# Understanding the Microcircuits in Monkey Sensory Cortices: a Connectomic Approach

> **NIH NIH SC3** · YORK COLLEGE · 2024 · $118,680

## Abstract

Abstract
 The development of serial confocal and electron-microscopy (EM), and automated image
segmentation have allowed us to elucidate some of the structural details of the cortical circuit at the
cellular and synaptic level. This information is critical because there is a close link between the
morphological properties of circuits in different brain areas and their function. It is broadly accepted that
the canonical microcircuit of the cortex is a repeating motif across cortex. Once the structure and
function in the local motif is understood this could be applied across all of cortex. However, recently it
has been shown that there are major laminar, areal and species differences that need to be taken into
account by this model. Another important feature of the canonical circuit in sensory areas is that the
initial thalamocortical (TC) driving input to layer 4 in cortex, which was presumed to be weak, needs to
be massively amplified to obtain the observed rates of spiking. However, recent studies have shown
that the weak TC assumption, has underestimated the TC strength by 2-4 times. I hypothesis that,
although the canonical circuit may provide general framework for cortical circuit functioning, diverse
sensory brain areas have major laminar differences in their neuronal and synaptic distributions. These
differences will, in turn, reflect the diverse processing roles and capabilities of the brain areas. To test
this hypothesis I will examine three primary sensory areas in macaque monkey cortex using Focused
Ion Beam/Scanning EM to determine detailed synaptic connectivity, using high-resolution confocal
microscopy to provide large scale determination of specific synaptic connectivity, and using mid-
resolution confocal microscopy to determine global cell type distributions in specific brain regions. If, as
I hypothesize, there are major quantitative differences between areas that will reflect their diverse
processing roles and capabilities, this will call for a refinement of the concept of the canonical circuit.
These quantitative results are important to build realistic population based spiking models of cortex that
can reproduce many of the detailed functional characteristics that are found in the brain. They are also
important because understanding the basic cortical organization of the normal brain is essential, as it
provides the standard against which it can be judged which processes can be seen to be altered or
damaged in disorders that affect the cerebral cortex. Additionally, an important part of this project is my
professional development as a PI. As such, I have established a research enhancement plan to
increase my research scholarship and publications, with the final goal of acquiring non-SCORE
research support.

## Key facts

- **NIH application ID:** 10755327
- **Project number:** 5SC3NS127766-03
- **Recipient organization:** YORK COLLEGE
- **Principal Investigator:** Virginia Garcia-Marin
- **Activity code:** SC3 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $118,680
- **Award type:** 5
- **Project period:** 2022-01-15 → 2025-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10755327

## Citation

> US National Institutes of Health, RePORTER application 10755327, Understanding the Microcircuits in Monkey Sensory Cortices: a Connectomic Approach (5SC3NS127766-03). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10755327. Licensed CC0.

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