# Mechanisms of electrical stimulation of a canonical motor microcircuit

> **NIH NIH R01** · NORTHWESTERN UNIVERSITY · 2021 · $508,868

## Abstract

The neural circuitry of the spinal cord has a unique, repetitive structure that forms an especially promising
target for control via electrical stimulation. Furthermore, this structure allows the essential circuits for
generation of movements to be preserved below the level of a spinal cord injury (SCI). Electrical stimulation
techniques targeted at these remaining sensorimotor circuits are thus becoming highly promising therapies.
These approaches usually take advantage of another basic aspect of spinal anatomy, that all sensory axons
enter the cord via a highly accessible location, its dorsal surface. Thus dorsal electrical stimulation (DES) via
surface electrodes provides effective activation of sensory axons without the need for penetrating electrodes.
The spinal connections of these sensory axons mediate potent effects on spinal motor circuits. In this
proposal, we examine the neural mechanisms of DES to clearly define its potential for controlling motor output
and to create a rational basis for improving its therapeutic implementation. The basic goal of DES is to
recreate key functions of the descending inputs from the brain to the cord, which are of course damaged or lost
in SCI. Thus a fundamental question is, how well can DES of sensory axons replicate the effects of
descending inputs on spinal neurons. To address this question, we focus on the canonical motor microcircuit
(CMM), which comprises a single set of antagonist motor pools and the local circuits that process their sensory
feedback about muscle length and velocity. The group Ia axons conveying this information are large and likely
to be more sensitive to DES than any other type of sensory input. We apply multiple techniques, including
intra-axonal recording in sensory axons, extracellular recording of interneurons and voltage clamp in
motoneurons. Our Aims are to map the distribution of excitatory and inhibitory synaptic input generated in the
CMM by DES, identify the roles of the intrinsic electrical properties of spinal neurons in processing these
inputs, assess whether DES activation of sensory axons interferes with their normal function and probe the
mechanism that underlie the stability and focus of the CMM when driven by DES or normal sensory inputs.
The proposed studies will provide a fundamental underpinning for DES of the spinal cord and are likely to
identify new opportunities for improvement its therapeutic effectiveness.

## Key facts

- **NIH application ID:** 10247044
- **Project number:** 5R01NS109552-04
- **Recipient organization:** NORTHWESTERN UNIVERSITY
- **Principal Investigator:** Charles Heckman
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $508,868
- **Award type:** 5
- **Project period:** 2018-09-30 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10247044

## Citation

> US National Institutes of Health, RePORTER application 10247044, Mechanisms of electrical stimulation of a canonical motor microcircuit (5R01NS109552-04). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10247044. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*