Biology subjects

Jacob, S. N.

Publications and source records attributed to Jacob, S. N..

3 recordsLinked to original sources

bioRxiv2024

Parcellation of the primate prefrontal cortex by cognitive control operations

Modular organization, the division of the cerebral cortex into functionally distinct subregions, is well established in the primate sensorimotor cortex, but debated in the cognitive association cortex, including the prefrontal cortex (PFC). Here, we obtained microelectrode recordings with broad spatial coverage from the lateral PFC of two rhesus monkeys performing a working memory task with distractors. We found that neighboring electrodes shared task-related oscillatory neural dynamics that were stable across recording sessions and formed spatially continuous, mesoscale clusters that also segregated by local and long-range frontoparietal connectivity, spiking activity, involvement in working memory processing stages and influence on behavioral accuracy. Remarkably, the degree of parcellation reflected the animals individual mnemonic abilities and strategies. Our findings support functional organization of the PFC by cognitive control operations rather than by the type of processed information, indicating that modularity may be a fundamental architectural principle across the primate cortex.

neuroscience↗

bioRxiv2023

The neurocellular implementation of representational geometry in primate prefrontal cortex

Modern neuroscience has seen the rise of a population-doctrine that represents cognitive variables using geometrical structures in activity space. Representational geometry does not, however, account for how individual neurons implement these representations. Here, leveraging the principle of sparse coding, we present a framework to dissect representational geometry into biologically interpretable components that retain links to single neurons. Applied to extracellular recordings from the primate prefrontal cortex in a working memory task with interference, the identified components revealed disentangled and sequential memory representations including the recovery of memory content after distraction, signals hidden to conventional analyses. Each component was contributed by small subpopulations of neurons with distinct electrophysiological properties and response dynamics. Modelling showed that such sparse implementations are supported by recurrently connected circuits as in prefrontal cortex. The perspective of neuronal implementation links representational geometries to their cellular constituents, providing mechanistic insights into how neural systems encode and process information.

neuroscience↗

bioRxiv2022

Human acute microelectrode array recordings with broad cortical access, single-unit resolution and parallel behavioral monitoring

Human single-unit studies currently rely on neurosurgical procedures that provide only limited brain coverage and on recording devices that do not integrate easily into established surgical routines. Here, we report reliable and robust acute multi-channel recordings with broad cortical access using planar microelectrode arrays (MEA) implanted intracortically in awake brain surgery. We provide a comprehensive characterization of extracellular neuronal activity acquired intraoperatively in tumor patients with large open craniotomies. MEA implantation was fast, safe and yielded high-quality signals at the microcircuit, local field potential level, and at the cellular, single-unit level. Recording from parietal association cortex, a region previously unexplored in human single-unit studies, we demonstrate applications on these complementary spatial scales and describe travelling waves of oscillatory activity as well as single-neuron and neuronal population responses during numerical cognition including operations with uniquely human number symbols. Intraoperative MEA recordings are practicable and can be scaled up to explore cellular and microcircuit mechanisms of a wide range of human brain functions.

neuroscience↗