# StretchfMRI: a new technique to study the brainstem correlates of long-latency responses

> **NIH NIH R21** · UNIVERSITY OF DELAWARE · 2020 · $456,666

## Abstract

PROJECT SUMMARY
Spasticity is a common condition after stroke. Clinically, spasticity can be recognized as a velocity-dependent
increase in stretch reflexes, and is one of the primary sources of motor impairment in individuals with chronic
stroke. While a lot of research has addressed how spasticity modulates the gain of short-latency reflexes,
much less is known about the neural pathways that regulate the long-latency responses, a fundamental
component of the human motor control system that is severely affected in patients with post-stroke spasticity.
In this project, we will develp StretchfMRI, a new measurement technique that combines an MRI-compatible
robot with muscle electromyography and with high-resolution functional imaging of the brainstem via fMRI.
StretchfMRI will enable, for the first time in vivo and in human, the measurement of activity of brainstem nuclei
during long-latency responses. In this project, we will use StretchfMRI to establish the direct involvement of
nuclei in the reticular formation in producing a long-latency response.
The technique developed in this project is an important step towards a quantitative understanding of basic
principles of neuromuscular control, and has important applications in assessing neuromotor impairment and
recovery after stroke. StretchfMRI lays the groundwork for establishing causality in cortico-reticular function
associated with LLRs. In future work, we plan to apply StretchfMRI in a patient population to study the neural
correlates underscoring spasticity in patients with stroke-induced motor impairment.

## Key facts

- **NIH application ID:** 9896490
- **Project number:** 1R21NS111310-01A1
- **Recipient organization:** UNIVERSITY OF DELAWARE
- **Principal Investigator:** Fabrizio Sergi
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $456,666
- **Award type:** 1
- **Project period:** 2020-02-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9896490

## Citation

> US National Institutes of Health, RePORTER application 9896490, StretchfMRI: a new technique to study the brainstem correlates of long-latency responses (1R21NS111310-01A1). Retrieved via AI Analytics 2026-05-29 from https://api.ai-analytics.org/grant/nih/9896490. Licensed CC0.

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