# Visual Stimulus Coding and Metabolic Demand in Macaque Primary Visual Cortex

> **NIH NIH F32** · UNIVERSITY OF ALABAMA AT BIRMINGHAM · 2021 · $58,403

## Abstract

Project Summary/Abstract
 The relationships between neural response properties, their anatomical underpinnings, and the
metabolic profile of neural tissue are key issues that define the normal functional architecture of the
cerebral cortex. Understanding how these different systems are organized and work together is
fundamental to neuroscientific research. Recent advances in optical imaging of cerebral activity have
made it possible to record activity of both neuronal and metabolic dynamics simultaneously.
 In primate primary visual cortex (V1), the relationships between neuronal orientation and color
selectivity have been related to distribution of the metabolic enzyme cytochrome oxidase (CO) and
vascular dynamics. The pattern of CO distribution in macaque V1 is a defining characteristic of this brain
area. In V1, metabolic demand varies locally and by layer, as evident by diffuse CO-dense patches of
cortex surrounded by less dense CO regions in layer 2/3. The distribution of CO in neurons has also been
shown to be related to the density and organization of the vasculature which supplies the cortical tissue
with nutrients and metabolites.
 The long-established idea of how these systems interact suggests that strongly orientation tuned
neurons reside in only CO interpatch regions while unoriented color tuned neurons reside exclusively in
CO patches. However, recent research has shown that such a functional segregation is unlikely. Because
earlier techniques failed to measure cone-specific and orientation-specific responses in the same cells
and relate them to the CO pattern, new techniques—such as 2-photon imaging—are needed to develop an
accurate picture of the functional organization of V1. In addition, the vasculature surrounding tuned
neurons has been shown to have its own tuning through changes in vessel dilation and contraction, and
therefore are expected to be related to the CO pattern if neural sensitivity to specific stimuli is locally
organized in V1.
 The goal of this proposal is to characterize the interaction of neuronal visual stimulus tuning, CO
compartment identity, and vascular dynamics in primate V1. In Aim 1 we will use multiphoton calcium
imaging to record orientation and cone specific selectivity in V1 and align the imaged regions with
histological sections of CO staining to determine how neurons with different response profiles are
distributed among CO patch or interpatch regions. In Aim 2 we will examine whether vascular dynamics
are related to cone-specific orientation selectivity and CO compartment identity. The findings of this
study will give us comprehensive information on the basic organization of the V1 and fundamentally alter
our understand of visual processing.

## Key facts

- **NIH application ID:** 10266764
- **Project number:** 5F32EY030725-02
- **Recipient organization:** UNIVERSITY OF ALABAMA AT BIRMINGHAM
- **Principal Investigator:** Michael Savage
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $58,403
- **Award type:** 5
- **Project period:** 2020-04-01 → 2022-02-01

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10266764

## Citation

> US National Institutes of Health, RePORTER application 10266764, Visual Stimulus Coding and Metabolic Demand in Macaque Primary Visual Cortex (5F32EY030725-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10266764. Licensed CC0.

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