# Role of top-down feedback in visual perception

> **NIH NIH R00** · UNIVERSITY OF HOUSTON · 2024 · $248,963

## Abstract

PROJECT SUMMARY
Visual information travels along feedforward connections from the primary visual cortex (V1) through a hierarchy
of cortical areas. In turn, the visual cortex receives a dense network of feedback (FB) connections from higher-
order cortical areas. FB connections have been implicated in several forms of top-down influences, such as
attention, expectation, and context dependent visual processing, but the specific contributions of FB connections
to visual perception have remained mysterious. The goal of this proposal is to uncover how FB from the second
visual cortical area (V2) to primary visual cortex (V1) affects visual perception and neural response properties of
V1 neurons in primates. This goal will be achieved by targeting optogenetic inactivation to the axons of FB
connections in awake behaving marmosets performing visual tasks. Candidate’s previous studies in
anesthetized marmosets have shown that V2 FB affects receptive field (RF) size, surround suppression and
response gain of V1 neurons. To test how these neural level effects manifest in perception, FB connections
projecting from V2 to V1 will be optogenetically inactivated in awake marmoset monkeys performing visual tasks.
The proposed project builds directly upon the candidate’s existing training in optogenetics, electrophysiology and
psychophysics, but provides significant new training in using awake behaving marmosets. Advances in genome
editing tools and success in transgene germline transmission in marmosets have positioned the marmoset as
an important model system for neuroscience. Therefore, new training in awake behaving marmoset research will
provide a strong foundation for transitioning to independence, and a skill set that will position the candidate
ahead of the competition in the use of genetically engineered marmosets in neuroscience.

## Key facts

- **NIH application ID:** 10828768
- **Project number:** 5R00EY029374-05
- **Recipient organization:** UNIVERSITY OF HOUSTON
- **Principal Investigator:** Lauri Nurminen
- **Activity code:** R00 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $248,963
- **Award type:** 5
- **Project period:** 2018-09-30 → 2026-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10828768

## Citation

> US National Institutes of Health, RePORTER application 10828768, Role of top-down feedback in visual perception (5R00EY029374-05). Retrieved via AI Analytics 2026-06-14 from https://api.ai-analytics.org/grant/nih/10828768. Licensed CC0.

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