Neural manifolds carry reactivation of phonetic representations during semantic processing.
bioRxiv
; 2024 Jan 21.
Article
in En
| MEDLINE
| ID: mdl-37961305
ABSTRACT
Traditional models of speech perception posit that neural activity encodes speech through a hierarchy of cognitive processes, from low-level representations of acoustic and phonetic features to high-level semantic encoding. Yet it remains unknown how neural representations are transformed across levels of the speech hierarchy. Here, we analyzed unique microelectrode array recordings of neuronal spiking activity from the human left anterior superior temporal gyrus, a brain region at the interface between phonetic and semantic speech processing, during a semantic categorization task and natural speech perception. We identified distinct neural manifolds for semantic and phonetic features, with a functional separation of the corresponding low-dimensional trajectories. Moreover, phonetic and semantic representations were encoded concurrently and reflected in power increases in the beta and low-gamma local field potentials, suggesting top-down predictive and bottom-up cumulative processes. Our results are the first to demonstrate mechanisms for hierarchical speech transformations that are specific to neuronal population dynamics.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
BioRxiv
Year:
2024
Document type:
Article
Affiliation country:
Suiza