Biology subjects

Trapeau, R.

Publications and source records attributed to Trapeau, R..

5 recordsLinked to original sources

bioRxiv2025

Neural pathways of voice perception: a comparative dMRI study between humans and macaques.

The processing of vocal stimuli in the human brain involves multiple regions that are selectively tuned to voice information. Similarly, voice-sensitive areas have been identified in macaques, suggesting a common neural mechanism across species. However, the structural connectivity underlying voice perception in both humans and macaques remains poorly understood. In this study, we investigate the structural connectivity of voice-sensitive regions in 4 humans and 3 macaques using awake functional MRI and diffusion MRI techniques. Our findings reveal that while humans and macaques differ in the anatomical organization of projections from the anterior Temporal Voice Area (aTVA), the organization of projections from the primary auditory cortex (A1) is nearly identical. Our results also demonstrate distinct connectivity patterns between the vocal areas of the two species, as well as an opposite pattern of lateralization of aTVA-A1 connectivity in humans and macaques. These results enhance our understanding of the neural circuits involved in voice perception and provide valuable insights into the comparative neurobiology of vocal communication.

neuroscience↗

bioRxiv2025

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

Recognition of vocal identity is essential for primate social behavior, yet the neural mechanisms supporting this ability remain poorly understood. Cognitive models suggest that the brain may represent identity based on an average voice prototype. Here, we tested this hypothesis by recording spiking activity from single neurons in an fMRI-localized voice-selective region of the anterior temporal lobe in two rhesus macaques. Using synthetic "coo" calls systematically morphed along identity trajectories from "anti-voices" to caricatures, we found that early neuronal responses ([~]100 ms post-stimulus) exhibited robust V-shaped tuning to distance from the average voice. This pattern reflects an energy-efficient representational strategy in which neural activity increases with identity distinctiveness, also applied to face stimuli. Unexpectedly, a distinct subpopulation of neurons showed a delayed ([~]200 ms) rebound response selectively enhanced for the average voice. These findings reveal two temporally dissociable mechanisms for vocal identity encoding in primate auditory cortex, suggesting that the brain emphasizes both distinctiveness and prototypicality to support efficient and flexible voice recognition. Significance statementRecognizing who is speaking is fundamental to primate social life, yet how the brain encodes vocal identity remains poorly understood. Cognitive theories suggest that the brain may represent identity relative to an internal "average" voice, but direct neural evidence has been lacking. Here, we recorded single-neuron activity in a voice-selective brain region of rhesus macaques and found two distinct coding strategies: one that increases neural activity with identity distinctiveness, and another that selectively enhances the average voice itself. These results reveal dual mechanisms for vocal identity encoding in the primate brain, highlighting how the brain balances flexibility and efficiency in social communication.

neuroscience↗

bioRxiv2024

Voice identity invariance by anterior temporal lobe neurons

The ability to recognize speakers by their voice despite acoustical variation plays a significant role in primate social interactions. While neurons in the macaque anterior temporal lobe (ATL) show invariance to face viewpoint, whether they also encode abstract representations of caller identity is not known. Here we show that neurons in the voice-selective ATL of two macaques show invariance to voice identity via dynamic representations that minimize within-caller neuronal distances while maintaining distinct neural trajectories for different individuals. A small proportion of highly identity-selective neurons plays a central role although less selective neurons are also informative. Our findings provide a neural basis for voice identity recognition in primates and highlight the ATL as a key hub for integrating perceptual voice features into higher-level identity representations.

neuroscience↗

bioRxiv2024

Reconstructing Voice Identity from Noninvasive Auditory Cortex Recordings

The cerebral processing of voice information is known to engage, in human as well as non-human primates, "temporal voice areas" (TVAs) that respond preferentially to conspecific vocalizations. However, how voice information is represented by neuronal populations in these areas, particularly speaker identity information, remains poorly understood. Here, we used a deep neural network (DNN) to generate a high-level, small-dimension representational space for voice identity--the voice latent space (VLS)--and examined its linear relation with cerebral activity via encoding, representational similarity, and decoding analyses. We find that the VLS maps onto fMRI measures of cerebral activity in response to tens of thousands of voice stimuli from hundreds of different speaker identities and better accounts for the representational geometry for speaker identity in the TVAs than in A1. Moreover, the VLS allowed TVA-based reconstructions of voice stimuli that preserved essential aspects of speaker identity as assessed by both machine classifiers and human listeners. These results indicate that the DNN-derived VLS provides high-level representations of voice identity information in the TVAs.

neuroscience↗

bioRxiv2018

Perceptual grouping in the cocktail party: contributions of voice-feature continuity

Cocktail parties pose a difficult yet solvable problem for the auditory system. Previous work has shown that the cocktail-party problem is considerably easier when all sounds in the target stream are spoken by the same talker (the voice-continuity benefit). The present study investigated the contributions of two of the most salient voice features -- glottal-pulse rate (GPR) and vocal-tract length (VTL) -- to the voice-continuity benefit. Twenty young, normal-hearing listeners participated in two experiments. On each trial, listeners heard concurrent sequences of spoken digits from three different spatial locations and reported the digits coming from a target location. Critically, across conditions, GPR and VTL either remained constant or varied across target digits. Additionally, across experiments, the target location either remained constant (Experiment 1) or varied (Experiment 2) within a trial. In Experiment 1, listeners benefited from continuity in either voice feature, but VTL continuity was more helpful than GPR continuity. In Experiment 2, spatial discontinuity greatly hindered listeners abilities to exploit continuity in GPR and VTL. The present results suggest that selective attention benefits from continuity in target voice features, and that VTL and GPR play different roles for perceptual grouping and stream segregation in the cocktail party.

neuroscience↗