# Organization of neural coding and plasticity in L2/3 of mouse S1 cortex

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA BERKELEY · 2024 · $451,119

## Abstract

Summary
Non-topographic, intermixed representations (salt-and-pepper maps) of sensory information are common in
cerebral cortex, but how neural coding and plasticity are organized within them is unclear. We propose that
salt-and-pepper maps contain distinct pyramidal (PYR) subnetworks with differential roles in coding stability
and flexibility (including learning and attentional modulation). To test this, we study the whisker map in layer
2/3 of mouse somatosensory cortex (S1), where PYR cells tuned for the columnar whisker (CW) and for non-
columnar (non-CW) whiskers are intermixed in each column. We recently discovered that non-CW tuned cells
show marked tuning instability across days, while CW-tuned cells have stable tuning. This reveals that the
L2/3 salt-and-pepper map has two components: a stable columnar map of CW-tuned cells, intermixed with
non-CW tuned cells that are unstably tuned and have little columnar topography. We propose that CW- and
non-CW tuned cells are distinct PYR subcircuits with different roles in coding and plasticity.
 This is a novel model of S1 circuit function. We predict that the CW network provides coding stability,
while non-CW cells are the primary site for plasticity and learning. Based on preliminary data, we hypothesize
that tuning instability in non-CW cells is internally driven, and acts to sample novel sensory codes which may
then be stabilized by experience or reward. This is a novel hypothesis for how sensory maps balance stability
and plasticity—by segregating these functions in different subcircuits. In Aim 1, we use longitudinal 2-photon
calcium imaging to understand the nature and origins of tuning instability, and to test whether experience or
reinforcement stabilizes whisker tuning. In Aim 2, we evaluate whether CW and non-CW networks represent
distinct functional networks with different sensory coding and plasticity properties. We test our central
hypothesis that non-CW cells are the primary locus of sensory plasticity and learning within the map.
 Aim 3 asks how attention modulates neural coding within intermixed maps. We developed a selective
attention task in which mice use history-dependent cues to guide attention to a specific whisker to improve
detection performance. Mice show robust spatial attention to cued whiskers. Attention lasts ~10 sec and is
driven by recent pairing of whisker stimuli with reward. Preliminary data show that attention enhances
whisker-evoked activity of PYR cells encoding the attended whisker in S1. This establishes S1 as a powerful
site to study cortical mechanisms of attention. We will use 2-photon imaging and Neuropixels recording to
study how attention modulates sensory coding in S1, including measuring the size and CW- or non-CW
network specificity of the attentional spotlight. In a major effort, we use imaging and optogenetics to identify
the control circuits for attention in S1, with initial focus on VIP interneurons.
 Together, these studies will reveal how pla...

## Key facts

- **NIH application ID:** 10811790
- **Project number:** 5R01NS092367-09
- **Recipient organization:** UNIVERSITY OF CALIFORNIA BERKELEY
- **Principal Investigator:** Daniel Feldman
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $451,119
- **Award type:** 5
- **Project period:** 2023-04-01 → 2028-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10811790

## Citation

> US National Institutes of Health, RePORTER application 10811790, Organization of neural coding and plasticity in L2/3 of mouse S1 cortex (5R01NS092367-09). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10811790. Licensed CC0.

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