Action Planning and Affective States Within the Auditory Peripersonal Space.

Fast reaction to approaching stimuli is vital for survival as for sounds entering the individual auditory Peripersonal Space (PPS). Closer sounds have found to provoke higher motor cortex activation particularly for highly arousing sounds, showing the close relationship for perceptual components of the sounds and motor preparation. Here Normal Hearing (NH) individuals and Cochlear Implanted (CI) individuals have been compared in their ability to recognize evaluate and react to affective stimuli entering the PPS. Twenty (seven females) NH and ten (three females) CI participants were asked to react to Positive (P), Negative (Ne), Neutral, (Nu) affective sounds virtually ending at five different distances from their body by performing fast arms flexion. Pre-motor Reaction Times (pm-RTs) were detected via EMG from postural muscles to measure action anticipation at different sound stopping distances; furthermore, the same sounds were evaluated for their level of valence and arousal perceived. Both groups showed the ability to localize the sound distances but only NH individuals modulated their pm-RTs based on the sound distance. Interestingly when the sound was not carrying affective components, as for Nu sounds, both NH and CI individuals triggered the promptest pre-motor reaction time (shorter pm-RT) when compared to P and N sounds. Only NH individuals modulated sound distance with the level of sound arousal, while sounds valence was similarly perceived by both NH and CI individuals. These results underline the role of emotional states in action preparation and describe the specific perceptual components necessary to properly react to approaching sounds within peripersonal space.