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System Underlying (system + underlying)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

A Microdialysis Profile of Dynorphin A1,8 Release in the Rat Nucleus Accumbens Following Alcohol Administration

ALCOHOLISM, Issue 6 2006
Peter W. Marinelli
Background: Pharmacological studies have implicated the endogenous opioid system in mediating alcohol intake. Other evidence has shown that alcohol administration can influence endorphinergic and enkephalinergic activity, while very few studies have examined its effect on dynorphinergic systems. The aim of the present study was to investigate the effect of alcohol administration or a mechanical stressor on extracellular levels of dynorphin A1,8 in the rat nucleus accumbens,a brain region that plays a significant role in the processes underlying reinforcement and stress. Methods: Male Sprague,Dawley rats were implanted with a microdialysis probe aimed at the shell region of the nucleus accumbens. Artificial cerebrospinal fluid was pumped at a rate of 1.5 ,L/min in awake and freely moving animals and the dialysate was collected at 30-minute intervals. In one experiment, following a baseline period, rats were injected intraperitoneally with either physiological saline or 1 of 3 doses of alcohol, 0.8, 1.6, or 3.2 g ethanol/kg body weight. In a second experiment, following a baseline period, rats were applied a clothespin to the base of their tail for 20 minutes. The levels of dynorphin A1,8 in the dialysate were analyzed with solid-phase radioimmunoassay. Results: Relative to saline-treated controls, an alcohol dose of 1.6 and 3.2 g/kg caused a transient increase in the extracellular levels of dynorphin A1,8 in the first 30 minutes of alcohol administration. However, the effect resulting from the high 3.2 g/kg dose was far more pronounced and more significant than with the moderate dose. There was no effect of tail pinch on dynorphin A1,8 levels in the nucleus accumbens. Conclusions: In this experiment, a very high dose of alcohol was especially capable of stimulating dynorphin A1,8 release in the nucleus accumbens. Dynorphin release in the accumbens has been previously associated with aversive stimuli and may thus reflect a system underlying the aversive properties of high-dose alcohol administration. However, the lack of effect of tail-pinch stress in the present study suggests that dynorphin A1,8 is not released in response to all forms of stressful/aversive stimuli. [source]

A ventral prefrontal-amygdala neural system in bipolar disorder: a view from neuroimaging research

ACTA NEUROPSYCHIATRICA, Issue 5 2009
Fay Y. Womer
In the past decade, neuroimaging research has identified key components in the neural system that underlies bipolar disorder (BD). The ventral prefrontal cortex (VPFC) and amygdala are highly interconnected structures that jointly play a central role in emotional regulation. Numerous research groups have reported prominent structural and functional abnormalities within the VPFC and amygdala supporting their essential role in a neural system underlying the emotional dysregulation that is a core feature of BD. Findings in BD also include those in brain regions interconnected with the VPFC and amygdala, including the ventral striatum, hippocampus and the cerebellum. Abnormalities in these regions may contribute to symptoms that reflect disruption in functions sub-served by these structures, including motivational, mnemonic and psychomotor functions. This article will first review leads from behavioural neurology that implicated these neural system abnormalities in BD. It will then review findings from structural and functional imaging studies to support the presence of abnormalities within these neural system components in BD. It will also review new findings from studies using diffusion tensor imaging (DTI) that provide increasing evidence of abnormalities in the connections between these neural system components in BD. Emerging data supporting differences in this neural system during adolescence, as well as potential beneficial effects of treatment on structure and function will also be presented. Finally, the article will discuss the implications for future investigations, including those for early identification and treatment of BD. [source]

Ascending visceral regulation of cortical affective information processing

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2003
Gary G. Berntson
Abstract Over a century ago, William James proposed that strong emotions represent the perceptual consequences of somato-visceral feedback. Although the strong form of this conception is no longer viable, considerable evidence has accumulated indicating a range of visceral influences on higher neurobehavioural processes. This literature has only recently begun to consolidate, because earlier reports generally remained at the demonstration level, and pathways and mechanisms for such influences were uncertain. Recently, specific effects of visceral feedback have become apparent on cortical activity, cerebral auditory-evoked responses, anxiety, memory and behavioural aspects of immunological sickness. Moreover, considerable progress has been made recently in determining the specific neural pathways and systems underlying these actions, especially the role of noradrenergic projections from the nucleus of the tractus solitarius and the locus coeruleus to the amygdala in memory processes, and to the basal forebrain in the processing of anxiety-related information. The present paper highlights selected recent findings in this area, and outlines relevant structures and pathways involved in the ascending visceral influence on higher neurobehavioural processes. [source]

An ERP Study of Emotional Face Processing in the Adult and Infant Brain

CHILD DEVELOPMENT, Issue 1 2007
Jukka M. Leppänen
To examine the ontogeny of emotional face processing, event-related potentials (ERPs) were recorded from adults and 7-month-old infants while viewing pictures of fearful, happy, and neutral faces. Face-sensitive ERPs at occipital,temporal scalp regions differentiated between fearful and neutral/happy faces in both adults (N170 was larger for fear) and infants (P400 was larger for fear). Behavioral measures showed no overt attentional bias toward fearful faces in adults, but in infants, the duration of the first fixation was longer for fearful than happy faces. Together, these results suggest that the neural systems underlying the differential processing of fearful and happy/neutral faces are functional early in life, and that affective factors may play an important role in modulating infants' face processing. [source]