Biophysical modeling reveals how recording geometry shapes representations of cortical activity
- 1Nathan Kline Institute for Psychiatric Research
Abstract
Extracellular electrophysiological recordings reflect both the organization of neural activity and the geometry through which that activity is sampled. Here, we used biophysical modeling and experimental recordings from the macaque auditory cortex to determine how cortical activity is transformed across neural sources, extracellular signals, and recording geometries. In a biophysically detailed thalamocortical model, four separately instantiated cortical-column conditions spanning graded thalamic recruitment exhibited a graded response hierarchy across local field potential, current-source density, and multiunit activity, despite signal-dependent differences in the contributions of cortical neuronal populations. We then arranged independently simulated cortical columns into controlled spatial configurations and sampled the same underlying sources using virtual linear laminar and Directional and Scalable (DiSc) electrode arrays. The linear geometry primarily represented variation along cortical depth, whereas DiSc additionally represented circumferential variation associated with lateral source organization, demonstrating that recording geometry determines which spatial dimensions of common underlying activity are represented in extracellular measurements. Experimental recordings obtained with the corresponding geometries were consistent with these model-derived predictions: broadband-noise responses exhibited spatial organization shared across tone-evoked responses in both multidimensional DiSc maps and laminar profiles, despite substantial variation in frequency-dependent response magnitude across penetrations. Together, these results show that extracellular measurements represent an interaction between biological source organization and recording geometry. Biophysical forward modeling therefore provides a framework for determining which features of underlying circuit organization remain identifiable after extracellular sampling and for relating neural-interface design to the dimensions of cortical activity accessible experimentally.
Related
- Self-supervised representations reveal the genetic architecture of human cortical folding
- Connectome-based biophysical modeling of a figure-ground discrimination circuit
- Biophysical modeling of excitation/inhibition imbalance in Alzheimer's disease
- Distinct gradients of cortical architecture capture visual representations and behavior across the lifespan
- Highly resolved representations of dynamic haptic inputs in non-primary sensory cortical neuron representations
BibTeX
@misc{diazmontiel2026biophysical,
title = {{Biophysical modeling reveals how recording geometry shapes representations of cortical activity}},
author = {A. A. Diaz-Montiel and J. A. Willis and G. Unal and A. M. Abrego and Y. Kajikawa and J. C. Mosher and C. E. Schroeder and S. Dura-Bernal and J. P. Seymour and S. A. Neymotin},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.17.752414},
url = {https://www.biorxiv.org/content/10.64898/2026.09.17.752414v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Biophysical modeling reveals how recording geometry shapes representations of cortical activity
AU - A. A. Diaz-Montiel
AU - J. A. Willis
AU - G. Unal
AU - A. M. Abrego
AU - Y. Kajikawa
AU - J. C. Mosher
AU - C. E. Schroeder
AU - S. Dura-Bernal
AU - J. P. Seymour
AU - S. A. Neymotin
PY - 2026
DA - 2026/09/17
PB - bioRxiv
DO - 10.64898/2026.09.17.752414
UR - https://www.biorxiv.org/content/10.64898/2026.09.17.752414v1
AB - Extracellular electrophysiological recordings reflect both the organization of neural activity and the geometry through which that activity is sampled. Here, we used biophysical modeling and experimental recordings from the macaque auditory cortex to determine how cortical activity is transformed across neural sources, extracellular signals, and recording geometries. In a biophysically detailed thalamocortical model, four separately instantiated cortical-column conditions spanning graded thalamic recruitment exhibited a graded response hierarchy across local field potential, current-source density, and multiunit activity, despite signal-dependent differences in the contributions of cortical neuronal populations. We then arranged independently simulated cortical columns into controlled spatial configurations and sampled the same underlying sources using virtual linear laminar and Directional and Scalable (DiSc) electrode arrays. The linear geometry primarily represented variation along cortical depth, whereas DiSc additionally represented circumferential variation associated with lateral source organization, demonstrating that recording geometry determines which spatial dimensions of common underlying activity are represented in extracellular measurements. Experimental recordings obtained with the corresponding geometries were consistent with these model-derived predictions: broadband-noise responses exhibited spatial organization shared across tone-evoked responses in both multidimensional DiSc maps and laminar profiles, despite substantial variation in frequency-dependent response magnitude across penetrations. Together, these results show that extracellular measurements represent an interaction between biological source organization and recording geometry. Biophysical forward modeling therefore provides a framework for determining which features of underlying circuit organization remain identifiable after extracellular sampling and for relating neural-interface design to the dimensions of cortical activity accessible experimentally.
ER -