Sunday, May 18, 2025
5/18/2025
Determining face representations within and transformations between temporal and prefrontal cortex - PROJECT SUMMARY/ABSTRACT Circuits of the visual system transform patterns of light impinging on the retina into an understanding of objects and their behavioral significance, achieving robustness and versatility currently not matched by even the most advanced computational vision models. Much of this high-level information extraction is thought to occur in the ventral stream, a pathway of interconnected brain regions which include areas for the processing of faces. The prefrontal cortex, typically associated with cognitive functions, receives highly-processed visual output from the ventral stream and also feeds signals back into it, resulting in a recurrently connected visual-cognitive loop. To address these fundamental questions, this proposal uses face stimuli and the face-selective patches that process them, including one in the anterior temporal cortex (aTC) in the ventral stream and the other in ventrolateral prefrontal cortex (vlPFC). The central hypothesis to be tested is that aTC and vlPFC contain qualitatively different face representations, one emphasizing physical properties, the other meaningful categories, and that this difference shapes feed-forward and feed-back processing between them. The work proposed here leverages the advantages of a small, lissencephalic brain, the use of multi-regional high-density electrophysiology, and mesoscale calcium imaging to determine the spatial organization of face codes with single-cell resolution. Aim 1 will determine how face features are represented in aTC and vlPFC through simultaneous, translaminar recordings using Neuropixels probes. It will test the specific hypothesis that aTC represents faces in a feature- specific and physically accurate manner, while vlPFC represents faces holistically and as exemplars of meaningful social categories. Aim 2 will determine the spatial organization of face representations in vlPFC through mesoscale multiphoton calcium recordings of thousands of cells simultaneously. It will test the specific hypothesis that multiple abstract face-related categories are represented within vlPFC in a spatially segregated manner. Aim 3 will determine the role of vlPFC feedback signals on aTC face representation using dual probe recordings to test the hypothesis that robustness to ambiguous inputs results from recurrent interaction between temporal and frontal circuits and reflects category selectivity. This project will make use of modern advances in neural recording technology to address questions about the precise orchestration of brain activity across regions, whose disruption is associated with debilitating dysfunctions such as schizophrenia. It will develop a model system and approaches for mechanistic dissections of high-level perceptual and cognitive functions and contribute to our understanding of the specific neural circuitry underlying face perception and social cognition that is known to be perturbed in neuropsychiatric disorders such as prosopagnosia, frontotemporal dementia, and autism spectrum disorders.
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