# Functional Synaptic Architecture of Visual Cortex

> **NIH NIH R01** · MAX PLANCK FLORIDA CORPORATION · 2020 · $482,500

## Abstract

Project Summary/Abstract
Understanding how circuits in visual cortex transform the information supplied by different populations of
retinal ganglion cells into orderly representations of the visual world remains a fundamental challenge that
limits our progress in elucidating the cortical mechanisms of visual perception. While progress has been
substantial, a major gap in our understanding of the cortical transform remains because the transform ultimately
resides in the input/output functions of individual neurons, and the functional synaptic architecture that allows
individual neurons to integrate inputs from diverse sources to produce coherent sensory representations remains
largely unknown. The experiments in this proposal address this challenge by employing state of the art in vivo
functional imaging techniques to probe the functional synaptic architecture of columnar representations in layer
2/3 of primary visual cortex (V1). Recent work from this laboratory has provided new insights into how the
information derived from ON- and OFF- center retinal ganglion cells is transformed into orderly columnar maps
of orientation, visual space, and absolute spatial phase in layer 2/3 of the tree shrew, a species that has a close
phylogenetic relation to primates and a well-developed functional columnar architecture. The goal of the
proposed experiments is to elucidate the functional synaptic architecture of this cortical transform by using in
vivo 2-photon imaging of calcium signals to visualize the response properties of identified synaptic inputs
within the dendritic fields of individual layer 2/3 pyramidal neurons. Two specific aims are proposed, one
focused on elucidating the synaptic architecture of the receptive field center and the other, the synaptic
architecture of the receptive field surround. These experiments will provide the first detailed test of the
functional specificity of synaptic inputs that a neuron receives and how these inputs compare with the properties
of the receptive field center and surround. Equally important, these experiments will determine the spatial
organization of functionally defined synaptic inputs within the dendritic tree, providing the first direct test of the
hypothesis that dendritic topology contributes significantly to somatic receptive field structure. By taking
advantage of a novel model system, and the latest advances in in vivo imaging and genetically encoded calcium
sensors, these experiments will yield a host of novel insights into the functional synaptic architecture of the
cortical transform that will enlighten our understanding of mechanisms of cortical function and their alteration
in injury and disease.

## Key facts

- **NIH application ID:** 9897637
- **Project number:** 5R01EY006821-31
- **Recipient organization:** MAX PLANCK FLORIDA CORPORATION
- **Principal Investigator:** DAVID FITZPATRICK
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $482,500
- **Award type:** 5
- **Project period:** 1987-09-01 → 2022-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9897637

## Citation

> US National Institutes of Health, RePORTER application 9897637, Functional Synaptic Architecture of Visual Cortex (5R01EY006821-31). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9897637. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*