# Parallel pathways in visual cortex: functional connectivity of output pathways from area V1 to area V2

> **NIH NIH R01** · UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH · 2020 · $381,250

## Abstract

PROJECT SUMMARY
Hierarchical feedforward (FF) models of the visual system have provided a foundation for most theories of
visual processing over the past 40 years. It is problematic that these models have relied on probabilistic
representations of FF connectivity between visual areas, partly because we lack information about the wiring
principles and functional organization of FF connections, even between the earliest visual areas V1 and V2,
which have been studied for decades. Our goal is to uncover the rules of anatomical and functional
connectivity for V1 output pathways to V2 to anatomically-constrain FF models of vision. This information is
crucial to understand how V1 and V2 reorganize retinal signals into processing streams, and how V1 output
pathways contribute to generating the receptive field (RF) properties and functional maps in V2. In primates,
parallel pathways from V1 project to distinct V2 cytochrome-oxidase (CO) stripes [thick (Tk), thin (Tn) and
pale (Pl)]. It is unknown whether the local connections of V1 output cells, and their V1 inputs integrate
information across parallel streams or maintain within-stream segregation. It is also debated whether distinct
V1 and V2 CO compartments show specialized or diverse visual response properties, partly because it has been
difficult to record from identified V1 output cells. During prior funding period, we found that the local intra-V1
connectivity of V1 cells projecting to Tk stripes shows within-stream segregation. It is, thus, important to
extend these studies to V1 cells projecting to Tn and Pl stripes. To address this goal, we will label these cells
using viral vectors, reconstruct them through whole V1 and V2 blocks rendered optically transparent, and align
them to CO and functional maps of V1 and V2 (Aim1). Using viral-based monosynaptic circuit tracing
combined with CO-staining and optical imaging (OI) of functional maps, we will test the hypothesis that the V1
and V2 inputs to V1 cells projecting to distinct V2 stripes are also stream specific, arising from the same CO and
functional compartments as the V1 output cells that they contact (Aim2). We will also test the hypothesis of
functional segregation in the monosynaptic projections from V1 to V2 stripes, by characterizing the visual
responses of optogenetically-identified V1 cells projecting to distinct stripes (Aim3). Finally, it is unknown
how V1 inputs are combined within local V2 columns in each stripe; this information is crucial to understand
how V1 inputs contribute to generating the more complex RF properties of V2 cells. We will address this
question both anatomically and functionally (Aim4). In SubAim4a, we will determine how V1 inputs to
single V2 columns are distributed over the V1 functional maps, by combining OI of functional maps with
injections of retrograde tracers in V2. In SubAim4b we will characterize the population RF of V1 inputs to a
local V2 column, using simultaneous array recordings in V1 and V2 and ...

## Key facts

- **NIH application ID:** 9846211
- **Project number:** 5R01EY019743-10
- **Recipient organization:** UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH
- **Principal Investigator:** Alessandra Angelucci
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $381,250
- **Award type:** 5
- **Project period:** 2009-08-01 → 2021-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9846211

## Citation

> US National Institutes of Health, RePORTER application 9846211, Parallel pathways in visual cortex: functional connectivity of output pathways from area V1 to area V2 (5R01EY019743-10). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9846211. Licensed CC0.

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