J Integr Neurosci
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The present review attempts to put together the available evidence and potential research paradigms at the interface of obstructive sleep apnea syndrome (OSAS), sleep micro- and macrostructure, cerebral vasoreactivity and cognitive neuroscience. Besides the significant health-related consequences of OSAS including hypertension, increased risk of cardio- and cerebrovascular events, notable neurocognitive lapses and excessive daytime somnolence are considered as potential burdens. The intermittent nocturnal hypoxia and hypercapnia which occur in OSAS are known to affect cerebral circulation and result in brain hypoperfusion. ⋯ This is proposed to be related to an upregulated proinflammatory state which may potentially result in apoptotic cell loss in the brain. On this basis, a pragmatic framework of the possible neural mechanisms which underpin obstructive sleep apnea-related neurocognitive decline has been discussed in this review. In addition, the impact of OSAS on cerebral autoregulation and sleep microstructure has been articulated.
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Human behavior emerges from a complex dynamic interaction between graded and context-sensitive neural processes, the biomechanics of our bodies, and the vicissitudes of our environments. These coupled processes bear little resemblance to the iterated application of simple symbolic rules. ⋯ A prototypical case is when succinct verbal instructions are communicated and are promptly followed by another. How does the brain support such rule-guided behavior? How are explicit rules represented in the brain? How are rule representations shaped by experience? What neural processes form the foundation of our ability to systematically represent and apply rules from the vast range of possible rules? This article reviews a line of research that has sought a computational cognitive neuroscience account of rule-guided behavior in terms of the functioning of the prefrontal cortex, the basal ganglia, and related brain systems.
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The term synaptic plasticity describes the ability of excitatory synapses to undergo activity-driven long-lasting changes in the efficacy of basal synaptic transmission. This change may be expressed as a long-term potentiation (LTP) or as a long-term depression (LTD). Metaplasticity is a higher-order form of synaptic plasticity that regulates the expression of both LTP and LTD through processes that are initiated by cellular activity that precedes a later bout of plasticity-inducing synaptic activity. ⋯ The intracellular mechanisms which support metaplasticity appear to be closely linked to those of synaptic plasticity, hence there are significant technical challenges to overcome in order to elucidate those mechanisms specific to metaplasticity. This review will examine the progress in the characterization of metaplasticity over the last decade or so with a focus on findings gained using electrophysiological techniques. It will look at the techniques applied, the brain regions investigated and the knowledge gained from the application of a wide range of protocols designed to examine the influence of varied forms of prior synaptic activity on later, activity-induced, synaptic plasticity.