Tactile direction discrimination in humans after stroke

• Published in: Brain communications 2020-01, Vol.2 (2), p.fcaa088-fcaa088
• Main Authors: Lundblad, Linda C, Olausson, Håkan, Wasling, Pontus, Jood, Katarina, Wysocka, Anna, Hamilton, J Paul, McIntyre, Sarah, Backlund Wasling, Helena
• Format: Article
• Language: English
• Subjects: cortical activation; direction discrimination; grip force control; motion; Neurosciences; Neurosciences & Neurology; Neurovetenskaper; object manipulation; operculum; Original; parietal; perception; sensibility; sensitivity; sensory loss; somatosensory system; stroke; structural MRI; touch
• ISSN: 2632-1297; 2632-1297
• DOI: 10.1093/braincomms/fcaa088

Abstract Sensing movements across the skin surface is a complex task for the tactile sensory system, relying on sophisticated cortical processing. Functional MRI has shown that judgements of the direction of tactile stimuli moving across the skin are processed in distributed cortical areas in healthy humans. To further study which brain areas are important for tactile direction discrimination, we performed a lesion study, examining a group of patients with first-time stroke. We measured tactile direction discrimination in 44 patients, bilaterally on the dorsum of the hands and feet, within 2 weeks (acute), and again in 28 patients 3 months after stroke. The 3-month follow-up also included a structural MRI scan for lesion delineation. Fifty-nine healthy participants were examined for normative direction discrimination values. We found abnormal tactile direction discrimination in 29/44 patients in the acute phase, and in 21/28 3 months after stroke. Lesions that included the opercular parietal area 1 of the secondary somatosensory cortex, the dorsolateral prefrontal cortex or the insular cortex were always associated with abnormal tactile direction discrimination, consistent with previous functional MRI results. Abnormal tactile direction discrimination was also present with lesions including white matter and subcortical regions. We have thus delineated cortical, subcortical and white matter areas important for tactile direction discrimination function. The findings also suggest that tactile dysfunction is common following stroke. We examined a group of patients with first time stroke to study which brain regions are important for tactile direction discrimination. We found impairment associated with lesions in previously identified somatosensory, insular, and prefrontal cortical areas. In addition, we found impairment associated with lesions in subcortical and white matter areas. Graphical Abstract Graphical Abstract