# AGED-RELATED CHANGES IN CORTICAL CIRCUITS IN HUMANS

> **NIH NIH R01** · WASHINGTON UNIVERSITY · 1993 · $117,658

## Abstract

This application is in response to the program announcement PA-92-07 for
research grants on Neural Systems and Mental, Neurological and Aging
Disorders. The goal of the proposed research is to determine how
functional circuits develop in the human visual cortex and how these
circuits change with advancing age. These questions will be approached by
tracing connections in the aldehyde fixed, postmortem human brain with the
fluorescent dye, DiI. This is a technology which we have first introduced
for studying circuits in the human brain (Burkhalter and Bernardo, 1989).
The study will be focused on connections in the visual cortex, not because
understanding vision or visual disorders are the main interest here, but
because this is the only system in the CNS whose functional architecture
is understood well enough that meaningful structure/function relationships
can be derived, and small alterations in the normal connectivity pattern
can be detected. If successful, it is anticipated that the study will
provide information on a number of important issues. It will show that l)
microcircuits in the human brain can be studied by an experimental method,
2) neuronal circuits develop in a preprogrammed sequence which determines
the maturation of specific functions, 3) cortical connections change
throughout life, and 4) connectivity changes are restricted to systems
that develop late in life and whose development may be strongly influenced
by experience.

The proposal is based on preliminary studies in the human primary visual
cortex (VI) which revealed three principal findings: 1) local connections
within cortical columns develop prenatally, 2) horizontal connections
between columns develop postnatally in a manner that circuits related to
the motion processing pathway develop before circuits the are more closely
associated with form and color analysis, and 3) the laminar organization
of feedback projections to striate cortex is selectively altered in aged
brains. The experiments proposed in this application are focused on
horizontal connections within V1, the second visual area V2 and feedback
projections between V2 and V1. Specifically, we will determine: 1) how
local connections form within V2, 2) whether feedback connections emerge
before forward projections, 3) whether feedback projections are altered in
aged brains and, 4) whether local connections within V1 change over the
span of life. These connections have in common that they allow the
intracortical comparison of distant points of the visual field. This
property is essential for the segmentation of a figure from its surround.
Psychophysical tests indicate that visual tasks that require integration
over large portions of the visual field do not develop until 1 year of age
and deteriorate with advanced age. Thus, it is possible that these changes
are due to alterations of long-range connections within V1, V2 or modified
feedback input from V2 to V1. Similar connections may be important in
other cortica...

## Key facts

- **NIH application ID:** 3123391
- **Project number:** 1R01AG011455-01
- **Recipient organization:** WASHINGTON UNIVERSITY
- **SAM.gov UEI:** L6NFUM28LQM5
- **Principal Investigator:** ANDREAS Hans BURKHALTER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1993
- **Award amount:** $117,658
- **Award type:** 1
- **Project period:** 1993-09-30 → 1996-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3123391

## Citation

> US National Institutes of Health, RePORTER application 3123391, AGED-RELATED CHANGES IN CORTICAL CIRCUITS IN HUMANS (1R01AG011455-01). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3123391. Licensed CC0.

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