# Cortical circuit mechanisms of visual shape processing

> **NIH NIH R01** · COLUMBIA UNIVERSITY HEALTH SCIENCES · 2024 · $427,015

## Abstract

PROJECT SUMMARY
Humans and other primates rely on using visual shape information to identify and interact with objects in the
world. The goal of this project is to gain mechanistic insights into how the primate cerebral cortex processes
visual shape information. Cortical area V4 is an ideal locus for these mechanistic studies because many V4
neurons are tuned for visual shape, showing preferences for convex or concave segments along an object's
bounding contour. This tuning for visual shape is presumed to be a foundation for behaviorally relevant object
representations, but we know little about its mechanistic implementation. Chiefly, we do not know which cortical
pathways and cell types are responsible for generating this tuning in V4 neurons. In this project, we will begin
to fill these knowledge gaps by employing viral vector-mediated, cell type-specific optogenetics in monkeys. In
Aim 1, we will ask: How does visual shape processing in V4 depend on feedforward excitatory signals from
earlier cortical areas V1 and V2? The experiments related to this aim will test the hypothesis that feedforward
excitation from area V2 is the dominant factor in dictating the shape tuning of V4 neurons. In Aim 2, we will
ask: How does visual shape processing in V4 depend on local inhibitory signals within this area? The
experiments related to this aim will test the hypothesis that inhibitory neurons are tuned for shape, and that
local inhibition sharpens the tuning of excitatory neurons. Accomplishing these aims will provide critical first
insights into the role of feedforward excitation and local inhibition in visual shape processing. A deeper
understanding of these cortical circuit mechanisms in primates has the potential to transform the way in which
we treat disorders of form vision such as visual agnosia. Advancing optogenetic techniques for neural circuit
dissection in monkeys will also facilitate the investigation of other complex brain functions that are specific to
primates: an imperative for advancing basic science and human medicine.

## Key facts

- **NIH application ID:** 10747372
- **Project number:** 5R01EY032190-04
- **Recipient organization:** COLUMBIA UNIVERSITY HEALTH SCIENCES
- **Principal Investigator:** Yasmine El-Shamayleh
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $427,015
- **Award type:** 5
- **Project period:** 2021-01-01 → 2025-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10747372

## Citation

> US National Institutes of Health, RePORTER application 10747372, Cortical circuit mechanisms of visual shape processing (5R01EY032190-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10747372. Licensed CC0.

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