Abstract
Neurons in the somatosensory cortex are exquisitely sensitive to mechanical stimulation of the skin surface. The location, velocity, direction, and adaptation of tactile stimuli on the skin’s surface are discriminable features of somatosensory processing, however the representation and processing of dynamic tactile arrays in the human somatosensory cortex are poorly understood. The principal aim of this study was to map the relation between dynamic saltatory pneumatic stimuli at discrete traverse velocities on the glabrous hand and the resultant pattern of evoked BOLD response in the human brain. Moreover, we hypothesized that the hand representation in contralateral Brodmann Area (BA) 3b would show a significant dependence on stimulus velocity. Saltatory pneumatic pulses (60 ms duration, 9.5 ms rise/fall) were repetitively sequenced through a 7-channel TAC-Cell array at traverse velocities of 5, 25, and 65 cm/s on the glabrous hand initiated at the tips of D2 (index finger) and D3 (middle finger) and sequenced towards the D1 (thumb). The resulting hemodynamic response was sampled during 3 functional MRI scans (BOLD) in 20 neurotypical right-handed adults at 3T. Results from each subject were inserted to the one-way ANOVA within-subjects and one sample t-test to evaluate the group main effect of all three velocities stimuli and each of three different velocities, respectively. The stimulus evoked BOLD response revealed a dynamic representation of saltatory pneumotactile stimulus velocity in a network consisting of the contralateral primary hand somatosensory cortex (BA3b), associated primary motor cortex (BA4), posterior insula, and ipsilateral deep cerebellum. The spatial extent of this network was greatest at the 5 and 25 cm/s pneumotactile stimulus velocities.
Highlights
Animal and human models of brain plasticity have shown that the development of functional motor tasks depend on the interplay between sensory input and motor output [1, 2]
Significant Blood-oxygen-level dependent (BOLD) responses were localized to the sensorimotor cortex which includes the postcentral gyrus (S1, S2), primary and premotor cortex, posterior insula, and deep cerebellum
We used a new saltatory pneumotactile stimulus modality programmed at 3 different velocities on the glabrous hand to map the evoked hemodynamic BOLD response in cortical and subcortical somatosensory areas using functional Magnetic Resonance Imaging (fMRI) methods
Summary
The principal aim of this study was to map the relation between dynamic saltatory pneumatic stimuli at discrete traverse velocities on the glabrous hand and the resultant pattern of evoked BOLD response in the human brain. The primary goal of the present study was to functionally map the human brain to identify the relation between saltatory pneumotactile stimulation at 3 velocities on the glabrous hand and the evoked hemodynamic BOLD response in select regions of interest (ROIs), including cerebral somatosensory areas (S1, S2, PPC, posterior insula), and deep cerebellum among 20 neurotypical adults using high-resolution fMRI methods
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