# Computational roles of inhibition in human action control

> **NIH NIH R01** · UNIVERSITY OF OREGON · 2024 · $79,679

## Abstract

ABSTRACT
Classic neurocognitive models of cortico-basal ganglia circuits imply excitatory signals drive, and inhibitory
signals suppress, behavioral output. However, inhibition can support other computations. Important research on
animal motor systems and human sensory systems has shown inhibition shapes the gain and tuning properties
of neural populations. Compelling evidence suggests these same two computations support action preparation
in the human motor system. The overall objectives of this application are to establish roles for gain modulation
and tuning within the human motor system during action preparation and to evaluate to what extent these
computations relate to the neurochemical capacity for inhibition. The long-term goals of this work are to
characterize physiological and neurochemical contributions to the neural computations underlying human action
control and to understand how disease-related disruption of these mechanisms contributes to behavioral
impairments. Accordingly, the proposed experiments will test the central hypothesis that gain and tuning within
the human corticospinal pathway change dynamically during the preparation of actions and relate to inhibitory
neurotransmitter availability in motor cortex. The first specific aim of this application is to test the hypothesis that
gain within the human motor system increases during action preparation to facilitate the execution of a selected
action. The second specific aim is to test the hypothesis that spatial tuning of motor representations sharpens
during action preparation. Sharper tuning of motor representations is expected to promote more fine-grained
control by facilitating the selective recruitment of muscles involved in a prepared action. Whereas Aim 1
examines a computational mechanism for facilitating the execution of a selected action, Aim 2 examines a
computational mechanism for selecting actions from a pool of neighboring and overlapping representations. We
will use non-invasive brain stimulation to examine the patterns of excitability within a given muscle (Aim 1) and
across a group of muscles (Aim 2) to detect changes in gain and tuning, respectively, during behavioral task
performance. The third specific aim of this application is to explore relationships between gain, tuning, and local
availability of the inhibitory neurotransmitter gamma-amino butyric acid (GABA) in the cortex. Individual
differences will be examined to test whether the availability of local GABA correlates with the magnitude of gain
and tuning changes. We hypothesize individuals with more GABA in motor cortex will exhibit greater increases
in gain and sharper tuning during action preparation. The proposed work is innovative because the roles of gain
and tuning within the human motor system are crucially understudied and their links to neurochemical content
are completely unexplored. This research is significant because the results could change our interpretation of
the roles of inhibition ...

## Key facts

- **NIH application ID:** 10991762
- **Project number:** 3R01NS123115-03S1
- **Recipient organization:** UNIVERSITY OF OREGON
- **Principal Investigator:** Ian Greenhouse
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $79,679
- **Award type:** 3
- **Project period:** 2022-04-01 → 2027-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10991762

## Citation

> US National Institutes of Health, RePORTER application 10991762, Computational roles of inhibition in human action control (3R01NS123115-03S1). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10991762. Licensed CC0.

---

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