Identifying Tactile Evidence Accumulation-Based Choice-Related Neural Activity in Mouse PPC-RL
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Kim, Ashley
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Abstract
Decision-making requires the integration of sensory information and its transformation into behaviorally relevant choices. The posterior parietal cortex (PPC) has been implicated in evidence accumulation and choice-related processing across multiple modalities, but the role of its somatosensory subdivision, the rostrolateral area (RL), remains unclear. This study functionally characterized RL activity during a tactile two-alternative forced choice (2AFC) task in mice to evaluate its contribution to somatosensory decision-making. Using high-density electrophysiological recordings, we analyzed neural firing rates during stimulus presentation, behavioral response, and across varying levels of trial difficulty. We identified distinct subpopulations of neurons that showed choice selectivity, trial difficulty sensitivity, and temporal dynamics linked to decision execution. Notably, many choice-selective neurons exhibited asymmetric tuning and differential sensitivity to subtle versus broad difficulty contrasts, suggesting RL encodes graded decision variables. Additionally, the majority of choice-selective neurons were classified as fast-spiking (FS), implicating inhibitory interneurons in decision-related processing. These findings provide functional evidence that RL is not solely a sensory region but participates in the transformation of sensory input into action. By linking anatomical connectivity with functional responses, this work advances our understanding of RL as a critical node in tactile decision-making circuits.
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Undergraduate Research Option Thesis