The perception of touch and the ventral somatosensory pathway

Abstract

In humans, touching the skin is known to activate, among others, the contralateral primary somatosensory cortex on the postcentral gyrus together with the bilateral parietal operculum (i.e. the anatomical site of the secondary somatosensory cortex). But which brain regions beyond the postcentral gyrus specifically contribute to the perception of touch remains speculative. In this study we collected structural magnetic resonance imaging scans and neurological examination reports of patients with brain injuries or stroke in the left or right hemisphere, but not in the postcentral gyrus as the entry site of cortical somatosensory processing. Using voxel-based lesion-symptom mapping, we compared patients with impaired touch perception (i.e. hypoaesthesia) to patients without such touch impairments. Patients with hypoaesthesia as compared to control patients differed in one single brain cluster comprising the contralateral parietal operculum together with the anterior and posterior insular cortex, the putamen, as well as subcortical white matter connections reaching ventrally towards prefrontal structures. This finding confirms previous speculations on the 'ventral pathway of somatosensory perception' and causally links these brain structures to the perception of touch.

Pain and temperature processing in dementia: a clinical and neuroanatomical analysis

“…These findings substantiate current formulations of the neural organization of central somatosensory and homeostatic signal processing ( Craig, 2002 , 2009 ; Borsook, 2012 ; Preusser et al , 2015 ). Peripheral somatic and visceral sensory afferents conveying pain and thermal information relay via postero-lateral thalamic nuclei to somatosensory cortex (Brodmann area 3a) and dorsal posterior insula ( Craig, 2002 ).…”

Regional gray matter volume and structural network strength in somatic vs. non-somatic delusional disorders

“…This was unexpected given that DI patients usually suffer from intense sensations in their skin or body. However, converging evidence suggests that perception of touch in humans does not only require the postcentral gyrus and parietal operculum but also involves the insular cortex and putamen together with prefrontal structures as well as superior temporal and limbic structures (Nagy et al, 2006;Auksztulewicz et al, 2012Preusser et al, 2015. We also found evidence for structural brain changes in insular cortex, a brain region known to mediate feelings of disgust and as a potential source of interoceptive predictions (Wicker et al, 2003;Craig, 2003;Paulus and Stein, 2009).…”

Same Intervention–Different Reorganization

“…55 In patients with somatosensory impairment following thalamic/capsular lesions we found activation of ipsilesional insula postintervention, a region known to have a role, together with S1 and S2, in tactile learning and memory. 29,41 While activation of S1 was not significant at a group level postintervention, ipsilesional insula is within the distributed neural network required for the task of tactile learning and discrimination.…”