# Comparative Neuroanatomy at single-neuron resolution

> **NIH NIH R34** · ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI · 2021 · $758,394

## Abstract

Project summary
Although single neurons occasionally project to a single downstream target, it is more often the case that their
axons collateralize and project to multiple distinct anatomical areas. This feature of neuroanatomy has been
appreciated for over 100 years and is theorized to be critical to coordinating brain-wide states. Despite this,
collateral projections have largely been overlooked in contemporary neuroscience. This is because mapping
collateral projections has practically been beyond the reach of empirical investigation, especially in non-human
primates where single neurons can project over wide areas. To surmount these issues, our goal here is the
comprehensive development of a sequencing-based approach that will allow us to reveal the patterns of
connections of single neurons in non-human primates using Multiplexed Analysis of Projections by Sequencing
(MAPseq). This approach allows the full collateral projections of potentially thousands of individual neurons to
be mapped in a single animal. The first step towards our goal is to validate a sequencing-based connectomic
approach in macaque monkeys that has previously been developed and validated in mice (Aim1). Then, once
validated we will determine the local and long-range connections of individual neurons in one part of the limbic
system in macaques, the amygdala. Our primary focus here is to determine the patterns of collateral projections
from amygdala to the frontal cortex (FC) as these have been implicated in the pathophysiology of many
psychiatric disorders. With the method for discerning the multiple projection targets of single neurons in the
macaque brain in hand we will then compare the patterns that we see in amygdala to those in mice (Aim 2). We
hypothesize that through the expansion and differentiation of FC in non-human primates, single amygdala
neurons in non-human primates will be many more collateral projections compared to mice. In summary, when
successful, our approach has the potential to fully discern the projection profiles of single neurons in non-human
primates. This will enable novel insights into the neuroanatomical networks present in non-human primates,
provide a powerful new tool for investigating comparative anatomy and aid interpretation of functional studies
that target the amygdala in both non-human primates and mice.

## Key facts

- **NIH application ID:** 10216577
- **Project number:** 1R34NS122050-01
- **Recipient organization:** ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
- **Principal Investigator:** Roger L Clem
- **Activity code:** R34 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $758,394
- **Award type:** 1
- **Project period:** 2021-04-15 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10216577

## Citation

> US National Institutes of Health, RePORTER application 10216577, Comparative Neuroanatomy at single-neuron resolution (1R34NS122050-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10216577. Licensed CC0.

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