Neuroscience and biobehavioral reviews
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Neurosci Biobehav Rev · Feb 2005
ReviewAnxiety and panic: from human studies to animal research and back.
The role of learning and conditioning varies across human anxiety disorders, and distinguishing between fear and panic is important to guide investigation in panic disorder. By reminding that some psychological and psychobiological theories view panic attacks as false alarms of unconditioned biological origin, we suggest that employing endophenotypes of biological and evolutionary relevance--such as the respiratory responses to suffocative stimuli--can be fruitful for both human research and animal models of panic, and can help keeping unconditioned components of the clinical picture separate from the conditioned components in the experimental setting. We present a review of a model of panic disorder by which idiosyncratic environmental adverse events can promote unconditioned and unexpected spells of physical alarm. ⋯ The overproduction of the Acetylcholinesterase readthrough splice variant after minor stress can promote passive avoidance and learning through action at the level of the corticolimbic circuitries, as well as heightened sensitivity to suffocative stimuli by action upon the cholinergic components of chemoception. When a component of anticipatory anxiety complicates the clinical picture of recurrent panic attacks, and the HPA becomes activated, the glucocorticoid response element 17 kb upstream of the Acetylcholinesterase gene transcription initiation site may sustain sensitivity to suffocative stimuli for prolonged time. Finally, we review how animal models of human panic based on unconditioned provocation of alarm reactions by the same respiratory panicogens that are employed in man are viable and promising.
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Neurosci Biobehav Rev · Feb 2005
ReviewSocial factors and individual vulnerability to chronic stress exposure.
The stress-response is adaptive in the short-term, but it can be maladaptive if sustained levels of its mediators are chronically maintained. Furthermore, not all individuals exposed to chronic stress will progress to disease. Thus, understanding the causes of individual differences and the consequences of variation in vulnerability is of major importance. ⋯ Behavior, autonomic and immune functions, hypothalamic-pituitary-adrenocortical responses, brain cytokine expression and cardiac histology were investigated in stress-exposed mice. Certain stress-induced alterations were present in all mice independent of their social status, while others clearly differentiated dominants from subordinates. RS mice showed a unique profile of alterations suggesting that the loss of relevant resources, such as the territory, is the key factor determining why only certain stress-exposed individuals ultimately show malignancy and psychopathologies.
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Neurosci Biobehav Rev · Jan 2005
Review Biography Historical ArticleDonald O. Hebb's synapse and learning rule: a history and commentary.
This year sees the anniversary of Donald O. Hebb's birth, in July 1904. ⋯ His core postulate, which gave rise to such eponymous expressions as the Hebbian synapse and the Hebbian learning rule, is examined in some detail, as well as the part it played in his higher-order theoretical constructs concerned with neocortical structure and function. Early models which made use of the Hebbian synapse are described, and then illustrative examples are given detailing the impact of Hebb's idea in relation to learning and memory, synaptic plasticity and stability, and the question of persistent cortical activity underlying forms of short-term memory.
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Neurosci Biobehav Rev · Jan 2005
Review Meta AnalysisMeta-analysis of sex differences in rodent models of learning and memory: a review of behavioral and biological data.
The existence of sex differences in the standard rat and mouse models of learning and memory is a controversial and contested topic in the literature. The present meta-analysis of radial maze and water maze experiments was conducted to assess the reliablility and magnitude of sex effects in the standard rodent models of learning and memory. Data were culled from published and unpublished sources. ⋯ Together these findings establish the reliability of male advantages in spatial working and reference memory for rats across strains, protocols, ages and rearing environments. The findings also support an important species dichotomy between rats and mice that should be considered when transitioning from rat to mouse models. In light of these results, the biological evidence supporting theoretical explanations of sex differences is reviewed and evaluated.
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Neurosci Biobehav Rev · Jan 2005
ReviewFunctional connectivity in the brain--is it an elusive concept?
Even though functional brain connectivity is an influential concept in modern cognitive neuroscience, it is a very controversial notion. This is why further theoretical and methodological clarification are needed to help define precisely what is meant by functional connectivity and to help frame-associated issues. ⋯ Here functional connectivity is the mechanism for the coordination of activity between different neural assemblies in order to achieve a complex cognitive task or perceptual process. Our theoretical and empirical findings offer new insights into possible implications of the concept of functional connectivity for cognitive neuroscience.