# Optogenetic modulation of inhibition in cat visual cortex

> **NIH NIH R21** · UNIVERSITY OF PENNSYLVANIA · 2021 · $243,542

## Abstract

PROJECT SUMMARY
Image representation in primary visual cortex depends critically on the spatiotemporal pattern of activation of
distributed visual cortical networks. Such activation relies on distribution of contrasts in the visual scene but
also in part in the scaffolding of horizontal connections in supragranular layers 2-3 that connect cortical
columns of similar orientation. For individual visual cortical cells their spatially well defined receptive field (RF)
is not sufficient to explain their visual responses to visual scenes. Indeed, the context of visual stimuli falling
outside of the RF is a critical component of the cell response. Such effects have been called contextual effects,
they depend on the relative properties between the visual stimulus inside and outside of the RF and can be
facilitatory, inhibitory or they can modulate the gain (the slope of the input-output function) of the neuron. A
fundamental impediment to understanding the underlying mechanisms of contextual stimuli is the ability of
manipulating inhibition at the mesoscale of the cortical column. Here, in Aim 1 we propose to implement in the
cat optogenetic approaches that allow to manipulate inhibition with great temporal sensitivity. We will use a
strategy developed recently based on the selective expression of the DLX homeobox gene enhancer mDlx in
cortical GABAergic interneurons of all vertebrate species. We will procure (from the Penn Vector Core) and
inject AAV vectors containing depolarizing (ChR2) and hyperpolarizing (ArchT) opsins under the control of
mDLx. We will verify selective expression with electrophysiology and inmunohistochemistry and will calibrate
the effect of blue and green light on the responses to visual stimuli and current injection of regular and fast
spiking neurons recorded intracellularly in vivo. Work in Aim 1 will be done with the help of Dr. John Wolfe from
the Veterinary School which is an expert in viral approaches for gene therapy. In Aim 2 we will obtain
preliminary data on the role of GABAergic inhibition in surround suppression and gain modulation caused by
contextual stimuli. In addition to strong preliminary data for a future R01 application this project will implement
an approach that will allow addressing over 50 year old questions in a highly visual animal.

## Key facts

- **NIH application ID:** 10110334
- **Project number:** 1R21EY032232-01
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Diego Contreras
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $243,542
- **Award type:** 1
- **Project period:** 2021-03-01 → 2023-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10110334

## Citation

> US National Institutes of Health, RePORTER application 10110334, Optogenetic modulation of inhibition in cat visual cortex (1R21EY032232-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10110334. Licensed CC0.

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