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Results for “Prefrontal Cortex/physiology”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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4 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Medial prefrontal cortex acetylcholine injection-induced hypotension: the role of hindlimb vasodilation

The injection of acetylcholine (ACh) into the cingulate region of the medial prefrontal cortex (MPFC) causes a marked fall in arterial blood pressure which is not accompanied by changes in heart rate. The purpose of the present study was to investigate the hemodynamic basis for this stimulus-induced hypotension in Sprague-Dawley rats. The study was designed to determine whether a change in the vascular resistance of hindlimb, renal or mesenteric vascular beds contributes to the fall in arterial pressure in response to ACh injection into the cingulate cortex. Miniature pulsed-Doppler flow probes were used to measure changes in regional blood flow and vascular resistance. The results indicated that the hypotensive response was largely due to a consistent and marked vasodilation in the hindlimb vascular bed. On this basis, an additional experiment was then undertaken to determine the mechanisms that contribute to hindlimb vasodilation. The effect of interrupting the autonomic innervation of one leg on the hindlimb vasodilator response was tested. Unilateral transection of the lumbar sympathetic chain attenuated the cingulate ACh-induced vasodilation in the ipsilateral, but not in the contralateral hindlimb. These results suggest that the hypotensive response to cingulate cortex-ACh injection is caused by skeletal muscle vasodilation mediated by a sympathetic chain-related vasodilator system.

Non-NASA Center↗
NASA NTRS2000

Neural activation during response competition

The flanker task, introduced by Eriksen and Eriksen [Eriksen, B. A., & Eriksen, C. W. (1974). Effects of noise letters upon the identification of a target letter in a nonsearch task. Perception & Psychophysics, 16, 143--149], provides a means to selectively manipulate the presence or absence of response competition while keeping other task demands constant. We measured brain activity using functional magnetic resonance imaging (fMRI) during performance of the flanker task. In accordance with previous behavioral studies, trials in which the flanking stimuli indicated a different response than the central stimulus were performed significantly more slowly than trials in which all the stimuli indicated the same response. This reaction time effect was accompanied by increases in activity in four regions: the right ventrolateral prefrontal cortex, the supplementary motor area, the left superior parietal lobe, and the left anterior parietal cortex. The increases were not due to changes in stimulus complexity or the need to overcome previously learned associations between stimuli and responses. Correspondences between this study and other experiments manipulating response interference suggest that the frontal foci may be related to response inhibition processes whereas the posterior foci may be related to the activation of representations of the inappropriate responses.

Brain Mapping/methods↗
NASA NTRS2001

Stimulus-response incompatibility activates cortex proximate to three eye fields

We used functional magnetic resonance imaging (fMRI) to investigate cortical activation during the performance of three oculomotor tasks that impose increasing levels of cognitive demand. (1) In a visually guided saccade (VGS) task, subjects made saccades to flashed targets. (2) In a compatible task, subjects made leftward and rightward saccades in response to foveal presentation of the uppercase words "LEFT" or "RIGHT." (3) In a mixed task, subjects made rightward saccades in response to the lowercase word "left" and leftward saccades in response to the lowercase word "right" on incompatible trials (60%). The remaining 40% of trials required compatible responses to uppercase words. The VGS and compatible tasks, when compared to fixation, activated the three cortical eye fields: the supplementary eye field (SEF), the frontal eye field (FEF), and the parietal eye field (PEF). The mixed task, when compared to the compatible task, activated three additional cortical regions proximate to the three eye fields: (1) rostral to the SEF in medial frontal cortex; (2) rostral to the FEF in dorsolateral prefrontal cortex (DLPFC); (3) rostral and lateral to the PEF in posterior parietal cortex. These areas may contribute to the suppression of prepotent responses and in holding novel visuomotor associations in working memory. Copyright 2001 Academic Press.

NASA Discipline Neuroscience↗