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Layer-specific dissection of frontal feedback circuits in active visual processing

Award Number: R21EY039032
ORGANIZATION: NATIONAL EYE INSTITUTE
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 07/01/2026
PERIOD OF PERFORMANCE END DATE: 06/30/2028

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Layer-specific dissection of frontal feedback circuits in active visual processing - Project Summary Hierarchical processing in the primate brain depends on layer-specific feedforward and feedback circuits that mediate communication across distributed cortical areas. Classical models posit that feedforward projections arise from superficial layers and feedback from deep layers, each with distinct roles in sensory transmission and contextual modulation. However, anatomical studies show that feedback from frontal areas such as the frontal eye field (FEF) to posterior visual cortex (area MT) arises from both superficial and deep layers, suggesting parallel feedback pathways with potentially dissociable functions. The contributions of these pathways to active visual behavior remain unknown. This R21 proposal aims to develop and validate novel methods for targeting and silencing laminar-specific frontal feedback pathways in the primate brain, focusing on the FEF→MT projection. We hypothesize that superficial-layer FEF neurons transmit top-down attentional signals, while deep- layer neurons convey motor efference copy to support predictive coding. Full testing of this hypothesis will be pursued in a future R01; here, we will establish two critical tools to enable that work. We leverage innovative technologies in the common marmoset, including: (1) ultrasound-guided fetal intraventricular viral injection (FIVI) for layer-specific gene delivery; (2) retrograde adeno-associated virus injection into MT for projection-specific targeting; (3) bidirectional optogenetic tools for rapid, reversible neuron control; and (4) laminar electrophysiology in MT during visual behavior. Aim 1 will test the functional role of FEF→MT feedback in pre-saccadic attention, saccadic suppression, and remapping. Optogenetic silencing of FEF→MT neurons at distinct pre-saccadic timepoints will reveal the temporal dynamics of frontal feedback during behavior. Aim 2 will validate the specificity and efficacy of layer-specific targeting of FEF→MT projection neurons using FIVI combined with retrograde viral delivery and laminar recordings. This project establishes a powerful framework for probing circuit-level mechanisms of top-down control in primates, laying the groundwork for future studies of cortical computation and its disruption in neuropsychiatric disorders.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2026 ( Subtotal = $415,875 )
2026	2026	UNIVERSITY OF ROCHESTER	910 GENESEE ST	ROCHESTER	NY	14611	MONROE	USA	Vision Research	000	1	7/1/2026	NEW	$415,875
														Subtotal = $415,875

Grand Total All Awards = $415,875

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Layer-specific dissection of frontal feedback circuits in active visual processing

Award Number: R21EY039032

ORGANIZATION: NATIONAL EYE INSTITUTE

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 07/01/2026

PERIOD OF PERFORMANCE END DATE: 06/30/2028

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