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bioRxiv · 10.1101/2025.04.17.649404

All spectral frequencies of neural activity reveal semantic representation in the human anterior ventral temporal cortex

Frisby, S. L.·Halai, A. D.·Cox, C. R.·Clarke, A.·Shimotake, A.·Kikuchi, T.·Kuneida, T.·Arakawa, Y.·Takahashi, R.·Ikeda, A.·Matsumoto, R.·Rogers, T. T.·Lambon Ralph, M. A.
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Abstract

Intracranial electrophysiology offers a unique insight into the nature of information representation in the brain - it can be used to disentangle information encoded in local neuronal activity (gamma and high gamma frequencies) from information encoded via long-range interactions (lower frequencies). We used regularised logistic regression to decode animacy from time-frequency power and phase extracted from electrocorticography (ECoG) grid electrode data recorded on the surface of human vATL. Power in gamma (30 - 60 Hz) and high gamma (60 - 200 Hz) produced reliable decoding, indicating that semantic information is indeed expressed by local populations in vATL. However, power from a wide range of frequencies (4 - 200 Hz) produced significantly higher decoding accuracy and also exhibited the same rapidly-changing dynamic code previously observed when decoding voltage. These findings support the theory that semantic information is encoded by a local vATL "hub" that interacts with distributed cortical "spokes".

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Frisby, S. L., Halai, A. D., Cox, C. R., Clarke, A., Shimotake, A., Kikuchi, T., Kuneida, T., Arakawa, Y., Takahashi, R., Ikeda, A., Matsumoto, R., Rogers, T. T., Lambon Ralph, M. A.. 2025-04-21. All spectral frequencies of neural activity reveal semantic representation in the human anterior ventral temporal cortex. https://doi.org/10.1101/2025.04.17.649404

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