Ipsilateral Area 3b Responses to Median Nerve Somatosensory Stimulation

• Published in: NeuroImage (Orlando, Fla.) Vol. 18; no. 1; pp. 169 - 177
• Main Authors: Kanno, Akitake, Nakasato, Nobukazu, Hatanaka, Keisaku, Yoshimoto, Takashi
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 2003; Elsevier Limited
• Subjects: Adult; Aged; Brain Diseases - diagnosis; Brain Diseases - physiopathology; central sulcus; Dominance, Cerebral - physiology; Electric Stimulation; Evoked Potentials, Somatosensory - physiology; Female; Hand - innervation; hand area; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Magnetoencephalography; Male; Median Nerve - physiopathology; Middle Aged; primary somatosensory cortex; Reaction Time - physiology; Signal Processing, Computer-Assisted; Somatosensory Cortex - physiopathology; somatosensory evoked potential; somatosensory evoked potential; primary somatosensory cortex; central sulcus; magnetoencephalography; hand area
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1006/nimg.2002.1283

Magnetoencephalography investigation of the somatosensory evoked fields for median nerve stimulation detected ipsilateral area 3b responses in 18 hemispheres of 14 (1 normal subject and 13 patients with brain diseases) among 482 consecutive subjects. The major three peaks in the ipsilateral response were named iP50m, iN75m, and iP100m, based on the current orientation in the posterior, anterior, and posterior directions and the latency of 52.7 ± 6.2, 74.1 ± 9.4, and 100.2 ± 15.8 ms (mean ± standard deviation), respectively. The moment of the iP50m dipole (9.4 ± 5.7 nAm) was significantly smaller than that of the N20m dipole of the contralateral response (cN20m, 27.5 ± 10.5 nAm, P < 0.0001). Dipoles of iP50m and cN20m were similarly localized on the posterior bank of the central sulcus. iP50m in the present study had the same current orientation as and peak latency similar to that of the first ipsilateral primary somatosensory response to lip stimulation in our previous report. Therefore, the somatosensory afferent pathway from the hand may reach directly to the ipsilateral area 3b at least in part of the human population.