# Defining the role of the lateral reticular nucleus in skilled forelimb movement

> **NIH NIH F31** · SALK INSTITUTE FOR BIOLOGICAL STUDIES · 2021 · $43,865

## Abstract

Project Summary
Dexterous forelimb tasks vary in their degree of difficulty, but whether someone is performing a life-saving
surgery or reaching for a cup of coffee, the neural mechanisms that underlie these goal-directed movements are
poorly understood. Previous studies have shown that as people perform dexterous forelimb tasks, their limb
movement is constantly being updated as it traverses through space toward a target. This consistent and rapid
updating of forelimb movement suggests that feedback is critical for the success of goal-directed forelimb
movements. However, rapid corrections are performed too quickly to be explained purely by sensory feedback,
because of delays in the transmission of sensory signals from the body to the nervous system. Neuroscientists
have turned to engineering principles of control theory to generate hypotheses regarding the biological elements
of motor control. One theory with considerable empirical evidence is that during forelimb movement, internally
directed efference copies are sent to the cerebellum, so that the cerebellum can make predictions about the
subsequent state of the limb. Generally, evidence for efference copies has been relegated to electrophysiology
and/or behavior studies that demonstrate motor output modulation arriving faster than sensory feedback, but the
characterization of putative neural structures is lacking. The dearth of evidence characterizing putative neural
structures as either sending, processing, or receiving efference copies is due to the difficulties in accessing these
structures. However, the use of molecular-genetic tools in the mouse, to selectively access specific cell types
within a neural structure, has made potential efference copy circuits more accessible. In order to understand
how the cerebellum is using efference copies to generate predictions about subsequent forelimb positions, it is
imperative that the pre-cerebellar processing and organization of efference copies are elucidated. The lateral
reticular nucleus (LRN) is a pre-cerebellar structure entirely composed of neurons that send mossy fiber
projections to the cerebellum. A subset of the input to the LRN comes from the ascending branch of cervical
propriospinal interneurons (PNs). PNs are characterized as spinal interneurons receiving descending motor
commands and sending bifurcating axonal projections; one branch descending to forelimb motor neurons, and
the other branch ascending to the LRN, carrying efference copy information. Therefore, the LRN is an optimal
target for evaluating the role of efference copies in skilled forelimb movement. This proposal attempts to
investigate the functional role of the LRN in skilled forelimb movement by 1) perturbing LRN function during
skilled forelimb movement, and 2) using multi-channel in vivo extracellular recordings to characterize efference
copy organization and processing in the LRN. Beyond dissecting motor control circuits, these findings may help
improve diagnosti...

## Key facts

- **NIH application ID:** 10238147
- **Project number:** 5F31NS115477-03
- **Recipient organization:** SALK INSTITUTE FOR BIOLOGICAL STUDIES
- **Principal Investigator:** Elischa Jamal Sanders
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $43,865
- **Award type:** 5
- **Project period:** 2019-09-16 → 2022-09-15

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10238147

## Citation

> US National Institutes of Health, RePORTER application 10238147, Defining the role of the lateral reticular nucleus in skilled forelimb movement (5F31NS115477-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10238147. Licensed CC0.

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