Dynamic Norm-Based Coding of Vocal Identity in the Primate Auditory Cortex

Voice identity recognition is vital for social communication, yet its neural encoding mechanisms remain unclear. We investigated whether neurons in the anterior temporal voice area (aTVA) of macaques use norm-based coding (NBC), similar to face encoding in vision. Using synthetic vocalizations morphed along identity trajectories, we found that early neuronal responses (100 to 150 ms) exhibited V-shaped tuning, with minimal activity for the average voice and increased responses for extreme identities. Later (200 ms), a distinct rebound in activity for the average voice emerged, driven by a unique subpopulation. These results highlight a dynamic, multi-stage encoding strategy, extending NBC principles to auditory processing.