Forss N, Jousmäki V, Hari R. Interaction between afferent input from fingers in human somatosensory cortex.
Brain Res 1995;
685:68-76. [PMID:
7583255 DOI:
10.1016/0006-8993(95)00424-o]
[Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We recorded somatosensory evoked magnetic fields from eight healthy subjects with a 122-channel whole-scalp SQUID magnetometer. The stimulus sequence consisted of 'standard' stimuli (85%) delivered to palmar side of the left thumb with an interstimulus interval of 0.6 s and of 'deviants' (15%), randomly interspersed among the standards, to little finger, and vice versa. Both stimuli activated four source areas: the contralateral primary somatosensory cortex (SI), the contra-and ipsilateral secondary somatosensory cortices (SII), and the contralateral posterior parietal cortex (PPC). The short-latency (20-40 ms) responses originated in the SI cortex, whereas long-latency responses arose from all 4 areas. At SII and PPC, the deviant stimuli elicited larger responses when presented alone, without intervening standards, than among standards. This implies interaction between afferent impulses from the two fingers and/or partly intermingled cortical representations. Our findings show, in agreement with animal data, different excitatory/inhibitory balance in the various somatosensory areas.
Collapse