Somatotopic Map and Inter- and Intra-Digit Distance in Brodmann Area 2 by Pressure Stimulation

Abstract

The somatotopic representation of the tactile stimulation on the finger in the brain is an essential part of understanding the human somatosensory system as well as rehabilitation and other clinical therapies. Many studies have used vibrotactile stimulations and reported finger somatotopic representations in the Brodmann area 3 (BA 3). On the contrary, few studies investigated finger somatotopic representation using pressure stimulations. Therefore, the present study aimed to find a comprehensive somatotopic representation (somatotopic map and inter- and intra-digit distance) within BA 2 of humans that could describe tactile stimulations on different joints across the fingers by applying pressure stimulation to three joints-the first (p1), second (p2), and third (p3) joints-of four fingers (index, middle, ring, and little finger). Significant differences were observed in the inter-digit distance between the first joints (p1) of the index and little fingers, and between the third joints (p3) of the index and little fingers. In addition, a significant difference was observed in the intra-digit distance between p1 and p3 of the little finger. This study suggests that a somatotopic map and inter- and intra-digit distance could be found in BA 2 in response to pressure stimulation on finger joints.

Effects of sensorimotor training on memory and brain plasticity in persons with amnestic mild cognitive impairment

“…78 Fingertip activations were analysed within the anatomically defined and joined Brodmann areas 1 and 2 (BA1&2) in the left primary somatosensory cortex (S1) cortex, separately for each participant (using FreeSurfer 6.0), 72,84,85 as target regions for the somatotopic representation of the hand. [86][87][88] Results were controlled for family-wise Type 1 error, 89 and represented in standard Montreal Neurological Institute (MNI) 305 space. 77 For paired associates learning, delayed matching to sample, pattern recognition memory and spatial recognition memory three repeated measures were considered (pre-, post-straining and follow-up), thus delta is Δ is the value at FU minus value at T1; for all other measures Δ is the value at T2 minus value at T1 c Group differences between ET and CT group pre-training were tested using t-test 95 ; CI, confidence interval; bold significant p-value above alpha inflation threshold (computed using the false discovery rate); bold* significant p-value below alpha inflation threshold b For paired associates learning, delayed matching to sample, pattern recognition memory and spatial recognition memory (i.e.…”

“…71,72,84,85 These regions are relevant for the somatotopic representation of the hand using pressure stimuli. [86][87][88] General linear modelling applied to individual data provided the estimate of the cortical location of each digit in BA1&2 (after the correction for multiple comparisons using a Monte-Carlo simulation), 89 represented by the centre of mass of the respective activation cluster (see Figure 3). 87 The relative distance between each pair of digits was determined along the cortical surface, 90,91 and the sum of relative distances of the thumb to all other digits, here called finger distance, was taken as outcome to represent somatotopic effects of the two trainings (see Supplement S11).…”