Brain activation by central command during actual and imagined handgrip under hypnosis

Departments of 1 Physical Therapy and 3 Radiology and the 2 Moss Heart Center, University of Texas Southwestern Medical Center, Dallas 75390-8876; and 4 Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas 76107; and 5 Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin 53706 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