# Functional Organization of the Visual System

> **NIH NIH R01** · VANDERBILT UNIVERSITY · 2020 · $385,397

## Abstract

SUMMARY
Our previous research on monkeys and prosimian galagos used half-second trains of electrical pulses
delivered via microelectrodes to define eight small regions (domains) in posterior parietal cortex (PPC) where
stimulation produced different complex movements. Functionally matched sets of domains were also found in
motor (M1) and premotor (PMC) cortex that were additional parts of parallel parietal-frontal networks. In our
study to date, we have described some of the connections of domains with each other in the same region, and
across regions, with feedforward projections from PPC being focused on functionally matched PMC and M1
domains. Using optical imaging, we found that stimulating PPC domains activated matching PMC and M1
domains. Furthermore, lesioning or cooling M1 domains blocked the effects of stimulation matched, but not
mismatched PPC domains. We propose to further determine the organization and functions of these domains
and networks by determining their connections with other regions of cortex and subcortical structures. In
addition, we will determine whether connections between domains are mainly excitatory or suppressive by
selectively labeling neurons that terminate on inhibitory neurons, and by optically imaging cortical activation
patterns during electrical stimulation. Also we will electrically stimulate sets of two domains at once to see if the
movements produced reflect competition or cooperation. We predict that the motor effects of stimulating pairs
of matching domains in PPC and M1 at the same time will be additive, resulting in faster and more extensive
movements, and that stimulating mismatched pairs of domains will result in mutual or alternating suppression,
the dominance of one domain action on the other, a blending of two movements, or two separate movements
depending on the movements of each member of the pair. Finally, we will stimulate multiple sites within the
reaching domain to see if an internal map of reach locations exist, and in a similar manner see if the looking
domains have a map of visual targets. Our methods of investigation include electrical microstimulation of
domains, optical imaging of intrinsic signals of evoked activity during electrical stimulation of domains or
sensory input to domains, and the tracing brain connections with a number of tracers, including modified rabies
virus and adeno-associated virus. The results are expected to produce a new and greatly expanded
understanding of the functional organization of parietal-frontal networks in primates, how functional domains
interact with each other, how they are guided by sensory information, and how they mediate different classes
of behaviors. The connection patterns of domains with other areas of cortex and subcortical structures will
reveal the more extended networks, and differences in connections of functionally matched domains will
suggest their specialized roles. These studies will help us to evaluate our proposal that the prima...

## Key facts

- **NIH application ID:** 9885025
- **Project number:** 2R01EY002686-42
- **Recipient organization:** VANDERBILT UNIVERSITY
- **Principal Investigator:** JON H KAAS
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $385,397
- **Award type:** 2
- **Project period:** 1978-06-01 → 2024-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9885025

## Citation

> US National Institutes of Health, RePORTER application 9885025, Functional Organization of the Visual System (2R01EY002686-42). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9885025. Licensed CC0.

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