Functional characteristics of the human primary somatosensory cortex: An electrostimulation study

Area of Science:

• Neuroscience
• Human Somatosensory Cortex Function

Background:

• The functional organization of the human primary somatosensory cortex (S1), particularly Brodmann area (BA) 1, is well-established through electrical stimulation studies.
• However, the functional understanding of the deeper surfaces of S1 (BA 2 and 3) remains limited.

Purpose of the Study:

• To investigate the functional characteristics of the entire primary somatosensory cortex (S1), including its deep surfaces.
• To analyze clinical manifestations from extra-operative cortical electrical stimulation (ES) in patients with medically intractable epilepsy.

Main Methods:

• Retrospective analysis of clinical data from 33 epilepsy patients undergoing stereo-electroencephalography (SEEG) monitoring.
• Electrical stimulation (ES) of 244 sites within S1, recording positive responses, types of responses, and body regions involved.

Main Results:

• 81.1% of stimulated S1 sites (198/244) yielded positive responses, predominantly in the sulcal cortex.
• No demographic or clinical factors predicted response occurrence or threshold.
• The size of the body region involved in responses showed a significant association with the stimulated Brodmann area (BA) site (p < 0.001).

Conclusions:

• This study provides insights into the functional organization of the entire S1, challenging previous limited views.
• The findings demonstrate the diverse functions of S1, particularly highlighting the importance of its deep surfaces.