Differential responses of the insular cortex gyri to autonomic challenges

Abstract

Determining insular functional topography is essential for assessing autonomic consequences of neural injury. We examined that topography in the five major insular cortex gyri to three autonomic challenges, the Valsalva, hand grip, and foot cold pressor, using functional magnetic resonance imaging (fMRI) procedures. Fifty-seven healthy subjects (age±std: 47±9 years) performed four 18 s Valsalva maneuvers (30 mmHg load pressure), four hand grip challenges (16 s at 80% effort), and a foot cold pressor (60 s, 4°C), with fMRI scans recorded every 2 s. Signal trends were compared across gyri using repeated measures ANOVA. Significantly (P<0.05) higher signals in left anterior versus posterior gyri appeared during Valsalva strain, and in the first 4 s of recovery. The right anterior gyri showed sustained higher signals up to 2 s post-challenge, relative to posterior gyri, with sub-gyral differentiation. Left anterior gyri signals were higher than posterior areas during the hand grip challenge. All right anterior gyri showed increased signals over posterior up to 12 s post-challenge, with decline in the most-anterior gyrus from 10–24 s during recovery. The left three anterior gyri showed relatively lower signals only during the 90 s recovery of the cold pressor, while the two most-anterior right gyri signals increased only during the stimulus. More-differentiated representation of autonomic signals appear in the anterior right insula for the Valsalva maneuver, a bilateral, more-posterior signal representation for hand grip, and preferentially right-sided, anterior-posterior representation for the cold pressor. The functional organization of the insular cortex is gyri-specific to unique autonomic challenges.

Autonomic responses to exercise: Cortical and subcortical responses during post-exercise ischaemia and muscle pain

“…Previous neuroimaging studies have shown that the insula is activated during physiological manouevres that increase MSNA, including the Valsalva manoeuvre (Henderson et al, 2002;Macey et al, 2012)), inspiratorycapacity apnoea , cold-pressor test (Harper et al, 2003;Macey et al, 2012), hand-grip exercise (Wong et al, 2007a(Wong et al, , 2007bSander et al, 2010;Macey et al, 2012) and lower-body negative pressure (Kimmerly et al, 2005). Moreover, there is evidence for regional specialization of the insula for different autonomic challenges (Macey et al, 2012). It is known from work in experimental animals that the insula does not project directly to the RVLM but does project to the lateral posterior hypothalamus (Cechetto and Chen, 1990), so may mediate its cardiovascular effects via indirect projections to the hypothalamus.…”

Blood Pressure Variability in Acute Ischemic Stroke: Influence of Infarct Location in the Insular Cortex

“…In addition, the anterior and posterior regions of the insular cortex were shown to have different roles. The findings from a previous study on the insular cortex using 3 examinations of the autonomic function (Valsalva maneuvers, 4 hand grip challenges, and a foot cold pressor) with functional MRI indicated that the right anterior insular cortex was associated with sympathetic activity [9]. A study examining the effects of the location of acute ischemic stroke including the insular cortex on the levels of troponin and their relative temporal changes demonstrated a prominent role of the right dorsal anterior insular cortex in the parasympathetic control of cardiac and autonomic functions [28].…”

The Insular Cortex and the Regulation of Cardiac Function

“…Variations in the lateralization as well as the anteroposterior representation of insular regulation may partially depend on the nature of the eliciting stimulus (128,198). Using three different stimuli (Valsalva maneuver, right hand grip, and cold pressor challenge), fMRI responses were correlated with respect to insular location.…”