# Cell-Type-Specific Mechanisms of Contextual Modulation in the Visual Cortex

> **NIH NIH F32** · UNIVERSITY OF CALIFORNIA BERKELEY · 2022 · $67,582

## Abstract

Project Summary
Natural vision relies on segmenting spatially distributed stimuli within the visual environment and encoding them
according to spatial context. For neurons in the primary visual cortex (V1), their response depends on the
variance of visual stimuli between the classical receptive field and the surround. This property known as
“surround modulation” powerfully influences sensory coding but its magnitude and sign flexibly depends on the
degree of similarity of features, such as orientation, between the center and surround. The specific V1 circuits
that explain orientation dependence of surround modulation are largely unknown. This project aims to elucidate
the synaptic and circuit mechanisms of orientation dependence of surround suppression through an all-in-vivo
approach combining two-photon (2P) targeted whole-cell electrophysiology, single-cell resolution 2P holographic
optogenetics to map synaptic connectivity, and 2P calcium imaging to record population activity. The hypothesis
of this project is that the orientation dependence of surround suppression depends on orientation-tuned
somatostatin (SST) interneuron-mediated lateral inhibition via co-tuned excitation from the surround. As SST
interneurons respond strongly to large iso-oriented but not cross-oriented visual stimulation where the center
and surround are orthogonally oriented, this suggests that the tuning of SST interneurons to spatial context is
key to feature dependence of surround suppression. To test the core hypothesis of tuning-specific connectivity
driving feature-preference across retinotopic space, the aims in this project will first examine the synaptic drive
in SST interneurons that gives rise to their selectivity for relative orientation of the center and surround, and next
use a novel combinatory in vivo 2p calcium imaging/2p holographic optogenetic approach to test whether
orientation-specific connectivity supports the physiological tuning of V1 SST neurons and pyramidal cells to
contextual stimuli. These experiments will not only provide a mechanistic understanding of aspects of visual
computation, but also demonstrate conceptual and technical advances that may be applied broadly to other key
questions in neuroscience.

## Key facts

- **NIH application ID:** 10465675
- **Project number:** 1F32EY034022-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA BERKELEY
- **Principal Investigator:** Masato Sadahiro
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $67,582
- **Award type:** 1
- **Project period:** 2022-04-01 → 2025-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10465675

## Citation

> US National Institutes of Health, RePORTER application 10465675, Cell-Type-Specific Mechanisms of Contextual Modulation in the Visual Cortex (1F32EY034022-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10465675. Licensed CC0.

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