Computational model of neuronal recruitment during ICMS for restoring somatosensation in the human somatosensory cortex

Objective Intuitively providing touch feedback from artificial hands to users with sensory loss remains a challenge. Although localized fingertip sensations can be evoked via intracortical microstimulation (ICMS), feedback is generally optimized using psychometric tasks rather than mimicking the cortical response to touch. Approach We created an anatomically-informed and participant-specific model of the human somatosensory cortex (S1) region with an implanted microelectrode array (MEA). We performed simultaneous stimulation-and-recording from the study participant S1 region to characterize cortical responses elicited by single ICMS pulses. Pulses were delivered to a set of pre-selected electrodes mapped to tactile receptive fields. We next performed a 2D (i.e., in the plane of the MEA probe tips) current source density (CSD) analysis of recorded cortical responses to inform cortical network model parameters on how ICMS activates neurons and lateral synaptic connections in the area of the S1 sampled by MEA electrodes. Using information from planar CSD profiles obtained from ground truth data, we reconstructed lateral connections in the S1 model needed to produce the desired responses to single ICMS pulses. The effect of multiple ICMS was then simulated in the biologically realistic cortical model and the results were validated against ground truth cortical responses from the study participant. Main results A high-resolution cortical network model, calibrated to produce the known cortical responses to single ICMS pulses delivered to individual electrodes, predicted with a reasonable accuracy the cortical response to ICMS pulses delivered simultaneously to multiple electrodes. Significance These preliminary results suggest that high-resolution biologically realistic cortical network models can potentially be reliable predictors of cortical response to a given pattern of ICMS presentations and therefore useful in designing biomimetic stimulation patterns. ### Competing Interest Statement William S. Anderson reports relationships with 1) Longeviti NeuroSolutions that includes: board membership, 2) Globus Medical that includes: consulting or advisory, and 3) iota Biosciences that includes: consulting or advisory. Matthew S. Fifer reports a relationship with Mind-X that includes: consulting or advisory. ### Clinical Trial NCT03161067 ### Funding Statement This work was supported by ARO grant W911NF-20-1-0183 and the Johns Hopkins SOM Discovery Fund Program Challenge Awards. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was conducted under an Investigational Device Exemption (170010) by the Food and Drug Administration for the purpose of evaluating bilateral sensory and motor capabilities of microelectrode array implants. The study protocol is registered as a clinical trial ([NCT03161067][1]) and was approved by the Food and Drug Administration, the Johns Hopkins Institutional Review Board, and the U.S. Army Medical Research and Development Command Human Research Protection Office. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT03161067&atom=%2Fmedrxiv%2Fearly%2F2023%2F06%2F29%2F2023.06.22.23291761.atom