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Near-infrared spectroscopy (NIRS) in cognitive neuroscience of the primate brain.

We describe the use of near-infrared spectroscopy (NIRS) as a suitable means of assessing hemodynamic changes in the cerebral cortex of awake and behaving monkeys. NIRS can be applied to animals performing cognitive tasks in conjunction with electrophysiological methods, thus offering the possibility of investigating cortical neurovascular coupling in cognition. Because it imposes fewer constraints on behavior than fMRI, NIRS appears more practical than fMRI for certain studies of cognitive neuroscience on the primate cortex. In the present study, NIRS and field potential signals were simultaneously recorded from the association cortex (posterior parietal and prefrontal) of monkeys performing two delay tasks, one spatial and the other non-spatial. Working memory was accompanied by an increase in oxygenated hemoglobin mirrored by a decrease in deoxygenated hemoglobin. Both the trends and the amplitudes of these changes differed by task and by area. Field potential records revealed slow negative potentials that preceded the task trials and persisted during their memory period. The negativity during that period was greater in prefrontal than in parietal cortex. Between tasks, the potential differences were less pronounced than the hemodynamic differences. The present feasibility study lays the groundwork for future correlative studies of cognitive function and neurovascular coupling in the primate.

Algorithms↗

The semantics of space: integrating linguistic typology and cognitive neuroscience.

In the cognitive neuroscience literature on the distinction between categorical and coordinate spatial relations, it has often been observed that categorical spatial relations are referred to linguistically by words like English prepositions, many of which specify binary oppositions-e.g., above/below, left/right, on/off, in/out. However, the actual semantic content of English prepositions, and of comparable word classes in other languages, has not been carefully considered. This paper has three aims. The first and most important aim is to inform cognitive neuroscientists interested in spatial representation about relevant research on the kinds of categorical spatial relations that are encoded in the 6000+ languages of the world. Emphasis is placed on cross-linguistic similarities and differences involving deictic relations, topological relations, and projective relations, the last of which are organized around three distinct frames of reference--intrinsic, relative, and absolute. The second aim is to review what is currently known about the neuroanatomical correlates of linguistically encoded categorical spatial relations, with special focus on the left supramarginal and angular gyri, and to suggest ways in which cross-linguistic data can help guide future research in this area of inquiry. The third aim is to explore the interface between language and other mental systems, specifically by summarizing studies which suggest that although linguistic and perceptual/cognitive representations of space are at least partially distinct, language nevertheless has the power to bring about not only modifications of perceptual sensitivities but also adjustments of cognitive styles.

Cognition↗

A cognitive neuroscience perspective on psychopathy: evidence for paralimbic system dysfunction.

Psychopathy is a complex personality disorder that includes interpersonal and affective traits such as glibness, lack of empathy, guilt or remorse, shallow affect, and irresponsibility, and behavioral characteristics such as impulsivity, poor behavioral control, and promiscuity. Much is known about the assessment of psychopathy; however, relatively little is understood about the relevant brain disturbances. The present review integrates data from studies of behavioral and cognitive changes associated with focal brain lesions or insults and results from psychophysiology, cognitive psychology and cognitive and affective neuroscience in health and psychopathy. The review illustrates that the brain regions implicated in psychopathy include the orbital frontal cortex, insula, anterior and posterior cingulate, amygdala, parahippocampal gyrus, and anterior superior temporal gyrus. The relevant functional neuroanatomy of psychopathy thus includes limbic and paralimbic structures that may be collectively termed 'the paralimbic system'. The paralimbic system dysfunction model of psychopathy is discussed as it relates to the extant literature on psychopathy.

Affect↗

Shared representations between self and other: a social cognitive neuroscience view.

The abilities to identify with others and to distinguish between self and other play a pivotal role in intersubjective transactions. Here, we marshall evidence from developmental science, social psychology and neuroscience (including clinical neuropsychology) that support the view of a common representation network (both at the computational and neural levels) between self and other. However, sharedness does not mean identicality, otherwise representations of self and others would completely overlap, and lead to confusion. We argue that self-awareness and agency are integral components for navigating within these shared representations. We suggest that within this shared neural network the inferior parietal cortex and the prefrontal cortex in the right hemisphere play a special role in interpersonal awareness.

Journal Article↗

Social cognitive neuroscience: where are we heading?

Humans crave the company of others and suffer profoundly if temporarily isolated from society. Much of the brain must have evolved to deal with social communication and we are increasingly learning more about the neurophysiological basis of social cognition. Here, we explore some of the reasons why social cognitive neuroscience is captivating the interest of many researchers. We focus on its future, and what we believe are priority areas for further research.

Bayes Theorem↗

Imitation: is cognitive neuroscience solving the correspondence problem?

Imitation poses a unique problem: how does the imitator know what pattern of motor activation will make their action look like that of the model? Specialist theories suggest that this correspondence problem has a unique solution; there are functional and neurological mechanisms dedicated to controlling imitation. Generalist theories propose that the problem is solved by general mechanisms of associative learning and action control. Recent research in cognitive neuroscience, stimulated by the discovery of mirror neurons, supports generalist solutions. Imitation is based on the automatic activation of motor representations by movement observation. These externally triggered motor representations are then used to reproduce the observed behaviour. This imitative capacity depends on learned perceptual-motor links. Finally, mechanisms distinguishing self from other are implicated in the inhibition of imitative behaviour.

Animals↗

The neuroscience of tinnitus.

Tinnitus is an auditory phantom sensation (ringing of the ears) experienced when no external sound is present. Most but not all cases are associated with hearing loss induced by noise exposure or aging. Neuroscience research has begun to reveal how tinnitus is generated by the brain when hearing loss occurs, and to suggest new avenues for management and prevention of tinnitus following hearing injuries. Downregulation of intracortical inhibition induced by damage to the cochlea or to auditory projection pathways highlights neural processes that underlie the sensation of phantom sound.

Animals↗

The cognitive neuroscience of signed language.

The present article is an assessment of the current state of knowledge in the field of cognitive neuroscience of signed language. Reviewed lesion data show that the left hemisphere is dominant for perception and production of signed language in aphasics, in a fashion similar to spoken language aphasia. Several neuropsychological dissociations support this claim: Non-linguistic visuospatial functions can be dissociated from spatial functions and general motor deficits can be dissociated from execution of signs. Reviewed imaging data corroborate the lesion data in that the importance of the left hemisphere is re-confirmed. The data also establish the role of the right hemisphere in signed language processing. Alternative hypotheses regarding what aspects of signed language processing are handled by the right hemisphere are currently tested. The second section of the paper starts by addressing the role that early acquisition of signed and spoken language play for the neurofunctional activation patterns in the brain. Compensatory cognitive and communicative enhancements have also been documented as a function of early sign language use, suggesting an interesting interaction between language and cognition. Recent behavioural data on sign processing in working memory--a cognitive system important for language perception and production suggest e.g. phonological loop effects analogous to those obtained for speech processing. Neuroimaging studies will have to address this potential communality.

Functional Laterality↗

The relationship between remembering and knowing: a cognitive neuroscience perspective.

Cognitive neuroscience has provided strong support for the idea that there are multiple memory systems. Recent evidence suggests that remembering and knowing may be two types of recognition with different neural substrates. The remember/know distinction is not equivalent to the explicit/implicit distinction because both remembering and knowing are impaired after damage to medial temporal lobe structures. A number of converging lines of evidence suggest that the relationship between remembering and knowing is one redundancy, with "knowing" processes also active during remembering. Remembering appears to depend additionally on frontal lobe functioning.

Amnesia↗

Synchronous gamma activity: a review and contribution to an integrative neuroscience model of schizophrenia.

Synchronous high frequency (Gamma band) activity has been proposed as a candidate mechanism for the integration or 'binding' of distributed brain activities. Since the first descriptions of schizophrenia, attempts to characterize this disorder have focused on disturbances in such integrative processing. Here, we review both micro- and macroscopic neuroscience research into Gamma synchrony, and its application to understanding schizophrenia. The review encompasses evidence from both animal and human studies for the functional significance of Gamma activity, the association between Gamma dysfunction and information processing disturbances, and the relevance of specific Gamma dysfunctions to the integration and extension of previous disconnection models of schizophrenia. Attention is given to the relationship between Gamma activity and the heterogeneous symptoms of schizophrenia. Existing studies show that measures of Gamma activity have the potential to explain far more of the variance in schizophrenia performance than previous neurophysiological measures. It is concluded that measures of Gamma synchrony offer a valuable window into the core integrative disturbance in schizophrenia cognition.

Action Potentials↗

The neuroscience of depression in adolescence.

The neuroscience of depression in children and adolescents has only recently become a focus of research. Initially, techniques previously used for adult investigations were employed, such as endocrine studies and sleep studies. Endocrine studies have indicated that, as in adult depression, a dysregulation of the serotonin (5-HT) axis is involved in childhood depression. However, both of these techniques are difficult to perform in children and have yielded some inconsistent results. The more recently developed neuroimaging techniques should enable the greatest advances in our understanding of the pathophysiology of depression. These techniques have already implicated the frontal lobes in the pathogenesis of depression in children and adolescents, and further research is ongoing.

Adolescent↗

The neuroscience of drug addiction: Rome built in a day.

The Second Conference on the Neuroscience of Drug Addiction was a one-day meeting held in Rome, Italy at the Istituto Superiore di Sanità on 27 September 2002. Molecular, behavioral, pharmacological and clinical aspects of drug addiction were covered.

Animals↗

Affective neuroscience and the development of social anxiety disorder.

Recent studies on the familial distribution and longitudinal outcome of SAD emphasize developmental aspects of the syndrome, consistent with the developmental psychopathology perspective. Key questions in this area concern factors that mediate familial transmission and that predict outcome. Prior studies provide incomplete answers to these questions. Recent studies in affective neuroscience suggest potential avenues for answering these questions. As reviewed in the current article, fMRI studies of face processing provide examples of such potentially informative research directions.

Adult↗

The controls of eating: a shift from nutritional homeostasis to behavioral neuroscience.

The experimental analysis of the controls of eating has undergone a paradigmatic shift in the past decade. Instead of seeing meals as a problem of how intake serves metabolism and nutritional homeostasis, meals are now seen as a problem in behavioral neuroscience. The major developments underlying this significant change are behavioral, neurological, and theoretical. Behavioral analysis has shown that a central pattern generator in the caudal brainstem organizes eating movements and that the size of a liquid meal is determined by the number and size of clusters of licking. Neurologic analysis has shown that eating is under orosensory positive-feedback control and postingestive, preabsorptive, negative-feedback control. These feedback controls are activated by food ingested during a meal. The sensory information of the feedbacks is carried by afferent fibers that project to the caudal brainstem. The new theory is based on the fact that the feedback controls are stimulated by food acting directly on mucosal receptors along the gastrointestinal tract, from the mouth to the end of the small intestine. Thus, they are referred to as direct controls, and the caudal brainstem is sufficient for organizing their action. All other controls, such as metabolic, rhythmic, and ecologic, that do not contact the mucosal receptors are indirect controls. Indirect controls act by modulating the potency of the central effects of the direct controls, and they require the forebrain and its reciprocal connections with the caudal brainstem for their control of eating and meal size.

Animals↗

Cognitive neuroscience.

The last decade of the 20th century has seen the development of cognitive neuroscience as an effort to understand how the brain represents mental events. We review the areas of emotional and motor memory, vision, and higher mental processes as examples of this new understanding. Progress in all of these areas has been swift and impressive, but much needs to be done to reveal the mechanisms of cognition at the local circuit and molecular levels. This work will require new methods for controlling gene expression in higher animals and in studying the interactions between neurons at multiple levels.

Animals↗

Cognitive neuroscience of attention deficit hyperactivity disorder and hyperkinetic disorder.

Currently, diagnoses of attention deficit hyperactivity disorder (ADHD) and hyperkinetic disorder (HKD) are made on the basis of phenomenology, but information is accumulating from the neurosciences about the biological bases of these disorders. Recent studies addressing the neuropsychology, neuroanatomy, neurochemistry, and molecular biology of ADHD/HKD document abnormalities in well-defined neuroanatomical networks and neurochemical pathways. Magnetic resonance imaging (MRI) studies have shown that some regions of the frontal lobes (anterior superior and inferior) and basal ganglia (caudate nucleus and globus pallidus) are about 10% smaller in ADHD groups than in control groups of children, and molecular genetic studies have shown that diagnosis of ADHD is associated with polymorphisms in some dopamine genes (the dopamine D4 receptor gene and the dopamine transporter gene).

Animals↗

When the self represents the other: a new cognitive neuroscience view on psychological identification.

There is converging evidence from developmental and cognitive psychology, as well as from neuroscience, to suggest that the self is both special and social, and that self-other interaction is the driving force behind self-development. We review experimental findings which demonstrate that human infants are motivated for social interactions and suggest that the development of an awareness of other minds is rooted in the implicit notion that others are like the self. We then marshall evidence from functional neuroimaging explorations of the neurophysiological substrate of shared representations between the self and others, using various ecological paradigms such as mentally representing one's own actions versus others' actions, watching the actions executed by others, imitating the others' actions versus being imitated by others. We suggest that within this shared neural network the inferior parietal cortex and the prefrontal cortex in the right hemisphere play a special role in the essential ability to distinguish the self from others, and in the way the self represents the other. Interestingly, the right hemisphere develops its functions earlier than the left.

Awareness↗

How similar are fluid cognition and general intelligence? A developmental neuroscience perspective on fluid cognition as an aspect of human cognitive ability.

This target article considers the relation of fluid cognitive functioning to general intelligence. A neurobiological model differentiating working memory/executive function cognitive processes of the prefrontal cortex from aspects of psychometrically defined general intelligence is presented. Work examining the rise in mean intelligence-test performance between normative cohorts, the neuropsychology and neuroscience of cognitive function in typically and atypically developing human populations, and stress, brain development, and corticolimbic connectivity in human and nonhuman animal models is reviewed and found to provide evidence of mechanisms through which early experience affects the development of an aspect of cognition closely related to, but distinct from, general intelligence. Particular emphasis is placed on the role of emotion in fluid cognition and on research indicating fluid cognitive deficits associated with early hippocampal pathology and with dysregulation of the hypothalamic-pituitary-adrenal axis stress-response system. Findings are seen to be consistent with the idea of an independent fluid cognitive construct and to assist with the interpretation of findings from the study of early compensatory education for children facing psychosocial adversity and from behavior genetic research on intelligence. It is concluded that ongoing development of neurobiologically grounded measures of fluid cognitive skills appropriate for young children will play a key role in understanding early mental development and the adaptive success to which it is related, particularly for young children facing social and economic disadvantage. Specifically, in the evaluation of the efficacy of compensatory education efforts such as Head Start and the readiness for school of children from diverse backgrounds, it is important to distinguish fluid cognition from psychometrically defined general intelligence.

Adolescent↗