Benghanem, S. | bioRxiv Science

bioRxiv2023

The implicit influence of pitch contours and emotional timbre on P300 components in an own-name oddball paradigm

ObjectivePrevious evidence has suggested that paralinguistic features of speech stimuli may influence the characteristics of P300 components when used in clinical evaluation of consciousness. However, it remains unknown what exact acoustic components of speech are influential in such tasks, and whether they are capable of interacting with attentional deployment (as indexed by P300) in an implicit manner. MethodTo study this question, we adapted here an auditory oddball-paradigm used in clinical practice (the "own-name" paradigm), and tested whether systematic transformations of pitch contours (i.e. rising or falling intonation) and emotional timbre (i.e. smiling or rough voices) on the participants names influenced P300 responses in 24 healthy participants. ResultsP300 responses to rising pitch contours were smaller than to falling pitch contours, possibly reflecting an interference of the rising contours with participant attention in the deviant-counting task. No such difference was observed with emotional timbre variations. Conclusion and SignificanceThese results suggest that the cognitive resources involved in pitch contour processing overlap more strongly than timbre with the resources required to count own-name deviants, and that rising pitch contours should be tested prospectively as a way to increase the saliency of consciousness evaluation in unconscious patients.

neuroscience↗

bioRxiv2023

Cortical responses to looming sources are explained away by the auditory periphery

A wealth of behavioral evidence indicate that sounds with increasing intensity (i.e. appear to be looming towards the listener) are processed with increased attentional and physiological resources compared to receding sounds. However, the neurophysiological mechanism responsible for such cognitive amplification remains elusive. Here, we show that the large differences seen between cortical responses to looming and receding sounds are in fact almost entirely explained away by nonlinear encoding at the level of the auditory periphery. We collected EEG mismatch negativity (MMN) data in response to deviant stimuli with both dynamic (looming and receding) and constant level (flat) differences to the standard in the same participants. We then combined a computational model of the auditory periphery with generative EEG methods (temporal response functions, TRFs) to model the single-participant MMN responses to flat deviants, and used them to predict the effect of the same mechanism on looming and receding stimuli. The flat model explained a remarkable 45% variance of the looming response, and 33% of the receding response. This provide striking evidence that MMN responses to looming and receding sounds result from the same cortical mechanism that generate MMN to constant-level deviants: all such differences are the sole consequence of their particular physical morphology getting amplified and integrated by peripheral auditory mechanisms. Thus, not all effects seen cortically proceed from top-down modulations by high-level decision variables, but can rather be performed early and efficiently by feed-forward peripheral mechanisms that evolved precisely to sparing subsequent networks with the necessity to implement such mechanisms.

neuroscience↗