Introduction: We sought to understand the neurophysiological response properties of neurons in the hand area of primary somatosensory cortex (S1) via ECoG during mechanical touch of the subject’s hand.

Methods: Two patients with epilepsy were implanted with subdural ECoG grids over S1 in the hand area. These patients had either a “mini”-ECoG grid consisting of 64, 2-mm contacts, spaced 3-mm apart (21 F, left sided implant) or a “standard”-ECoG grid consisting of 20, 5-mm contacts, spaced 10-mm apart (25 M, right sided implant). A region on the hand that correlated to the contralateral cortex covered by the grid was subject to 15 trials each of three types of mechanical touch: soft touch (cotton gauze lightly brushed repetitively), light touch with a tongue depressor (no indentation of the skin), and deep touch with a tongue depressor (indentation of the skin). Local field potential from these trials was then analyzed off-line. Power was calculated and normalized, and then evaluated for significance using a permutation test (N=10,000).

Results: All three types of touch showed significant decreases in power in the alpha (8-12 Hz) and beta (12-40 Hz) bands immediately following the onset of touch and returning to baseline around 400ms after onset in the electrode pair associated with the dermatomal region. The spread of gamma band activity (40-170 Hz) showed a significant increase in power centered around 300ms after touch onset and extinguishing around 600ms. All changes happen earlier in deep touch than light or soft touch. The decrease in alpha and beta power was found in the electrodes surrounding the primary two electrodes extended throughout the grid.

Conclusions: Decreases in alpha and beta band power were associated with touch onset as well as an increase in gamma power centered over the area of S1 associated with the area of touch; similar to prior work.

Patient Care: This study is preliminary work in efforts to create artificial sensation through somatosensory cortical stimulation for individuals with loss of sensation from paralysis, stroke, loss of limb, or other disease processes.

Learning Objectives: By the conclusion of this session, participants should be able 1) Describe the importance of changes in alpha, beta, and gamma power following mechanical touch. 2) Discuss, in small groups, the implications of changes in frequency bands from mechanical touch in terms of encoding percepts. 3) Identify an effective strategy for creating artificial sensation in a somatosensory brain computer interface system.

References: National Spinal Cord Injury Statistical Center, Facts and Figures At a Glance. Birmingham, AL: University of Alabama at Birmingham, March 2013. [Online]. [Accessed October 25th 2015]. Agnew, W.F., and Mccreery, D.B. (1987). Considerations for safety in the use of extracranial stimulation for motor evoked potentials. Neurosurgery 20, 143-147. Andersen, R.A., Burdick, J.W., Musallam, S., Pesaran, B., and Cham, J.G. (2004a). Cognitive neural prosthetics. Trends Cogn Sci 8, 486-493. Andersen, R.A., and Cui, H. (2009). Intention, action planning, and decision making in parietal-frontal circuits. Neuron 63, 568-583. Andersen, R.A., Hwang, E.J., and Mulliken, G.H. (2010). Cognitive neural prosthetics. Annu Rev Psychol 61, 169-190, C161-163. Andersen, R.A., Musallam, S., and Pesaran, B. (2004b). Selecting the signals for a brain-machine interface. Curr Opin Neurobiol 14, 720-726. Arzy, S., Thut, G., Mohr, C., Michel, C.M., and Blanke, O. (2006). Neural basis of embodiment: distinct contributions of temporoparietal junction and extrastriate body area. Journal of Neuroscience 26, 8074-8081. Botvinick, M., and Cohen, J. (1998). Rubber hands' feel'touch that eyes see. Nature 391, 756. Cronin, J., Wu, J., Collins, K., Sarma, D., Rao, R., Ojemann, J., and Olson, J. (2016). Task-Specific Somatosensory Feedback via Cortical Stimulation in Humans. IEEE Transactions on Haptics PP, 1-1. Dadarlat, M.C., O'doherty, J.E., and Sabes, P.N. (2015). A learning-based approach to artificial sensory feedback leads to optimal integration. Nature neuroscience 18, 138-144. Fagg, A.H., Hatsopoulos, N.G., London, B.M., Reimer, J., Solla, S.A., Wang, D., and Miller, L.E. (2009). Toward a biomimetic, bidirectional, brain machine interface. Conf Proc IEEE Eng Med Biol Soc 2009, 3376-3380. Flesher, S.N., Collinger, J.L., Foldes, S.T., Weiss, J.M., Downey, J.E., Tyler-Kabara, E.C., Bensmaia, S.J., Schwartz, A.B., Boninger, M.L., and Gaunt, R.A. (2016). Intracortical microstimulation of human somatosensory cortex. Science Translational Medicine. Gallagher, S., and Cole, J. (1995). Body image and body schema in a deafferented subject. The journal of mind and behavior, 369-389. Hiremath, S.V., Tyler-Kabara, E.C., Wheeler, J.J., Moran, D.W., Gaunt, R.A., Collinger, J.L., Foldes, S.T., Weber, D.J., Chen, W., Boninger, M.L., and Wang, W. (2017). Human perception of electrical stimulation on the surface of somatosensory cortex. PLOS ONE 12, e0176020. Hochberg, L.R., Serruya, M.D., Friehs, G.M., Mukand, J.A., Saleh, M., Caplan, A.H., Branner, A., Chen, D., Penn, R.D., and Donoghue, J.P. (2006). Neuronal ensemble control of prosthetic devices by a human with tetraplegia. Nature 442, 164-171. Johnson, L.A., Wander, J.D., Sarma, D., Su, D.K., Fetz, E.E., and Ojemann, J.G. (2013). Direct electrical stimulation of somatosensory cortex in humans using electrocorticography electrodes: a qualitative and quantitative report. Journal of neural engineering 10, 036021-036021. Kaas, J.H., Nelson, R.J., Sur, M., Lin, C.S., and Merzenich, M.M. (1979). Multiple representations of the body within the primary somatosensory cortex of primates. Science 204, 521-523. Kim, S.P., Simeral, J.D., Hochberg, L.R., Donoghue, J.P., Friehs, G.M., and Black, M.J. (2011). Point-and-click cursor control with an intracortical neural interface system by humans with tetraplegia. IEEE Trans Neural Syst Rehabil Eng 19, 193-203. Klaes, C., Shi, Y., Kellis, S., Minxha, J., Revechkis, B., and Andersen, R.A. (2014). A cognitive neuroprosthetic that uses cortical stimulation for somatosensory feedback. Journal of neural engineering 11, 056024. Lee, B., Liu, C.Y., and Apuzzo, M.L. (2013). A primer on brain-machine interfaces, concepts, and technology: a key element in the future of functional neurorestoration. World Neurosurg 79, 457-471. Marzullo, T.C., Lehmkuhle, M.J., Gage, G.J., and Kipke, D.R. (2010). Development of closed-loop neural interface technology in a rat model: combining motor cortex operant conditioning with visual cortex microstimulation. IEEE Trans Neural Syst Rehabil Eng 18, 117-126. O'doherty, J.E., Lebedev, M.A., Ifft, P.J., Zhuang, K.Z., Shokur, S., Bleuler, H., and Nicolelis, M.A. (2011). Active tactile exploration using a brain-machine-brain interface. Nature 479, 228-231. O'doherty, J.E., Lebedev, M.A., Li, Z., and Nicolelis, M.A. (2012). Virtual active touch using randomly patterned intracortical microstimulation. IEEE Trans Neural Syst Rehabil Eng 20, 85-93. Ray, P.G., Meador, K.J., Smith, J.R., Wheless, J.W., Sittenfeld, M., and Clifton, G.L. (1999). Physiology of perception: cortical stimulation and recording in humans. Neurology 52, 1044-1049. Romo, R., Hernandez, A., Zainos, A., Brody, C.D., and Lemus, L. (2000). Sensing without touching: psychophysical performance based on cortical microstimulation. Neuron 26, 273-278. Romo, R., Hernandez, A., Zainos, A., and Salinas, E. (1998). Somatosensory discrimination based on cortical microstimulation. Nature 392, 387-390. Signorelli, F., Guyotat, J., Mottolese, C., Schneider, F., D'acunzi, G., and Isnard, J. (2004). Intraoperative electrical stimulation mapping as an aid for surgery of intracranial lesions involving motor areas in children. Childs Nerv Syst 20, 420-426. Simeral, J.D., Kim, S.P., Black, M.J., Donoghue, J.P., and Hochberg, L.R. (2011). Neural control of cursor trajectory and click by a human with tetraplegia 1000 days after implant of an intracortical microelectrode array. J Neural Eng 8, 025027. Tsakiris, M., and Haggard, P. (2005). The rubber hand illusion revisited: visuotactile integration and self-attribution. Journal of Experimental Psychology: Human Perception and Performance 31, 80. Wettels, N., Santos, V.J., Johansson, R.S., and Loeb, G.E. (2008). Biomimetic tactile sensor array. Advanced Robotics 22, 829-849. Wyllie, E., Luders, H., Morris, H.H., 3rd, Lesser, R.P., Dinner, D.S., Rothner, A.D., Erenberg, G., Cruse, R., Friedman, D., Hahn, J., and Et Al. (1988). Subdural electrodes in the evaluation for epilepsy surgery in children and adults. Neuropediatrics 19, 80-86.