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The purpose was to compare patterns of brain activation during imagined handgrip exercise and identify cerebral cortical structures participating in "central" cardiovascular regulation. Subjects screened for hypnotizability, five with higher (HH) and four with lower hypnotizability (LH) scores, were tested under two conditions involving 3 min of 1) static handgrip exercise (HG) at 30% of maximal voluntary contraction (MVC) and 2) imagined HG (I-HG) at 30% MVC. Force (kg), forearm integrated electromyography, rating of perceived exertion, heart rate (HR), mean blood pressure (MBP), and differences in regional cerebral blood flow distributions were compared using an ANOVA. During HG, both groups showed similar increases in HR (+13 +/- 5 beats/min) and MBP (+17 +/- 3 mmHg) after 3 min. However, during I-HG, only the HH group showed increases in HR (+10 +/- 2 beats/min; P < 0.05) and MBP (+12 +/- 2 mmHg; P < 0.05). There were no significant increases or differences in force or integrated electromyographic activity between groups during I-HG. The rating of perceived exertion was significantly increased for the HH group during I-HG, but not for the LH group. In comparison of regional cerebral blood flow, the LH showed significantly lower activity in the anterior cingulate (-6 +/- 2%) and insular cortexes (-9 +/- 4%) during I-HG. These findings suggest that cardiovascular responses elicited during imagined exercise involve central activation of insular and anterior cingulate cortexes, independent of muscle afferent feedback; these structures appear to have key roles in the central modulation of cardiovascular responses.

Intensive task-specific rehabilitative training, such as robotic BWSTT, can promote supraspinal plasticity in the motor centers known to be involved in locomotion. Furthermore, improvement in over-ground locomotion is accompanied by an increased activation of the cerebellum.

. Activation of the insular cortex is affected by the intensity of exercise. J. Appl. Physiol. 87(3): 1213-1219, 1999.-The purpose of this investigation was to determine whether there were differences in the magnitude of insular cortex activation across varying intensities of static and dynamic exercise. Eighteen healthy volunteers were studied: eight during two intensities of leg cycling and ten at different time periods during sustained static handgrip at 25% maximal voluntary contraction or postexercise cuff occlusion. Heart rate, blood pressure (BP), perceived exertion, and regional cerebral blood flow (rCBF) distribution data were collected. There were significantly greater increases in insular rCBF during lower (6.3 Ϯ 1.7%; P Ͻ 0.05) and higher (13.3 Ϯ 3.8%; P Ͻ 0.05) intensity cycling and across time during static handgrip (change from rest for right insula at 2-3 min, 3.8 Ϯ 1.1%, P Ͻ 0.05; and at 4-5 min, 8.6 Ϯ 2.8%, P Ͻ 0.05). Insular rCBF was decreased during postexercise cuff occlusion (Ϫ5.5 Ϯ 1.2%; P Ͻ 0.05) with BP sustained at exercise levels. Right insular rCBF data, but not left, were significantly related, with individual BP changes (r 2 ϭ 0.80; P Ͻ 0.001) and with ratings of perceived exertion (r 2 ϭ 0.79; P Ͻ 0.01) during exercise. These results suggest that the magnitude of insular activation varies with the intensity of exercise, which may be further related to the level of perceived effort or central command.human; brain; single-photon emission-computed tomography; magnetic resonance imaging; autonomic nervous system THE CEREBRAL CORTEX HAS long been recognized as having an important role in the regulation of autonomic function; this realization occurred even before the identification of any specific cortical region (10, 12). Studies implicating various cerebral cortical regions as possible sites for autonomic regulation were reviewed by Cechetto and Saper (3). Using specific criteria, they concluded that the insular cortex played a significant role. The insular cortex is a forebrain autonomic nucleus involved in the integration of sensory and visceral information (26). Of particular interest is the role played by the insular cortex in cardiovascular regulation (6,11,17,18,23,24). The right and left insular cortices possess reciprocal connectivity with numerous subcortical sites, including the lateral hypothalamus (31), ventrolateral medulla (31), and the nucleus tractus solitarii (NTS) (20, 31). These specific subcortical sites are known to be prominently involved in cardiovascular regulation at rest, as well as during physical activity (27). During exercise, when blood pressure (BP) must be regulated to sustain flow to both the brain and working musculature, signals from higher cortical centers (central command) and muscle afferent input (exercise pressor reflex) from the working limbs appear to converge at these sites to dictate an integrated cardiovascular response (16,27).Activation of the insular cortex has been shown to occur during volitional exercise (29). However, there was no si...

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