title: Inter- and Intradigit Somatotopic Map of High-Frequency Vibration Stimulations in Human Primary Somatosensory Cortex.
abstract: Although more about the somatotopic mapping of fingers continues to be uncovered, there is lack of mapping attempts regarding the integration of within-finger and across-finger somatotopic coordinates in Broadmann area (BA) 3. This study aimed to address the issue by finding an inter-/intradigit somatotopic map with high-frequency (250 Hz) vibrotactile stimulation. Functional magnetic resonance imaging (fMRI) data were acquired while stimulation was applied to 3 phalanxes (distal [p1], intermediate [p2], and proximal [p3] phalanx) of 4 fingers (index, middle, ring, and little finger) for a total of 12 finger-phalanx combinations for a human. Inter-, intra-, and inter-/intradigit distances were calculated from peak activation coordinates in BA 3 for each combination. With regard to interdigit dimensions, the somatotopic coordinates proceeded in the lateral-to-medial direction for the index, middle, ring, and little fingers consecutively. This trend is comparable to that generated from low-frequency stimulation modalities (flutter stimulation). The somatotopic distances between fingers were greatest when p1 was compared across fingers. From an intradigit perspective, stimulation on p1, p2, and p3 yielded BA 3 peak coordinates aligned along the anterior-to-posterior and inferior-to-superior directions for all fingers. An inter-/intradigit map exhibited a radially propagating trend of distances calculated with respect to index p1 as a reference point; this provided an integrated view of inter- and intradigit somatotopies, which are traditionally discussed separately. We expect such an inter-/intradigit somatotopic map approach to contribute in generating a comprehensive somatotopic model of fingers.
authors.affiliation: From the Department of Biomedical Engineering, Research Institute of Biomedical Engineering, College of Biomedical & Health Science, Konkuk University, Chungju (M-HC, H-SK, S-CC); and Department of Human and Systems Engineering, Ulsan National Institute of Science and Technology, Ulsan (S-PK), South Korea.
authors.forename: Mi-Hyun
authors.initials: MH
authors.lastname: Choi
authors.forename: Sung-Phil
authors.initials: SP
authors.lastname: Kim
authors.forename: Hyung-Sik
authors.initials: HS
authors.lastname: Kim
authors.forename: Soon-Cheol
authors.initials: SC
authors.lastname: Chung
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005385:Fingers / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010812:Physical Stimulation; D013003:Somatosensory Cortex / Q000000981:diagnostic imaging / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology*; D014732:Vibration; D055815:Young Adult