Cognitive neuroscience

Non-invasive canine electroencephalography (EEG): a systematic review

The emerging field of canine cognitive neuroscience uses neuroimaging tools such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to map the cognitive processes of dogs to neural substrates in their brain. Within the past decade, the non-invasive use of EEG has provided real-time, accessible, and portable neuroimaging insight into canine cognitive processes. To promote systematization and create an overview of framings, methods and findings for future work, we provide a systematic review of non-invasive canine EEG studies (N=22), dissecting their study makeup, technical setup, and analysis frameworks and highlighting emerging trends. We further propose new directions of development, such as the standardization of data structures and integrating predictive modeling with descriptive statistical approaches. Our review ends by underscoring the advances and advantages of EEG-based canine cognitive neuroscience and the potential for accessible canine neuroimaging to inform both fundamental sciences as well as practical applications for cognitive neuroscience, working dogs, and human-canine interactions.

Development, validity, and reliability of Neural Circuits Questionnaire (NCQ)

After a prolonged period of using the cortico-centric models of brain function, scientists developed a parallel perspective with an emphasis on all neural structures of the brain. Therefore, the present study aims to create a valid and reliable assessment based on the parallel perspective of brain function. First, a basic assessment was made. Then, a sample size of 183 participants was recruited from graduates and undergraduates at the Ferdowsi University of Mashhad over a 2-year period (2020 and 2021). The measures were the Neural Circuits Questionnaire (NCQ) and the Demographic Data Questionnaire. Data analyses were performed by using exploratory factor analysis. Using a receiver operating characteristic (ROC) curve, cutting points for the quality index of the questionnaire were calculated. The results showed that the questionnaire has a three-factor structure and a Cronbach's alpha of 0.617. Based on the ROC curve, the valid range for the quality index is 10.5-15.5. The cerebro-cerebellar index is higher for Ph.D. students than for students with lower degrees (F = 8.60, p = 0.001). In conclusion, it appears that the Neural Circuits Questionnaire is a valid and reliable questionnaire to assess cognitive function following the parallel perspective of brain function.

A revitalized biopsychosocial model: core theory, research paradigms, and clinical implications

The biopsychosocial model (BPSM) was proposed by George Engel in 1977 as an improvement to the biomedical model (BMM), to take account of psychological and social as well as biological factors relevant to health and disease. Since then the BPSM has had a mixed reputation, as the overarching framework for psychiatry, perhaps for medicine generally, while also being criticized for being theoretically and empirically vacuous. Over the past few decades, substantial evidence has accumulated supporting the BPSM but its theory remains less clear. The first part of this paper reviews recent well-known, general theories in the relevant sciences that can provide a theoretical framework of the model, constituting a revitalized BPSM capable of theorizing causal interactions within and between biological, psychological, and social domains. Fundamental concepts in this new framework include causation as regulation and dysfunction as dysregulation. Associated research paradigms are outlined in Part 2. Research in psychological therapies and social epidemiology are major examples of programs that have produced results anomalous for the BMM and consistent with the BPSM. Theorized models of causal mechanisms enrich empirical data and two biopsychosocial examples are models of chronic stress and pain perception. Clinical implications are reviewed in Part 3. The BPSM accommodates psychological and social as well as biological treatment effects evident in the clinical trials literature. Personal, interpersonal, and institutional aspects of clinical care are out of the scope of the BMM, assigned to the art of healthcare rather than the science, but can be accommodated and theorized in the BPSM.

The Ecological View of Selective Attention

Accumulating evidence is supporting the hypothesis that our selective attention is a manifestation of mechanisms that evolved early in evolution and are shared by many organisms from different taxa. This surge of new data calls for the re-examination of our notions about attention, which have been dominated mostly by human psychology. Here, we present an hypothesis that challenges, based on evolutionary grounds, a common view of attention as a means to manage limited brain resources. We begin by arguing that evolutionary considerations do not favor the basic proposition of the limited brain resources view of attention, namely, that the capacity of the sensory organs to provide information exceeds the capacity of the brain to process this information. Moreover, physiological studies in animals and humans show that mechanisms of selective attention are highly demanding of brain resources, making it paradoxical to see attention as a means to release brain resources. Next, we build on the above arguments to address the question why attention evolved in evolution. We hypothesize that, to a certain extent, limiting sensory processing is adaptive irrespective of brain capacity. We call this hypothesis the ecological view of attention (EVA) because it is centered on interactions of an animal with its environment rather than on internal brain resources. In its essence is the notion that inherently noisy and degraded sensory inputs serve the animal's adaptive, dynamic interactions with its environment. Attention primarily functions to resolve behavioral conflicts and false distractions. Hence, we evolved to focus on a particular target at the expense of others, not because of internal limitations, but to ensure that behavior is properly oriented and committed to its goals. Here, we expand on this notion and review evidence supporting it. We show how common results in human psychophysics and physiology can be reconciled with an EVA and discuss possible implications of the notion for interpreting current results and guiding future research.

A Century of Brain Regeneration Phenomena and Neuromorphological Research Advances, 1890s-1990s-Examining the Practical Implications of Theory Dynamics in Modern Biomedicine

The modern thesis regarding the "structural plastic" properties of the brain, as reactions to injuries, to tissue damage, and to degenerative cell apoptosis, can hardly be seen as expendable in clinical neurology and its allied disciplines (including internal medicine, psychiatry, neurosurgery, radiology, etc.). It extends for instance to wider research areas of clinical physiology and neuropsychology which almost one hundred years ago had been described as a critically important area for the brain sciences and psychology alike. Yet the mounting evidence concerning the range of structural neuroplastic phenomena beyond the significant early 3 years of childhood has shown that there is a progressive building up and refining of neural circuits in adaptation to the surrounding environment. This review essay explores the history behind multiple biological phenomena that were studied and became theoretically connected with the thesis of brain regeneration from Santiago Ramón y Cajal's pioneering work since the 1890s to the beginning of the American "Decade of the Brain" in the 1990s. It particularly analyzes the neuroanatomical perspectives on the adaptive capacities of the Central Nervous System (CNS) as well as model-like phenomena in the Peripheral Nervous System (PNS), which were seen as displaying major central regenerative processes. Structural plastic phenomena have assumed large implications for the burgeoning field of regenerative or restorative medicine, while they also pose significant epistemological challenges for related experimental and theoretical research endeavors. Hereafter, early historical research precursors are examined, which investigated brain regeneration phenomena in non-vertebrates at the beginning of the 20th century, such as in light microscopic studies and later in electron microscopic findings that substantiated the presence of structural neuroplastic phenomena in higher cortical substrates. Furthermore, Experimental physiological research in hippocampal in vivo models of regeneration further confirmed and corroborated clinical physiological views, according to which "structural plasticity" could be interpreted as a positive regenerative CNS response to brain damage and degeneration. Yet the underlying neuroanatomical mechanisms remained to be established and the respective pathway effects were only conveyed through the discovery of neural stem cells in in adult mammalian brains in the early 1990s. Experimental results have since emphasized the genuine existence of adult neurogenesis phenomena in the CNS. The focus in this essay will be laid here on questions of the structure and function of scientific concepts, the development of research schools among biomedical investigators, as well as the impact of new data and phenomena through innovative methodologies and laboratory instruments in the neuroscientific endeavors of the 20th century.

One, no-one and a hundred thousand brains: J.C. Eccles, J.Z. Young and the establishment of the neurosciences (1930s-1960s)

Contemporary neurosciences have grown beyond the limits of a natural science. To its most vocal advocates, the study of the human brain can provide nothing short of the basis for a new science of man-the link between the "natural" and "human" sciences-as a simple consequence of the growing mass of facts relating to this most marvelous organ, accumulated in the last four decades. This straightforward picture of the growing import of the neurosciences simplifies and obscures the myriad different interpretations and images of "the brain" that have inspired the development of the neurosciences. Among them, this chapter will consider two deeply contrasting early images of the brain: the cellular-physiological brain proposed since the 1950s by John Carew Eccles, and the model-"whole" brain championed by John Zachary Young. Eccles' program was focused on the vertebrate synapse, and Young's on the whole brain of an "advanced" invertebrate (the octopus). The former was the programmatic extension of a long neurophysiological tradition, and the latter an outspoken attempt at providing a revolutionary model for the organization of an unprecedented research effort. One underscored continuity and scientific "soundness," and the other promised rupture and new, imaginative solutions to age-old problems. Nevertheless, they have been later lumped together into a single, marvelous and progressive history, or mythology, of the Science of the Brain. This chapter will show how the organizing principle of these two opposed (if almost equally successful) research efforts was not the foggy, ever-changing image of an experimental brain-in-becoming, but the clear, fixed horizon of a promised brain.

The association between social stress and global cognitive function in a population-based study: the European Prospective Investigation into Cancer (EPIC)-Norfolk study

BACKGROUND

Stress is thought to exert both positive and negative effects on cognition, but the precise cognitive effects of social stress and individuals' response to stress remain unclear. We aimed to investigate the association between different measures of social stress and cognitive function in a middle- to older-aged population using data from the European Prospective Investigation into Cancer (EPIC)-Norfolk study.

METHOD

Participants completed a comprehensive assessment of lifetime social adversity between 1993 and 1997 and the short form of the Mini Mental State Examination (SF-MMSE), an assessment of global cognitive function, during the third health check between 2004 and 2011 (a median of 10.5 years later). A low MMSE score was defined as a score in the bottom quartile (20-26).

RESULTS

Completed MMSE scores and stress measures were available for 5129 participants aged 48-90 years. Participants who reported that their lives had been more stressful over the previous 10 years were significantly more likely to have low MMSE scores [odds ratio (OR) 1.14, 95% confidence interval (CI) 1.04-1.24 per unit increase in perceived stress], independently of sociodemographic factors, physical and emotional health. The effects were restricted to the highest level of stress and the association was stronger among participants with a lower educational level. Adaptation following life event experiences also seemed to be associated with MMSE scores after adjusting for sociodemographic factors, but the association was attenuated with further adjustment.

CONCLUSIONS

In this generally high-functioning population, individuals' interpretations and responses to stressful events, rather than the events themselves, were associated with cognitive function.

Temporal and regional regulation of gene expression by calcium-stimulated adenylyl cyclase activity during fear memory

Background

The Ca2+-stimulated adenylyl cyclases (ACs), AC1 and AC8, are key components of long-term memory processing. AC1 and AC8 double knockout mice (Adcy1^−/−Adcy8^−/−; DKO) display impaired fear memory processing; the mechanism of this impairment is largely unknown.

Methodology/Principal Findings

We hypothesize that the Ca2+-stimulated ACs modulate long-lasting transcriptional changes essential for fear memory consolidation and maintenance. Here, we report a genome-wide study of gene expression changes associated with conditioned fear (CF) memory in wild-type and DKO mice to identify AC-dependent gene regulatory changes that occur in the amygdala and hippocampus at baseline and different time points after CF learning. We observed an overall decrease in transcriptional changes in DKO mice across all time points, but most strikingly, at periods when memory consolidation and retention should be occurring. Further, we identified a shared set of transcription factor binding sites in genes upregulated in wild-type mice that were associated with downregulated genes in DKO mice. To prove the temporal and regional importance of AC activity on different stages of memory processing, the tetracycline-off system was used to produce mice with forebrain-specific inducible expression of AC8 on a DKO background. CF behavioral results reveal that adult restoration of AC8 activity in the forebrain is sufficient for intact learning, while cessation of this expression at any time point across learning causes memory deficits.

Conclusions/Significance

Overall, these studies demonstrate that the Ca2+-stimulated ACs contribute to the formation and maintenance of fear memory by a network of long-term transcriptional changes.

Neural mechanisms for interacting with a world full of action choices

The neural bases of behavior are often discussed in terms of perceptual, cognitive, and motor stages, defined within an information processing framework that was originally inspired by models of human abstract problem solving. Here, we review a growing body of neurophysiological data that is difficult to reconcile with this influential theoretical perspective. As an alternative foundation for interpreting neural data, we consider frameworks borrowed from ethology, which emphasize the kinds of real-time interactive behaviors that animals have engaged in for millions of years. In particular, we discuss an ethologically-inspired view of interactive behavior as simultaneous processes that specify potential motor actions and select between them. We review how recent neurophysiological data from diverse cortical and subcortical regions appear more compatible with this parallel view than with the classical view of serial information processing stages.

Foundations of neuroeconomics: from philosophy to practice

How can we use neuroscience to better understand economic behavior? By quelling concerns about the nascent field of neuroeconomics, the authors defend future integrations of the biological and social sciences.

A computational model for feature binding

The "Binding Problem" is an important problem across many disciplines, including psychology, neuroscience, computational modeling, and even philosophy. In this work, we proposed a novel computational model, Bayesian Linking Field Model, for feature binding in visual perception, by combining the idea of noisy neuron model, Bayesian method, Linking Field Network and competitive mechanism. Simulation Experiments demonstrated that our model perfectly fulfilled the task of feature binding in visual perception and provided us some enlightening idea for future research.

A parallel framework for interactive behavior

Although theoretical models often assume that the basic organization of the nervous system involves separate systems for perception, cognition, and action, neural data often does not fit into any of these conceptual categories. Here, an alternative framework is described, which focuses on interactive behavior and treats it as a continuous competition between representations of currently available potential actions. This suggests a neural organization consisting of two parallel systems: a system for action specification, which uses sensory information to represent currently available potential actions, and a system for action selection, which involves attentional and decisional mechanisms which determine the action that will be performed. It is proposed that neural processing occurs through two waves of activation: an early wave which specifies several potential actions and a later wave of biasing influences which selects one action for execution. A computational model of decision making is described within the context of this proposal, and simulations of neural and behavioral phenomena are presented.

Promnesic effects of Ptychopetalum olacoides in aversive and non-aversive learning paradigms

Homemade remedies with Ptychopetalum olacoides (PO) roots are used by Amazonian peoples for treating various age-related conditions. We previously reported that Ptychopetalum olacoides ethanol extract significantly improved step-down inhibitory avoidance long-term memory in adult and reversed memory deficits in aging mice. Adding to previous data, this study shows that a single i.p. administration of Ptychopetalum olacoides ethanol extract (POEE 50 and 100 mg/kg) improved step-down inhibitory avoidance short-term memory (STM) 3 h after training in adult (2.5 month) mice; comparable results were obtained with POEE given p.o. at 800 mg/kg. Moreover, memory improvement was also observed in aging (14 months) mice presenting memory deficit as compared to adult mice. Furthermore, POEE (100 mg/kg) improved non-aversive memory systems in adult mice in an object recognition paradigm. Consistently with its traditional use this study add to previously reported data and reinforces that POEE facilitates memory processes. Although the acetylcholinesterase inhibitory properties described for this extract may be of relevance for improving memory processes, the molecular mechanism(s) underlying the memory improvement here reported needs further scrutiny.

Classification of adolescent psychotic disorders using linear discriminant analysis

BACKGROUND

The differential diagnosis between schizophrenia and bipolar disorder during adolescence presents a major clinical problem. Can these two diagnoses be differentiated objectively early in the courses of illness?

METHODS

We used linear discrimination analysis (LDA) to classify 28 adolescent subjects into one of three diagnostic categories (healthy, N=8; schizophrenia, N=10; bipolar, N=10) using subsets from a pool of 45 variables as potential predictors (22 neuropsychological test scores and 23 quantitative structural brain measurements). The predictor variables were adjusted for age, gender, race, and psychotropic medication. All possible subsets composed of k=2-12 variables, from the set of 45 variables available, were evaluated using the robust leaving-one-subject-out method.

RESULTS

The highest correct classification (96%) of the 3 diagnostic categories was yielded by 9 sets of k=12 predictors, comprising both neuropsychological and brain structural measures. Although each one of these sets misclassified one case, each set correctly classified (100%) at least one group, such that a fully correct diagnosis could be reached by a tree-type decision procedure.

CONCLUSIONS

We conclude that LDA with 12 predictor variables can provide correct and robust classification of subjects into the three diagnostic categories above. This robust classification relies upon both neuropsychological and brain structural information. Our results demonstrate that, despite overlapping clinical symptoms, schizophrenia and bipolar disorder can be differentiated early in the course of disease. This finding has two important implications. Firstly, schizophrenia and bipolar disorder are different illnesses. If schizophrenia and bipolar are dissimilar clinical manifestations of the same disease, we would not be able to use non-clinical information to classify ('diagnose') schizophrenia and bipolar disorder. Secondly, if this study's findings are replicated, brain structure (MRI) and brain function (neuropsychological) used together may be useful in the diagnosis of new patients.

Neuregulin-1 reverses long-term potentiation at CA1 hippocampal synapses

Neuregulin-1 (NRG-1) has been identified genetically as a schizophrenia susceptibility gene, but its function in the adult brain is unknown. Here, we show that NRG-1beta does not affect basal synaptic transmission but reverses long-term potentiation (LTP) at hippocampal Schaffer collateral-->CA1 synapses in an activity- and time-dependent manner. Depotentiation by NRG-1beta is blocked by two structurally distinct and selective ErbB receptor tyrosine kinase inhibitors. Moreover, ErbB receptor inhibition increases LTP at potentiated synapses and blocks LTP reversal by theta-pulse stimuli. NRG-1beta selectively reduces AMPA, not NMDA, receptor EPSCs and has no effect on paired-pulse facilitation ratios. Live imaging of hippocampal neurons transfected with receptors fused to superecliptic green fluorescent protein, as well as quantitative analysis of native receptors, show that NRG-1beta stimulates the internalization of surface glutamate receptor 1-containing AMPA receptors. This novel regulation of LTP by NRG-1 has important implications for the modulation of synaptic homeostasis and schizophrenia.

Precognitive and cognitive elements in sound localization

Sound localization behavior is of great importance for an animal's survival. To localize a sound, animals have to detect a sound source and assign a location to it. In this review we discuss recent results on the underlying mechanisms and on modulatory influences in the barn owl, an auditory specialist with very well developed capabilities to localize sound. Information processing in the barn owl auditory pathway underlying the computations of detection and localization is well understood. This analysis of the sensory information primarily determines the following orienting behavior towards the sound source. However, orienting behavior may be modulated by cognitive (top-down) influences such as attention. We show how advanced stimulation techniques can be used to determine the importance of different cues for sound localization in quasi-realistic stimulation situations, how attentional influences can improve the response to behaviorally relevant stimuli, and how attention can modulate related neural responses. Taken together, these data indicate how sound localization might function in the usually complex natural environment.

Procedural memory in Korsakoff's disease under different movement feedback conditions

Within the field of cognitive neuroscience, it has become widely accepted to distinguish between declarative and nondeclarative memory, with different neurobiological substrates subserving these memory structures. This distinction has been inferred from the study of amnesic patients, including those suffering from Korsakoff's syndrome. It is commonly agreed that Korsakoff patients demonstrate intact memory for motor and perceptual skills (nondeclarative) whereas memory of various forms of factual knowledge (declarative) is severely impaired. In the present study, Korsakoff patients and a group of age-matched controls learned a new bimanual motor skill whereby performance was assessed in the presence and absence of augmented visual information feedback. Findings demonstrated that Korsakoff patients were able to learn and retain this skill when directive augmented information feedback was provided while no learning occurred at all in the absence of this information. These observations shed new light on the conditions required for preserved memory in amnesic patients and challenge the classic view that nondeclarative memory is invariably preserved. Instead, the quality of memory across both motor and cognitive dimensions appears to depend on the availability of task-specific information to guide performance, presumably allowing amnesic patients to bypass affected brain areas. This prompts for a reevaluation of current notions about procedural memory capacity in Korsakoff patients.

Cyclic AMP-dependent protein kinase phosphorylates merlin at serine 518 independently of p21-activated kinase and promotes merlin-ezrin heterodimerization

Mutations in the NF2 tumor suppressor gene encoding merlin induce the development of tumors of the nervous system. Merlin is highly homologous to the ERM (ezrin-radixin-moesin) family of membrane/cytoskeleton linker proteins. However, the mechanism for the tumor suppressing activity of merlin is not well understood. Previously, we characterized a novel role for merlin as a protein kinase A (PKA)-anchoring protein, which links merlin to the cAMP/PKA signaling pathway. In this study we show that merlin is also a target for PKA-induced phosphorylation. In vitro [gamma-(33)P]ATP labeling revealed that both the merlin N and C termini are phosphorylated by PKA. Furthermore, both in vitro and in vivo phosphorylation studies of the wild-type and mutated C termini demonstrated that PKA can phosphorylate merlin at serine 518, a site that is phosphorylated also by p21-activated kinases (PAKs). Merlin was phosphorylated by PKA in cells in which PAK activity was suppressed, indicating that the two kinases function independently. Both in vitro and in vivo interaction studies indicated that phosphorylation of serine 518 promotes heterodimerization between merlin and ezrin, an event suggested to convert merlin from a growth-suppressive to a growth-permissive state. This study provides further evidence on the connection between merlin and cAMP/PKA signaling and suggests a role for merlin in the cAMP/PKA transduction pathway.

Possible role of intramembrane receptor-receptor interactions in memory and learning via formation of long-lived heteromeric complexes: focus on motor learning in the basal ganglia

Learning in neuronal networks occurs by instructions to the neurons to change their synaptic weights (i.e., efficacies). According to the present model a molecular mechanism that can contribute to change synaptic weights may be represented by multiple interactions between membrane receptors forming aggregates (receptor mosaics) via oligomerization at both pre- and post-synaptic level. These assemblies of receptors together with inter alia single receptors, adapter proteins, G-proteins and ion channels form the membrane bound part of a complex three-dimensional (3D) molecular circuit, the cytoplasmic part of which consists especially of protein kinases, protein phosphatases and phosphoproteins. It is suggested that this molecular circuit has the capability to learn and store information. Thus, engram formation will depend on the resetting of 3D molecular circuits via the formation of new receptor mosaics capable of addressing the transduction of the chemical messages impinging on the cell membrane to certain sets of G-proteins. Short-term memory occurs by a transient stabilization of the receptor mosaics producing the appropriate change in the synaptic weight. Engram consolidation (long-term memory) may involve intracellular signals that translocate to the nucleus to cause the activation of immediate early genes and subsequent formation of postulated adapter proteins which stabilize the receptor mosaics with the formation of long-lived heteromeric receptor complexes. The receptor mosaic hypothesis of the engram formation has been formulated in agreement with the Hebbian rule and gives a novel molecular basis for it by postulating that the pre-synaptic activity change in transmitter and modulator release reorganizes the receptor mosaics at post-synaptic level and subsequently at pre-synaptic level with the formation of novel 3D molecular circuits leading to a different integration of chemical signals impinging on pre- and post-synaptic membranes hence leading to a new value of the synaptic weight. Engram retrieval is brought about by the scanning of the target networks by the highly divergent arousal systems. Hence, a continuous reverberating process occurs both at the level of the neural networks as well as at the level of the 3D molecular circuits within each neuron of the network until the appropriate tuning of the synaptic weights is obtained and, subsequently, the reappearance of the engram occurs. Learning and memory in the basal ganglia is discussed in the frame of the present hypothesis. It is proposed that formation of long-term memories (consolidated receptor mosaics) in the plasma membranes of the striosomal GABA neurons may play a major role in the motivational learning of motor skills of relevance for survival. In conclusion, long-lived heteromeric receptor complexes of high order may be crucial for learning, memory and retrieval processes, where extensive reciprocal feedback loops give rise to coherent synchronized neural activity (binding) essential for a sophisticated information handling by the central nervous system.

Separation-induced receptor changes in the hippocampus and amygdala of Octodon degus: influence of maternal vocalizations

Relatively little is known about the basic mechanisms that play a role in the vulnerability of the developing brain toward adverse environmental influences. Our study in the South American rodent Octodon degus revealed that repeated brief separation from the parents and exposure to an unfamiliar environment induces in the hippocampal formation of male and female pups an upregulation of D1 and 5-HT1A receptor density in the stratum radiatum and stratum lacunosum moleculare of the CA1 region. In the CA3 region, only the 5-HT1A receptors were upregulated; no changes were observed for D1 receptors in this region. GABA(A) receptor density in the hippocampus and amygdala was downregulated (nonsignificant trend) after parental separation. The acoustic presence of the mother during parental separation suppressed the D1 and 5-HT1A receptor upregulation in some regions of the hippocampus; no such suppressing influence was observed for the GABA(A) receptors. In the basomedial amygdala, the maternal calls enhanced the separation-induced 5-HT1A receptor upregulation in the male pups, whereas in the female pups the separation-induced receptor densities were not only suppressed by the maternal call but further downregulated, compared with the control group. These results demonstrate that early adverse emotional experience alters aminergic function within the hippocampus and amygdala and that the mother's voice, a powerful emotional signal, can modulate these effects in the developing limbic system.

Mother's voice "buffers" separation-induced receptor changes in the prefrontal cortex of octodon degus

Although the potential vulnerability of the postnatally developing brain toward adverse environmental influences is generally recognized, relatively little is known about the basic mechanisms involved. The plasticity and adaptability of the postnatally developing brain in response to adverse emotional experiences was analyzed in the South American Octodon degus. Our study revealed that repeated brief separation from the parents and exposure to an unfamiliar environment induces an up-regulation of dopamine (D1) and 5-hydroxytrytamine (5HT1(A))-receptor density in the precentral medial, anterior cingulate, prelimbic and infralimbic cortices in female pups. No significant changes of gamma aminobutyric acid (GABA(A)) receptor density were found in deprived animals of both genders. The acoustic presence of the mother during parental separation suppressed the D1-receptor up-regulation as well as the 5-HT1(A)-receptor up-regulation, again only in the female pups. These results demonstrate that that early adverse emotional experience alters aminergic function within the prefrontal cortex in the female but not the male brain. The mother's voice, a powerful emotional signal, can protect the developing cortex from separation-induced receptor changes.

Hippocampal gene expression profiling in spatial discrimination learning

Learning and long-term memory are thought to involve temporally defined changes in gene expression that lead to the strengthening of synaptic connections in selected brain regions. We used cDNA microarrays to study hippocampal gene expression in animals trained in a spatial discrimination-learning paradigm. Our analysis identified 19 genes that showed statistically significant changes in expression when comparing Nai;ve versus Trained animals. We confirmed the changes in expression for the genes encoding the nuclear protein prothymosin(alpha) and the delta-1 opioid receptor (DOR1) by Northern blotting or in situ hybridization. In additional studies, laser-capture microdissection (LCM) allowed us to obtain enriched neuronal populations from the dentate gyrus, CA1, and CA3 subregions of the hippocampus from Nai;ve, Pseudotrained, and spatially Trained animals. Real-time PCR examined the spatial learning specificity of hippocampal modulation of the genes encoding protein kinase B (PKB, also known as Akt), protein kinase C(delta) (PKC(delta)), cell adhesion kinase(beta) (CAK(beta), also known as Pyk2), and receptor protein tyrosine phosphatase(zeta/beta) (RPTP(zeta/beta)). These studies showed subregion specificity of spatial learning-induced changes in gene expression within the hippocampus, a feature that was particular to each gene studied. We suggest that statistically valid gene expression profiles generated with cDNA microarrays may provide important insights as to the cellular and molecular events subserving learning and memory processes in the brain.

Cholinergic neurotransmission is essential for perirhinal cortical plasticity and recognition memory

We establish the importance of cholinergic neurotransmission to both recognition memory and plasticity within the perirhinal cortex of the temporal lobe. The muscarinic receptor antagonist scopolamine impaired the preferential exploration of novel over familiar objects, disrupted the normal reduced activation of perirhinal neurones to familiar compared to novel pictures, and blocked production of long-term depression (LTD) but not long-term potentiation (LTP) of synaptic transmission in perirhinal slices. The consistency of these effects across the behavioral, systems, and cellular levels of analysis provides strong evidence for the involvement of cholinergic mechanisms in synaptic plastic processes within perirhinal cortex that are necessary for recognition memory.

Experience-dependent expression of terminal deoxynucleotidyl transferase in mouse brain

Terminal deoxynucleotidyl transferase (TdT), a template-independent DNA polymerase, contributes to antigen receptor diversity in lymphocytes. Using in situ hybridization, we found that tdt is expressed within neurons of the adult mouse brain. tdt mRNA was localized within pyramidal neurons in the hippocampus, granule and polymorphic cells in the dentate gyrus, Purkinje neurons in the cerebellum, and cortical cells. Increased levels of tdt mRNA in the hippocampus, neocortex, and cerebellum were associated with rearing C57BL/6 mice, but not DBA/2 mice, in enriched environments. Unlike wild types (WT), tdt (-/-) mice did not show improvement in spatial learning and memory as a result of rearing in enriched environments. These results suggest that tdt may be involved in learning and memory saving.

The emerging dialogue between psychoanalysis and neuroscience: neuroimaging perspectives

Current progress in the cognitive neurosciences is highly relevant to the development of psychoanalytic theory and practice. Neuroscience is today becoming mature enough to provide empirical biological approaches for the investigation of psychoanalytic models and observations. The current state of functional neuroimaging techniques is reviewed, selected paradigms and findings relevant to psychotherapy research are presented, and ways to pursue the dialogue between psychoanalysts and neuroscientists are discussed, as are some related obstacles and pitfalls. The emerging dialogue between psychoanalysts and neuroscientists may help not only to reestablish a solid position of psychodynamic theory and treatment in contemporary medicine, but also to bridge the division between "psychological" and "somatic" treatments, and gain important insights into the mind-brain relationship.

How do cyanobacteria sense and respond to light?

Cyanobacteria exhibit numerous responses to changes in the intensity and spectral quality of light. What sensors do cyanobacteria use to detect light and what are the mechanisms of signal transduction? The publication in 1996 of the complete genome sequence of the cyanobacterium Synechocystis 6803 provided a tremendous stimulus for research in this field, and many light-sensors and signal transducers have now been identified. However, our knowledge of cyanobacterial light-signal transduction remains fragmentary. This review summarizes what we know about the ways in which cyanobacteria perceive light, some of the ways which they respond to light signals and some recent achievements in elucidating the signal transduction mechanisms. Some problems in characterizing cyanobacterial signal transduction pathways are outlined and alternative experimental strategies are discussed.