Electrocorticographic changes in field potentials following natural somatosensory percepts in humans
Restoration of somatosensory deficits in humans requires a clear understanding of the neural representations of percepts. To characterize the cortical response to naturalistic somatosensation, we examined field potentials in the primary somatosensory cortex of humans.
Four patients with intractable epilepsy were implanted with subdural electrocorticography (ECoG) electrodes over the hand area of S1. Three types of stimuli were applied, soft-repetitive touch, light touch, and deep touch. Power in the alpha (8–15 Hz), beta (15–30 Hz), low-gamma (30–50 Hz), and high-gamma (50–125 Hz) frequency bands were evaluated for significance.
Seventy-seven percent of electrodes over the hand area of somatosensory cortex exhibited changes in these bands. High-gamma band power increased for all stimuli, with concurrent alpha and beta band power decreases. Earlier activity was seen in these bands in deep touch and light touch compared to soft touch.
These findings are consistent with prior literature and suggest a widespread response to focal touch, and a different encoding of deeper pressure touch than soft touch.
KeywordsSomatosensory Brain Computer Interface (BCI) Brain Machine Interface (BMI) Electrocorticography Cortical Stimulation
We wish to acknowledge the generous support of Cal-BRAIN: A Neurotechnology Program for California, National Center for Advancing Translational Science (NCATS) of the U.S. National Institutes of Health (KL2TR001854), National Institutes of Health (R25 NS099008-01), The Neurosurgery Research and Education Foundation (NREF), the Tianqiao and Chrissy Chen Brain-machine Interface Center at Caltech, the Boswell Foundation and the Della Martin Foundation, and the University of Southern California Neurorestoration Center. None of the listed sources of funding had a role in study collection, analysis, interpretation of data, or writing of the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest involved with this or related work.
All research herein complies with institutional and international guidelines on research involving human participants, and was conducted after approval by the institutional review board (study approval HS-13-00528). Informed consent was obtained from all individual participants included in the study. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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