# Parallel Pulvinar Pathways

> **NIH NIH R01** · UNIVERSITY OF LOUISVILLE · 2021 · $475,851

## Abstract

PROJECT SUMMARY / ABSTRACT
The concept of parallel pathways that code different aspects of the visual scene has led to many key insights
regarding the functional organization of the visual system. Inspired by this concept, the proposed studies focus
on parallel visual pathways from the retina to the superior colliculus (SC) through the pulvinar nucleus (PUL).
Projections from the SC to the PUL originate from motion-detecting widefield vertical (WFV) cells, and their
synaptic organization defines two distinct PUL subdivisions: one that receives ipsilateral topographic WFV
projections (“specific”), and one that is innervated by bilateral convergent WFV projections (“diffuse”). These two
WFV innervation patterns are correlated with distinct cortical and subcortical connections, as well a variety of
histochemical criteria, suggesting that the tectorecipient PUL may be organized into separate visual movement
processing streams. However, we currently lack a functional framework that allows us to test this hypothesis and
decipher the modular organization of the PUL. We plan to address this gap in knowledge by defining PUL cell
types and synaptic inputs in the context of their functional properties. Our guiding hypothesis is that the PUL is
composed of two distinct modules that coordinate visual perception with body movements or motivational state
to initiate appropriate motor commands. To begin to test this theory, with mice as our animal model, we will use
anatomical intersectional viral vector approaches and in vitro whole cell recordings coupled with dual optogenetic
activation of cortical and WFV synaptic inputs to define circuit mechanisms that can alter firing properties within
each PUL module (Aim 1). We will use in vivo extracellular recordings coupled with optogenetic activation and
silencing of synaptic inputs to determine how circuit interactions within each PUL module adjusts receptive field
properties (Aim 2). A key innovation of our experiments is the ability to identify PUL neuron subtypes by their
unique frequency-dependent responses to optogenetic activation of WFV inputs (“neuron identification via single
input dynamics”). This new method will allow us to link detailed in vitro circuit dissection techniques with in vivo
recording of visual response properties, providing a framework of PUL function that has thus far been elusive.
By comparing two parallel PUL modules, our goal is to understand how visual motion signals are parsed to
initiate appropriate behavioral responses.

## Key facts

- **NIH application ID:** 10145704
- **Project number:** 5R01EY031322-02
- **Recipient organization:** UNIVERSITY OF LOUISVILLE
- **Principal Investigator:** MARTHA E BICKFORD
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $475,851
- **Award type:** 5
- **Project period:** 2020-05-01 → 2024-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10145704

## Citation

> US National Institutes of Health, RePORTER application 10145704, Parallel Pulvinar Pathways (5R01EY031322-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10145704. Licensed CC0.

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