# Optogenetic manipulation of cortical feedback to examine network function and behavior

> **NIH NIH R34** · UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON · 2020 · $453,493

## Abstract

SUMMARY
The brain transforms raw sensory input into perception and cognition, and this transformation relies on
computations performed across neuronal circuits. Fortunately, the anatomy of cortical microcircuits in non-
human primate models is much better understood today than decades ago. Indeed, sensory information travels
in the cerebral cortex along feedforward and feedback pathways. While bottom-up feedforward connections have
been extensively examined over the past several decades, the functional role of feedback projections continues
to remain mysterious. Cortical feedback has been previously examined by reversibly inactivating higher cortex
using a variety of methods, and measuring effects in single neurons in lower cortex. While important, previous
studies modulating cortical feedback using techniques such as pharmacological inactivation, cortical cooling,
electrical microstimulation, or transcranial magnetic stimulation, suffer from several key limitations, including
poor spatial localization and temporal precision, and exclusive focus on single neuron responses. To overcome
these limitations we will use optogenetic and multi-electrode electrophysiological methods in non-human
primates to inactivate cortical feedback in real time based on cell localization, laminar location, and connectivity,
and examine its impact of neural coding and behavior. To this end, we have chosen a major visual pathway
involving primary visual cortex (V1) and mid-level visual cortex (V4). V4 neurons are believed to relay top-down
signals related to behavioral context and attention to area V1 via direct feedback projections. Our working
hypothesis is that feedback connections exhibit functional specificity and increase the population coding
accuracy and communication among cortical neurons to improve behavioral performance. Our proposal will test
the feasibility and validate the use of optogenetic methods in conjunction with multi-electrode recordings of
population activity to directly address several of the desired capabilities for the next generation of neuroscience
tools in non-human primates. We propose a new way to optogenetically control cortical feedback which will lay
the groundwork for an interrogation of large-scale circuits at an unprecedented level of resolution. Thus, our
proposal represents a significant step toward mapping the dynamic activity of relevant brain circuits in real time
and understanding their impact on network coding and behavioral decisions.

## Key facts

- **NIH application ID:** 9984742
- **Project number:** 1R34NS116829-01
- **Recipient organization:** UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
- **Principal Investigator:** VALENTIN DRAGOI
- **Activity code:** R34 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $453,493
- **Award type:** 1
- **Project period:** 2020-05-01 → 2023-09-15

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9984742

## Citation

> US National Institutes of Health, RePORTER application 9984742, Optogenetic manipulation of cortical feedback to examine network function and behavior (1R34NS116829-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9984742. Licensed CC0.

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