The existence of visual information processing streams in the cortex is well established, but what about the somatosensory system? A hallmark of a processing stream is a hierarchical organization of the neuronal response properties along an anatomically distinct pathway. In search of such hierarchical organization, we applied full-body somatosensory stimulation under functional MRI. We considered two measures of hierarchy: (1) selectivity – whether cortical response is restricted to a single body part stimulation, as opposed to several body parts, and (2) laterality, the extent to which the cortex responses are restricted to the stimulation of the contralateral body side. We found that both selectivity and laterality decrease as we move away from the primary somatosensory cortex in three directions, providing evidence for somatosensory hierarchical gradients.
Paper of the month
Loewenstein's Lab: Hierarchical cortical gradients in somatosensory processing
Noam Saadon-Grosman, ShaharArzy, Yonatan Loewenstein
NeuroImage, Volume 222, 2020, 117257, ISSN 1053-8119, (2020)