Activation of the insular cortex is affected by the intensity of exercise

Abstract

. 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...

Neurohumoral responses during prolonged exercise in humans

“…38). It has been a matter of debate whether physical activity is associated with an overall activation of the brain (30,39), but it is incontrovertible that exercise activates several regions of the brain in an intensity-dependent manner (16,44,57). Although the mechanical power output remained constant during exercise, increased difficulty in retaining power at the end of the hyperthermic cycle trial was reflected in the subjects' RPE, and it appears that brain areas associated with "central command" are activated when the "mental effort" associated with exercise is enhanced (58).…”

A prominent role for amygdaloid complexes in the Variability in Heart Rate (VHR) during Rapid Eye Movement (REM) sleep relative to wakefulness

“…In normal humans, rCBF in the right insula covaries with heart rate (Critchley et al, 2000). Functional magnetic resonance imaging (fMRI) recently confirmed the functional links between the insular cortex and the modulation of heart rate (Williamson et al, 1997(Williamson et al, , 1999Critchley et al, 2000). The activity in the left insula increases during dynamic exercise (cycling) but not passive exercise (cycling movement induced by moving pedals independently) (Williamson et al, 1997(Williamson et al, , 1999.…”

“…Intraoperative electrical stimulation of the insula elicits changes in heart rate and blood pressure (Oppenheimer et al, 1992). In normal subjects, functional neuroimaging studies showed that in response to physical exercise (Williamson et al, 1997(Williamson et al, , 1999 and mental stressor tasks (Critchley et al, 2000), both associated with significantly increased heart rate, the activity in both insula covaried with heart rate.…”

Altered Insula Connectivity under MDMA

“…While activity of the insula has been linked to exercise-induced hypertension (Williamson et al, 1999), bradycardia (Volkow et al, 2000), and heart-rate variability (Critchley et al, 2003;Chang et al, 2013), we are not aware of any studies that have found low-level changes in physiology (eg, tachycardia or hypertension) to change insula connectivity per se (ie, when taking the insular cortex as a seed region of interest).…”