Behavioral neuroscience
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Executive function allows us to interact with the world in a purposive, goal-directed manner. It relies on several cognitive control operations that are mediated by different regions of the prefrontal cortex. While much of our knowledge about the functional subdivisions of the prefrontal cortex comes from the systematic assessment of patients with brain damage, animal models have served as the predominant tool for investigating specific structure-function relationships within the prefrontal cortex, especially as they relate to complex executive behaviors. ⋯ The effects of lesions and local pharmacological manipulations have provided valuable insights into the neural underpinnings of executive function and its neurochemical modulation. Despite the challenges associated with establishing a precise homology between animal models of prefrontal function and the human brain, such models currently offer the best means to systematically investigate the cognitive building blocks of executive function. This helps define the neural circuits that lead to a range of neurological and psychiatric disorders and facilitate the development of effective therapeutic strategies to ameliorate the associated cognitive impairments.
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Behavioral neuroscience · Apr 2011
Comparative StudyProcessing of expected and unexpected monetary performance outcomes in healthy older subjects.
The feedback-related negativity (FRN), an event-related potential (ERP) component reflecting feedback processing in the anterior cingulate cortex (ACC), has consistently been found to be reduced in healthy aging, whereas behavioral findings regarding age-related changes in decision making and feedback-based learning are inconsistent. This study aimed to elucidate similarities and differences between healthy younger and older subjects in the processing of monetary performance feedback focusing on effects of reward expectancy. Eighteen younger and 20 older subjects completed a feedback learning task, in which a rule could be learned to predict the reward probabilities associated with particular stimuli. ⋯ Consistent with previous findings, the amplitude difference tended to be generally reduced in older subjects. P300 amplitude was larger for reward than nonreward in both groups, and interactions between valence and probability indicated that only the P300 for reward was modulated by expectancy. Despite general changes of outcome-related ERPs in healthy aging, older subjects show evidence of preserved effects of expectancy on the processing of monetary feedback.
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Behavioral neuroscience · Feb 2011
Comparative StudyRapid cellular genesis and apoptosis: effects of exercise in the adult rat.
Long-term aerobic exercise improves cognition in both human and nonhuman animals and induces plastic changes in the central nervous system (CNS), including neurogenesis and angiogenesis. However, the early and immediate effects of exercise on the CNS have not been adequately explored. There is some evidence to suggest that exercise is initially challenging to the nervous system and that the plastic changes commonly associated with chronic exercise may result as adaptations to this challenge. ⋯ The temporal pattern of these events suggests that voluntary exercise in the adult rat rapidly and transiently induces apoptosis, followed by angiogenesis. Neurogenesis is an immediate and independent consequence of exercise in the hippocampus that may require the additional metabolic support supplied by angiogenesis. This is the first report of CNS neuronal apoptosis as a consequence of exercise in the adult rat and suggests that this process is a potential mediator of rapid exercise-induced plasticity.
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Behavioral neuroscience · Feb 2010
Amygdala-dependent fear conditioning in humans is modulated by the BDNFval66met polymorphism.
The brain-derived neurotrophic factor (BDNF) is critically involved in neuroplasticity, as well as the acquisition, consolidation, and retention of hippocampal- and amygdala-dependent learning. A common functional A-->G single nucleotide polymorphism (BDNFval66met) in the prodomain of the human BDNF gene is associated with abnormal intracellular trafficking and reduced activity-dependent BDNF release. We studied the effect of BDNFval66met in an aversive differential fear conditioning, and a delayed extinction paradigm in 57 healthy participants. ⋯ No genotype differences were found in conditioned SCR discrimination. These data provide evidence for the involvement of BDNF signaling in human amygdala-dependent learning. We suggest that the BDNF met-allele may have a protective effect for the development of affective pathologies that may be mediated via reduced synaptic plasticity induced by negative experience.
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Behavioral neuroscience · Oct 2009
Cold pressor stress impairs performance on working memory tasks requiring executive functions in healthy young men.
The current study investigated the effects of cold pressor stress (CPS) on 2 working memory (WM) tasks differing in the demand they put on maintenance and executive processing. For this purpose 72 healthy young men were exposed either to a stress group or a nonstressful control group. Subsequently, WM performance on the O-Span task (Turner & Engle, 1989) and the digit span task was assessed. ⋯ Results revealed a significant performance impairment of the O-Span and the digit span task backward in stressed subjects that correlated negatively with CPS-induced cortisol increases. Digit span forward was neither affected by CPS nor related to the ensuing cortisol increases. These results indicate that acute stress impairs WM performance for tasks requiring executive functions that operate on the stored material but not for WM tasks that only require maintenance.