# Targeting and Stimulating Cortical Area 3a to Restore Proprioception

> **NIH NIH R21** · CLEVELAND CLINIC LERNER COM-CWRU · 2024 · $201,250

## Abstract

Project Summary/Abstract:
The larger goal of this study is to gain foundational knowledge and demonstrate the feasibility of
restoring percepts of arm muscle force using intracortical microstimulation (ICMS) in cortical
area 3a. Restoring this specific sensory percept is particularly important to paralyzed individuals
that use brain-controlled functional electrical stimulation (FES) of their peripheral nerves to
restore arm movements by thought after spinal cord injury. Appropriate balancing of antagonist
muscle forces in this population is critical for maintaining limb stability and minimizing muscle
fatigue and battery drain. In Aim 1, we will use primate imaging and surgical planning software
to implant custom chronic microwire electrode arrays deep into the elbow region of the central
sulcus of two Rhesus macaques (four hemispheres total) to target the difficult-to-reach
somatosensory area 3a. Area 3a receives a range of proprioceptive signals from Golgi tendon
organs (conveys muscle force) and muscle spindle fibers (conveys muscle length and change in
length) and should provide muscle-specific percepts most directly relevant to optimizing FES
arm movement restoration. However, most of what is known about 3a proprioceptive encoding
has been collected from acute recordings. In this study, we will use chronic microelectrode
recordings and a range of active and passive sensorimotor tasks across days to more fully
characterize 3a encoding. These data will then be used to quantify the relative function and
spatial distribution of these different sensory encoding characteristics on the spatial scale
relevant to restoring these sensations via ICMS. In the second aim, we will use a novel force
tracking game to test the animals' ability to perceive ICMS of force-dominant electrode locations
as an increase in muscle force. This game is designed to prevent the animals from just learning
to respond to some unnatural `sensation' for a reward and will verify that the subjects are
actually utilizing the force percepts in their motor planning. Finally, we will conduct these tests
using a range of stimulus parameters to quantify the magnitude of the force percepts as a
function of stimulation parameters.

## Key facts

- **NIH application ID:** 10839921
- **Project number:** 5R21NS128685-02
- **Recipient organization:** CLEVELAND CLINIC LERNER COM-CWRU
- **Principal Investigator:** Dawn Marie Taylor
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $201,250
- **Award type:** 5
- **Project period:** 2023-05-15 → 2026-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10839921

## Citation

> US National Institutes of Health, RePORTER application 10839921, Targeting and Stimulating Cortical Area 3a to Restore Proprioception (5R21NS128685-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10839921. Licensed CC0.

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