022] Open
Abstract
To test a prediction of our previous computational model of cortico-hippocampal interaction (Gluck and Myers [1993, 2001]) for characterizing individual differences in category learning, we studied young healthy subjects using an fMRI-adapted category-learning task that has two phases, an initial phase in which associations are learned through trial-and-error feedback followed by a generalization phase in which previously learned rules can be applied to novel associations (Myers et al. [2003]). As expected by our model, we found a negative correlation between learning-related hippocampal responses and accuracy during transfer, demonstrating that hippocampal adaptation during learning is associated with better behavioral scores during transfer generalization. In addition, we found an inverse relationship between Blood Oxygenation Level Dependent (BOLD) activity in the striatum and that in the hippocampal formation and the orbitofrontal cortex during the initial learning phase. Conversely, activity in the dorsolateral prefrontal cortex, orbitofrontal cortex and parietal lobes dominated over that of the hippocampal formation during the generalization phase. These findings provide evidence in support of theories of the neural substrates of category learning which argue that the hippocampal region plays a critical role during learning for appropriately encoding and representing newly learned information so that that this learning can be successfully applied and generalized to subsequent novel task demands.
Collapse
Affiliation(s)
- Francesco Fera
- Department of Surgical and Medical Sciences, University "Magna Graecia", 88100, Catanzaro, Italy
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Affiliation(s)
- Robert Jaffard
- Laboratoire de Neurosciences Comportementales et Cognitives, Université de Bordeaux I, France
| | - Martine Meunier
- Laboratoire de Neurosciences Comportementales et Cognitives, Université de Bordeaux I, France
| |
Collapse
|
14
|
Bachevalier J, Wright AA, Katz JS. Serial position functions following selective hippocampal lesions in monkeys: effects of delays and interference. Behav Processes 2013; 93:155-66. [PMID: 23246643 PMCID: PMC3684055 DOI: 10.1016/j.beproc.2012.11.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 11/12/2012] [Accepted: 11/26/2012] [Indexed: 11/25/2022]
Abstract
We examined the role of the hippocampus in list-memory processing. Three rhesus monkeys that had extensive experience in this task and had demonstrated full abstract-concept learning and excellent list memory performance (Katz et al., 2002; Wright et al., 2003) received bilateral neurotoxic hippocampal lesions and were re-tested in the serial list memory task. Effects of delays on memory performance were measured in all monkeys, whereas the effects of proactive interference were assessed in only one. Despite a slight change in performance of one of the three animals during re-learning of the same/different task, selective hippocampal damage had little or no effects on list memory accuracy. In addition, the hippocampal damage did not impact serial list position functions (SPFs) but slightly altered the dynamic of the SPF curves. Finally, even more remarkable was that accurate memory performance of one animal remained intact despite the use of small set size of 8 items that created high proactive interference across lists thereby eliminating any use of familiarity judgments to support performance. Together the findings indicate that, with short list items and extensive training in the task (i.e., reference memory), monkeys with selective hippocampal lesions may be able to use alternative memory processes (i.e., working memory) that are mediated by structures other than the hippocampus.
Collapse
Affiliation(s)
- Jocelyne Bachevalier
- Department of Anatomy and Neurobiology, University of Texas, Health Science Center-Houston, TX, USA.
| | | | | |
Collapse
|
15
|
Abstract
Plasticity in the adult brain enables lifelong learning. The fundamental mechanism of adult neural plasticity is activity-dependent reorganization of pre-existing structure, in contrast to the widespread cellular proliferation and migration that occurs during development. Whereas adult hippocampal dentate gyrus continuously generates cohorts of neurons, and newborn neurons integrate into the existing neural circuit under the regulation of existing global and local neural activity, demonstrating a unique cellular and synaptic flexibility in adult brain. Exhibiting an enhanced structural and synaptic plasticity during the maturation, adult-born hippocampal neurons may represent a unique population for hippocampal function. Current evidence indicates that lifelong addition of new hippocampal neurons may extend early developmental plasticity to adulthood, which continuously rejuvenates adult brain. We reviewed most recent advancements in exploring the circuit and behavioral role of adult-born hippocampal neurons.
Collapse
Affiliation(s)
- Yan Gu
- Department of Neurobiology and Behavior, Stony Brook University, 100 Nicolls Road, Stony Brook, NY, 11794, USA,
| | | | | |
Collapse
|
16
|
Hunsaker MR, Kesner RP. The operation of pattern separation and pattern completion processes associated with different attributes or domains of memory. Neurosci Biobehav Rev 2012; 37:36-58. [PMID: 23043857 DOI: 10.1016/j.neubiorev.2012.09.014] [Citation(s) in RCA: 167] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Revised: 09/19/2012] [Accepted: 09/26/2012] [Indexed: 12/21/2022]
Abstract
Pattern separation and pattern completion processes are central to how the brain processes information in an efficient manner. Research into these processes is escalating and deficient pattern separation is being implicated in a wide array of genetic disorders as well as in neurocognitive aging. Despite the quantity of research, there remains a controversy as to precisely which behavioral paradigms should be used to best tap into pattern separation and pattern completion processes, as well as to what constitute legitimate outcome measures reflecting impairments in pattern separation and pattern completion. This review will discuss a theory based on multiple memory systems that provides a framework upon which behavioral tasks can be designed and their results interpreted. Furthermore, this review will discuss the nature of pattern separation and pattern completion and extend these processes outside the hippocampus and across all domains of information processing. After these discussions, an optimal strategy for designing behavioral paradigms to evaluate pattern separation and pattern completion processes will be provided.
Collapse
Affiliation(s)
- Michael R Hunsaker
- Department of Psychiatry and Behavioral Sciences, MIND Institute, University of California, Davis Medical Center, 2805 50th Street, Room 1415, Sacramento, CA 95817, USA.
| | | |
Collapse
|
17
|
Krishna R, Moustafa AA, Eby A, Skeen LC, Myers CE. Learning and generalization in healthy aging: implication for frontostriatal and hippocampal function. Cogn Behav Neurol 2012; 25:7-15. [PMID: 22353726 PMCID: PMC3361711 DOI: 10.1097/wnn.0b013e318248ff1b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Damage to the hippocampal and frontostriatal systems can occur across the adult life span. As these 2 systems are involved in learning processes, mild impairments of learning and generalization might be observed even in healthy aging. In this study, we examined both learning and generalization performance in 3 groups of older adults: young-older (ages 45 to 60 y), middle-older (ages 61 to 75 y), and oldest-older (ages 76 to 90 y). We used a simple computerized concurrent discrimination task in which the learning phase has shown sensitivity to frontostriatal dysfunction, and the generalization phase to hippocampal damage. We found that age significantly affected initial learning performance, but generalization was spared in all but the oldest group, with some individuals still generalizing very well. This finding suggests that (a) learning abilities are affected in healthy aging (consistent with earlier reports of frontostriatal dysfunction in healthy aging) and (b) generalization deficit does not necessarily occur in early older age. We hypothesize that generalization deficits in some in the oldest group may be related to hippocampal pathology. Our data shed light on possible neural system dysfunction in healthy aging and Alzheimer disease.
Collapse
Affiliation(s)
- Rakhee Krishna
- University of Medicine and Dentistry of New Jersey, Piscataway, NJ
| | - Ahmed A. Moustafa
- Rutgers University, Newark, NJ
- School of Psychology, University of Western Sydney, Sydney, Australia
| | - Alan Eby
- Bridgewater College, Bridgewater, VA
| | | | - Catherine E. Myers
- Rutgers University, Newark, NJ
- Department of Veterans Affairs-New Jersey Health Care System, East Orange, NJ
| |
Collapse
|
18
|
New approach illuminates how memory systems switch. Trends Cogn Sci 2012; 16:102-3. [DOI: 10.1016/j.tics.2011.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 11/23/2011] [Indexed: 11/23/2022]
|
19
|
Sanderson DJ, Rawlins JNP, Deacon RMJ, Cunningham C, Barkus C, Bannerman DM. Hippocampal lesions can enhance discrimination learning despite normal sensitivity to interference from incidental information. Hippocampus 2011; 22:1553-66. [PMID: 22161993 PMCID: PMC3506972 DOI: 10.1002/hipo.20995] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/25/2011] [Indexed: 11/13/2022]
Abstract
Spatial properties of stimuli are sometimes encoded even when incidental to the demands of a particular learning task. Incidental encoding of spatial information may interfere with learning by (i) causing a failure to generalize learning between trials in which a cue is presented in different spatial locations and (ii) adding common spatial features to stimuli that predict different outcomes. Hippocampal lesions have been found to facilitate acquisition of certain tasks. This facilitation may occur because hippocampal lesions impair incidental encoding of spatial information that interferes with learning. To test this prediction mice with lesions of the hippocampus were trained on appetitive simple simultaneous discrimination tasks using inserts in the goal arms of a T-maze. It was found that hippocampal lesioned mice were facilitated at learning the discriminations, but they were sensitive to changes in spatial information in a manner that was similar to control mice. In a second experiment it was found that both control and hippocampal lesioned mice showed equivalent incidental encoding of egocentric spatial properties of the inserts, but both groups did not encode the allocentric information. These results demonstrate that mice show incidental encoding of egocentric spatial information that decreases the ability to solve simultaneous discrimination tasks. The normal egocentric spatial encoding in hippocampal lesioned mice contradicts theories of hippocampal function that suggest that the hippocampus is necessary for incidental learning per se, or is required for modulating stimulus representations based on the relevancy of information. The facilitated learning suggests that the hippocampal lesions can enhance learning of the same qualitative information as acquired by control mice. © 2011 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- David J Sanderson
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom.
| | | | | | | | | | | |
Collapse
|
20
|
Montgomery KS, Simmons RK, Edwards G, Nicolle MM, Gluck MA, Myers CE, Bizon JL. Novel age-dependent learning deficits in a mouse model of Alzheimer's disease: implications for translational research. Neurobiol Aging 2011; 32:1273-85. [PMID: 19720431 PMCID: PMC4334376 DOI: 10.1016/j.neurobiolaging.2009.08.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Revised: 07/27/2009] [Accepted: 08/03/2009] [Indexed: 11/28/2022]
Abstract
Computational modeling predicts that the hippocampus plays an important role in the ability to apply previously learned information to novel problems and situations (referred to as the ability to generalize information or simply as 'transfer learning'). These predictions have been tested in humans using a computer-based task on which individuals with hippocampal damage are able to learn a series of complex discriminations with two stimulus features (shape and color), but are impaired in their ability to transfer this information to newly configured problems in which one of the features is altered. This deficit occurs despite the fact that the feature predictive of the reward (the relevant information) is not changed. The goal of the current study was to develop a mouse analog of transfer learning and to determine if this new task was sensitive to pathological changes in a mouse model of AD. We describe a task in which mice were able to learn a series of concurrent discriminations that contained two stimulus features (odor and digging media) and could transfer this learned information to new problems in which the irrelevant feature in each discrimination pair was altered. Moreover, we report age-dependent deficits specific to transfer learning in APP+PS1 mice relative to non-transgenic littermates. The robust impairment in transfer learning may be more sensitive to AD-like pathology than traditional cognitive assessments in that no deficits were observed in the APP+PS1 mice on the widely used Morris water maze task. These data describe a novel and sensitive paradigm to evaluate mnemonic decline in AD mouse models that has unique translational advantages over standard species-specific cognitive assessments (e.g., water maze for rodent and delayed paragraph recall for humans).
Collapse
Affiliation(s)
- K. S. Montgomery
- Behavioral and Cellular Neuroscience, Dept. Psychology, Texas A&M University, College Station, TX 77843-4235, , , ,
| | - R. K. Simmons
- Behavioral and Cellular Neuroscience, Dept. Psychology, Texas A&M University, College Station, TX 77843-4235, , , ,
| | - G. Edwards
- Behavioral and Cellular Neuroscience, Dept. Psychology, Texas A&M University, College Station, TX 77843-4235, , , ,
| | - M. M. Nicolle
- Internal Medicine Gerontology and Dept. of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157,
| | - M. A. Gluck
- Center for Molecular & Behavioral Neuroscience, Rutgers University, Newark, NJ 07102-1896,
| | - C. E. Myers
- Department of Psychology, Rutgers University, Newark, NJ 08854-8020,
| | - J. L. Bizon
- Behavioral and Cellular Neuroscience, Dept. Psychology, Texas A&M University, College Station, TX 77843-4235, , , ,
- Faculty of Neuroscience, Texas A&M University, College Station, TX 77843-4235
| |
Collapse
|
21
|
Henke K. A model for memory systems based on processing modes rather than consciousness. Nat Rev Neurosci 2011; 11:523-32. [PMID: 20531422 DOI: 10.1038/nrn2850] [Citation(s) in RCA: 356] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Prominent models of human long-term memory distinguish between memory systems on the basis of whether learning and retrieval occur consciously or unconsciously. Episodic memory formation requires the rapid encoding of associations between different aspects of an event which, according to these models, depends on the hippocampus and on consciousness. However, recent evidence indicates that the hippocampus mediates rapid associative learning with and without consciousness in humans and animals, for long-term and short-term retention. Consciousness seems to be a poor criterion for differentiating between declarative (or explicit) and non declarative (or implicit) types of memory. A new model is therefore required in which memory systems are distinguished based on the processing operations involved rather than by consciousness.
Collapse
Affiliation(s)
- Katharina Henke
- University of Bern, Muesmattstrasse 45,3000 Bern 9, Switzerland.
| |
Collapse
|
22
|
Valerio S, Clark BJ, Chan JHM, Frost CP, Harris MJ, Taube JS. Directional learning, but no spatial mapping by rats performing a navigational task in an inverted orientation. Neurobiol Learn Mem 2010; 93:495-505. [PMID: 20109566 PMCID: PMC2862784 DOI: 10.1016/j.nlm.2010.01.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 01/01/2010] [Accepted: 01/20/2010] [Indexed: 11/30/2022]
Abstract
Previous studies have identified neurons throughout the rat limbic system that fire as a function of the animal's head direction (HD). This HD signal is particularly robust when rats locomote in the horizontal and vertical planes, but is severely attenuated when locomoting upside-down (Calton & Taube, 2005). Given the hypothesis that the HD signal represents an animal's sense of directional heading, we evaluated whether rats could accurately navigate in an inverted (upside-down) orientation. The task required the animals to find an escape hole while locomoting inverted on a circular platform suspended from the ceiling. In Experiment 1, Long-Evans rats were trained to navigate to the escape hole by locomoting from either one or four start points. Interestingly, no animals from the 4-start point group reached criterion, even after 29 days of training. Animals in the 1-start point group reached criterion after about six training sessions. In Experiment 2, probe tests revealed that animals navigating from either 1- or 2-start points utilized distal visual landmarks for accurate orientation. However, subsequent probe tests revealed that their performance was markedly attenuated when navigating to the escape hole from a novel start point. This absence of flexibility while navigating upside-down was confirmed in Experiment 3 where we show that the rats do not learn to reach a place, but instead learn separate trajectories to the target hole(s). Based on these results we argue that inverted navigation primarily involves a simple directional strategy based on visual landmarks.
Collapse
Affiliation(s)
| | | | - Jeremy H. M. Chan
- Department of Psychological and Brain Sciences, Dartmouth College, 6207 Moore Hall, Hanover, NH 03755
| | - Carlton P. Frost
- Department of Psychological and Brain Sciences, Dartmouth College, 6207 Moore Hall, Hanover, NH 03755
| | - Mark J. Harris
- Department of Psychological and Brain Sciences, Dartmouth College, 6207 Moore Hall, Hanover, NH 03755
| | - Jeffrey S. Taube
- Department of Psychological and Brain Sciences, Dartmouth College, 6207 Moore Hall, Hanover, NH 03755
| |
Collapse
|
23
|
Does it still make sense to develop a declarative memory theory of hippocampal function? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00035615] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
24
|
What can neuroanatomy tell us about the functional components of the hippocampal memory system? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00035652] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
25
|
|
26
|
|
27
|
|
28
|
Is Eichenbaum et al.'s proposal testable and how extensive is the hippocampal memory system? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00035408] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
29
|
|
30
|
|
31
|
|
32
|
|
33
|
|
34
|
|
35
|
Functional distinctions within the medical temporal lobe memory system: What is the evidence? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00035640] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
36
|
|
37
|
Abstract
AbstractThere is considerable evidence that the hippocampal system contributes both to (1) the temporary maintenance of memories and to (2) the processing of a particular type of memory representation. The findings on amnesia suggest that these two distinguishing features of hippocampal memory processing are orthogonal. Together with anatomical and physiological data, the neuropsychological findings support a model of cortico-hippocampal interactions in which the temporal and representational properties of hippocampal memory processing are mediated separately. We propose that neocortical association areas maintain shortterm memories for specific items and events prior to hippocampal processing as well as providing the final repositories of long-term memory. The parahippocampal region supports intermediate-term storage of individual items, and the hippocampal formation itself mediates an organization of memories according to relevant relationships among items. Hippocampal-cortical interactions produce (i) strong and persistent memories for events, including their constituent elements and the relationships among them, and (ii) a capacity to express memories flexibly across a wide range of circumstances.
Collapse
|
38
|
Krebs-Kraft DL, Parent MB. Septal co-infusions of glucose with the benzodiazepine agonist chlordiazepoxide impair memory, but co-infusions of glucose with the opiate morphine do not. Physiol Behav 2009; 99:438-44. [PMID: 20005883 DOI: 10.1016/j.physbeh.2009.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 11/24/2009] [Accepted: 12/04/2009] [Indexed: 10/20/2022]
Abstract
We have found repeatedly that medial septal (MS) infusions of glucose impair memory when co-infused with the gamma-amino butyric acid (GABA) agonist muscimol. The present experiments sought to determine whether the memory-impairing effects of this concentration of glucose would generalize to another GABA(A) receptor agonist and to an agonist from another neurotransmitter system that is known to impair memory. Specifically, we determined whether the dose of glucose that produces memory deficits when combined with muscimol in the MS would also impair memory when co-infused with the GABA(A) receptor modulator chlordiazepoxide (CDP) or the opiate morphine. Male Sprague-Dawley rats were given MS co-infusions and then 15 min later tested for spontaneous alternation or given shock avoidance training (retention tested 48 h later). The results showed that MS infusions of the higher dose of glucose with morphine did not produce memory deficits, whereas, the performance of rats given MS co-infusions of CDP with glucose was impaired. These findings suggest that the memory-impairing effects of brain glucose administration may involve an interaction with the GABA(A) receptor.
Collapse
Affiliation(s)
- Desiree L Krebs-Kraft
- Department of Psychology and Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA 30303, USA.
| | | |
Collapse
|
39
|
Lasarge CL, Bañuelos C, Mayse JD, Bizon JL. Blockade of GABA(B) receptors completely reverses age-related learning impairment. Neuroscience 2009; 164:941-7. [PMID: 19723562 PMCID: PMC2874897 DOI: 10.1016/j.neuroscience.2009.08.055] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Revised: 08/21/2009] [Accepted: 08/22/2009] [Indexed: 11/16/2022]
Abstract
Impaired cognitive functions are well-described in the aging process. GABA(B) antagonists can facilitate learning and memory in young subjects, but these agents have not been well-characterized in aging. Here we show a complete reversal of olfactory discrimination learning deficits in cognitively-impaired aged Fischer 344 rats using the GABA(B) antagonist CGP55845, such that drug treatment restored performance to that on par with young and cognitively-unimpaired aged subjects. There was no evidence that this improved learning was due to enhanced olfactory detection abilities produced by the drug. These results highlight the potential of targeting GABA(B) receptors to ameliorate age-related cognitive deficits and demonstrate the utility of olfactory discrimination learning as a preclinical model for testing novel therapies to improve cognitive functions in aging.
Collapse
Affiliation(s)
- C L Lasarge
- Department of Psychology and Faculty of Neuroscience, Texas A&M University, College Station, TX 77843-4235, USA
| | | | | | | |
Collapse
|
40
|
Associative Learning, Acquired Equivalence, and Flexible Generalization of Knowledge in Mild Alzheimer Disease. Cogn Behav Neurol 2009; 22:89-94. [DOI: 10.1097/wnn.0b013e318192ccf0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
41
|
Manrique T, Morón I, Ballesteros MA, Guerrero RM, Fenton AA, Gallo M. Hippocampus, aging, and segregating memories. Hippocampus 2009; 19:57-65. [DOI: 10.1002/hipo.20481] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
42
|
Abstract
Studies of the medial temporal lobe and basal ganglia memory systems have recently been extended towards understanding the neural systems contributing to category learning. The basal ganglia, in particular, have been linked to probabilistic category learning in humans. A separate parallel literature in systems neuroscience has emerged, indicating a role for the basal ganglia and related dopamine inputs in reward prediction and feedback processing. Here, we review behavioral, neuropsychological, functional neuroimaging, and computational studies of basal ganglia and dopamine contributions to learning in humans. Collectively, these studies implicate the basal ganglia in incremental, feedback-based learning that involves integrating information across multiple experiences. The medial temporal lobes, by contrast, contribute to rapid encoding of relations between stimuli and support flexible generalization of learning to novel contexts and stimuli. By breaking down our understanding of the cognitive and neural mechanisms contributing to different aspects of learning, recent studies are providing insight into how, and when, these different processes support learning, how they may interact with each other, and the consequence of different forms of learning for the representation of knowledge.
Collapse
|
43
|
Immunotoxic cholinergic lesions in the basal forebrain reverse the effects of entorhinal cortex lesions on conditioned odor aversion in the rat. Neurobiol Learn Mem 2007; 88:114-26. [DOI: 10.1016/j.nlm.2007.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Revised: 01/23/2007] [Accepted: 01/25/2007] [Indexed: 11/20/2022]
|
44
|
Nagy H, Kéri S, Myers CE, Benedek G, Shohamy D, Gluck MA. Cognitive sequence learning in Parkinson's disease and amnestic mild cognitive impairment: Dissociation between sequential and non-sequential learning of associations. Neuropsychologia 2007; 45:1386-92. [PMID: 17188311 DOI: 10.1016/j.neuropsychologia.2006.10.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2006] [Revised: 10/27/2006] [Accepted: 10/30/2006] [Indexed: 11/24/2022]
Abstract
Evidence suggests that dopaminergic mechanisms in the basal ganglia (BG) are important in the learning of sequential associations. To test the specificity of this hypothesis, we assessed never-medicated patients with Parkinson's disease (PD) and amnestic mild cognitive impairment (aMCI) using a chaining task. In the training phase of the chaining task, each link in a sequence of stimuli leading to reward is trained step-by-step using feedback after each decision, until the complete sequence is learned. In the probe phase of the chaining task, the context of stimulus-response associations must be used (the position of the associations in the sequence). Results revealed that patients with PD showed impaired learning during the training phase of the chaining task, but their performance was spared in the probe phase. In contrast, patients with aMCI with prominent medial temporal lobe (MTL) dysfunctions showed intact learning during the training phase of the chaining task, but their performance was impaired in the probe phase of the chaining task. These results indicate that when dopaminergic mechanisms in the BG are dysfunctional, series of stimulus-response associations are less efficiently acquired, but their sequential manner is maintained. In contrast, MTL dysfunctions may result in a non-sequential learning of associations, which may indicate a loss of contextual information.
Collapse
Affiliation(s)
- Helga Nagy
- University of Szeged, Department of Neurology, Szeged, Hungary
| | | | | | | | | | | |
Collapse
|
45
|
Abstract
The transverse patterning (TP) task (A+ B-, B+ C-, C+ A-) has played a central role in testing the hypothesis that medial-temporal (and, in particular, hippocampal) brain damage selectively impairs learning on at least some classes of configural (i.e., nonlinear) learning tasks. Results in the animal and human literature generally support that hypothesis. Reed and Squire [Impaired transverse patterning in human amnesia is a special case of impaired memory for two-choice discrimination tasks. Behavioral Neuroscience, 113, 3-9, 1999], however, advanced an alternative account in which impaired TP performance in amnesia reflects a generic scaling artifact arising from the greater difficulty of the TP task compared to the elemental (i.e., linear) control task that is typically used. We begin with a critique of Reed and Squire, countering their conceptual arguments and showing that their results, when analyzed appropriately, support the configural deficit hypothesis. We then report results from eight new amnesic patients and controls on an improved version of the TP task. Despite substantial practice, accuracy of patients with bilateral hippocampal damage due to anoxia reached and maintained an asymptote of only 54% correct, well below the maximum accuracy obtainable (67%) in the absence of configural learning. A patient with selective bilateral damage to the anterior thalamic nuclei exhibited a TP accuracy asymptote that was near 67%, a pattern of two out of three correct consecutive trials, and a pattern of nearly always answering correctly for two of the three TP item pairs. These results are consistent with a set of unique and parameter-free predictions of the configural deficit hypothesis.
Collapse
Affiliation(s)
- Timothy C Rickard
- Department of Psychology, University of California, San Diego, La Jolla 92093, USA.
| | | | | |
Collapse
|
46
|
Gluck MA, Myers C, Meeter M. Cortico-hippocampal interaction and adaptive stimulus representation: a neurocomputational theory of associative learning and memory. Neural Netw 2005; 18:1265-79. [PMID: 16275027 DOI: 10.1016/j.neunet.2005.08.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Computational models of the hippocampal region link psychological theories of associative learning with their underlying physiological and anatomical substrates. Our approach to theory development began with a broad description of the computations that depend on the hippocampal region in classical conditioning (Gluck and Myers, 1993 and Gluck and Myers, 2001). In this initial model, the hippocampal region was treated as an Information-processing system that transformed stimulus representations, compressing (making more similar) representations of inputs that co-occur or are otherwise redundant, while differentiating (or making less similar) representations of inputs that predict different future events. This model led to novel predictions for the behavioral consequences of hippocampal-region lesions in rodents and of brain damage in humans who have amnesia or are in the earliest stages of Alzheimer's disease. Many of these predictions have, since been confirmed by our lab and others. Functional brain imaging studies have provided further supporting evidence. In more recent computational modeling, we have shown how some aspects of this proposed information-processing function could emerge from known anatomical and physiological characteristics of the hippocampal region, including the entorhinal cortex and the septo-hippocampal cholinergic system. The modeling to date lays the groundwork for future directions that increase the depth of detail of the biological modeling, as well as the breadth of behavioral phenomena addressed. In particular, we are working now to reconcile these kinds of incremental associative learning models with other models of the hippocampal region that account for the rapid formation of declarative memories.
Collapse
Affiliation(s)
- Mark A Gluck
- Center for Molecular and Behavioral Neuroscience, Rutgers University-Newark, Newark, NJ 07102, USA.
| | | | | |
Collapse
|
47
|
Shohamy D, Myers CE, Geghman KD, Sage J, Gluck MA. L-dopa impairs learning, but spares generalization, in Parkinson's disease. Neuropsychologia 2005; 44:774-84. [PMID: 16150469 PMCID: PMC1626444 DOI: 10.1016/j.neuropsychologia.2005.07.013] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 07/14/2005] [Accepted: 07/21/2005] [Indexed: 10/25/2022]
Abstract
In this study we examined the effect of dopaminergic modulation on learning and memory. Parkinson's patients were tested 'on' versus 'off' dopaminergic medication, using a two-phase learning and transfer task. We found that dopaminergic medication was associated with impaired learning of an incrementally acquired concurrent discrimination task, while patients withdrawn from dopaminergic medication performed as well as controls. In addition, we found a dissociation of the effect of medication within a single two-phase task: patients tested 'on' medication were not impaired at the ability to generalize based on learned information. The deficit among medicated patients appeared to be related specifically to the concurrent, incremental, feedback-based nature of the task: such a deficit was not found in a version of the task in which demands for concurrent error-processing learning were reduced. Taken together with a growing body of evidence emphasizing a role for midbrain dopamine in error-correcting, feedback-based learning processes, the present results suggest a framework for understanding previously conflicting results regarding the effect of medication on learning and memory in Parkinson's disease.
Collapse
Affiliation(s)
- Daphna Shohamy
- Department of Psychology, Stanford University, Jordan Hall, Bldg. 420, Stanford, CA 94305, USA.
| | | | | | | | | |
Collapse
|
48
|
Hu D, Xu X, Gonzalez-Lima F. Hippocampal cytochrome oxidase activity of rats in easy and difficult visual discrimination learning. Int J Neurosci 2005; 115:595-611. [PMID: 15823927 DOI: 10.1080/00207450590523440] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The present study investigated the functional involvement of the rat hippocampal formation in easy and difficult visual discrimination learning by measuring regional brain cytochrome oxidase (C.O.) activity, an index of neuronal metabolic activity. The results showed that learning was related to C.O. activity in the CA field and the dentate gyrus of the hippocampal formation of rats in the difficult discrimination, whereas learning was related to C.O. activity only in the dentate gyrus of rats in the easy discrimination. The results suggest that difficult visual discrimination learning required greater involvement of the hippocampal formation than easy visual discrimination learning.
Collapse
Affiliation(s)
- Dan Hu
- McGovern Institute for Brain Research, MIT, Cambridge, Massachusetts 02139, USA.
| | | | | |
Collapse
|
49
|
Countryman RA, Orlowski JD, Brightwell JJ, Oskowitz AZ, Colombo PJ. CREB phosphorylation and c-Fos expression in the hippocampus of rats during acquisition and recall of a socially transmitted food preference. Hippocampus 2005; 15:56-67. [PMID: 15390165 DOI: 10.1002/hipo.20030] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In the present study, phosphorylation of cAMP-response element binding protein (pCREB) and expression of c-Fos were measured in the dorsal and ventral hippocampus, as well as in a control region, the retrosplenial cortex, of rats following acquisition and recall of a socially transmitted food preference (STFP). Behavioral analyses revealed that STFP-trained rats showed a stronger preference for the demonstrated food than did rats in social-control or odor-control conditions. Rats in a social + odor control condition displayed an intermediate preference that was not significantly different from either STFP-trained rats or the social- or odor-controls. Immunocytochemical analyses revealed increased pCREB-immunoreactivity (ir) in the ventral hippocampus of STFP-trained rats in comparisons with rats in all three control conditions and increased pCREB-ir in the dorsal hippocampus in comparisons with the social- and odor-control conditions. In contrast, c-Fos-ir was greater in the dorsal hippocampus of STFP-trained rats in comparisons with all three control conditions and greater in the ventral hippocampus than rats in the social- and odor-control conditions. Comparisons of pCREB-ir and c-Fos-ir were made also between STFP-trained rats and social-controls following either acquisition or a 48-h recall test. c-Fos-ir was greater in STFP-trained rats after both acquisition and recall, whereas pCREB was greater after recall only. There were no differences in either c-Fos-ir or pCREB-ir in comparisons between trained and control rats in the retrosplenial cortex. The current results indicate that the activity of transcription factors in the hippocampus is related to both acquisition and retention of a socially transmitted food preference.
Collapse
Affiliation(s)
- Renee A Countryman
- Department of Psychology, Tulane University, New Orleans, Louisiana 70118, USA
| | | | | | | | | |
Collapse
|
50
|
Golan HM, Lev V, Hallak M, Sorokin Y, Huleihel M. Specific neurodevelopmental damage in mice offspring following maternal inflammation during pregnancy. Neuropharmacology 2005; 48:903-17. [PMID: 15829260 DOI: 10.1016/j.neuropharm.2004.12.023] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Revised: 11/02/2004] [Accepted: 12/10/2004] [Indexed: 10/25/2022]
Abstract
Intrauterine inflammation is a major risk for offspring neurodevelopmental brain damage and may result in cognitive limitations and poor cognitive and perceptual outcomes. Pro-inflammatory cytokines, stimulated during inflammatory response, have a pleotrophic effect on neurons and glia cells. They act in a dose-dependent manner, activate cell-death pathways and also act as trophic factors. In the present study, we have examined in mice the effect of short, systemic maternal inflammation on fetal brain development. Maternal inflammation, induced by lipopolysaccharide (LPS) at gestation day 17, did not affect morphogenic parameters and reflex development during the first month of life. However, maternal inflammation specifically increased the number of pyramidal and granular cells in the hippocampus, as well as the shrinkage of pyramidal cells, but not of the granular cells. No additional major morphological differences were observed in the cerebral cortex or cerebellum. In accordance with the morphological effects, maternal inflammation specifically impaired distinct forms of learning and memory, but not motor function or exploration in the adult offspring. The specific deficiency observed, following maternal inflammation, may suggest particular sensitivity of the hippocampus and other associated brain regions to inflammatory factors during late embryonic development.
Collapse
Affiliation(s)
- H M Golan
- Department of Developmental Molecular Genetics and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
| | | | | | | | | |
Collapse
|