# The functional role of corticogeniculate feedback in vision

> **NIH NIH R01** · UNIVERSITY OF ROCHESTER · 2020 · $385,000

## Abstract

Abstract
Corticothalamic circuits linking primary sensory cortex with primary sensory thalamus in the feedback direction
are ubiquitous across sensory modalities and mammalian species and are ideally positioned to regulate the
flow of sensory signals from periphery to cortex. However, the functional role of these circuits in sensory
perception remains a fundamental mystery in neuroscience. In the visual system, corticogeniculate neurons
provide the majority of inputs onto neurons in the lateral geniculate nucleus (LGN), however receptive fields of
LGN neurons closely resemble their retinal inputs and not their corticogeniculate inputs. Partly because
corticogeniculate influence over LGN activity appears to be modulatory rather than driving, the functional role
of corticogeniculate feedback in vision has been difficult to characterize. The goal of this proposal is to employ
optogenetics – an emerging technology that allows for selective and reversible manipulation of neurons in
intact animals – to examine the structural organization of corticogeniculate circuits and to elucidate their
functional contributions toward vision. The three Specific Aims of this proposal address three critical features of
corticogeniculate circuits: 1) the structure-function relationships among corticogeniculate circuits; 2) the types
of information conveyed by corticogeniculate neurons to LGN neurons; and 3) how corticogeniculate signals
impact LGN neuronal activity. A series of nine experiments, three in each Aim, examining corticogeniculate
morphology, physiology, functional connectivity, receptive field transformations and impact on LGN activity, will
systematically test two alternative hypotheses that corticogeniculate feedback is functionally homogenous
versus functionally stream-specific. To accomplish the experiments under each of the three Specific Aims,
corticogeniculate neurons in ferrets are selectively infected with virus encoding channelrhodopsin2 and
mCherry and optogenetically activated during simultaneous multi-electrode array recordings of LGN and visual
cortical neuronal responses to drifting gratings and white noise stimuli. Preliminary results suggest that
optogenetic activation of corticogeniculate neurons is sufficient to drive changes in LGN responses to visual
stimuli. In revealing the structural and functional organization of corticogeniculate circuits, the information they
convey to the LGN and their impact on LGN activity, results of the proposed experiments will reveal whether
corticogeniculate circuits serve as global gain modulators that synchronize activity across LGN cell types or
selectively prioritize information about specific visual features through stream-specific modulations.
Furthermore, insights gained about corticogeniculate circuit function could generalize across corticothalamic
pathways throughout the sensory system and inform understanding of sensory circuit disruptions associated
with sensory-processing deficits observed in ...

## Key facts

- **NIH application ID:** 9928939
- **Project number:** 5R01EY025219-06
- **Recipient organization:** UNIVERSITY OF ROCHESTER
- **Principal Investigator:** Farran Briggs
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $385,000
- **Award type:** 5
- **Project period:** 2016-05-01 → 2021-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9928939

## Citation

> US National Institutes of Health, RePORTER application 9928939, The functional role of corticogeniculate feedback in vision (5R01EY025219-06). Retrieved via AI Analytics 2026-07-28 from https://api.ai-analytics.org/grant/nih/9928939. Licensed CC0.

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