Comparative analyses of Natural Sound-Encoding in Human and Monkey Auditory Cortex

Goal: Cross-species comparison of natural sound processing in Human and Monkey Auditory Cortex (Erb et al., 2019). Experimental design: In order to encode auditory cortical representations of multiple acoustic features in awake macaques and humans, subjects listened to 168 natural sounds (human speech and vocal sounds, animal cries, tool and environmental sounds) in a 3T (macaques) or 7T (humans) fMRI scanner. Design, stimuli and computational modeling approach were identical to the ones presented to human subjects in previous experiments (Moerel et al. 2012, 2013; Santoro et al. 2017). Results: Comparative analyses revealed homologous large-scale topographies for frequency, temporal and spectral modulations. In contrast, model-based decoding of temporal modulations was most accurate for high rates (>30 Hz) in macaques, but at slower rates (~3 Hz) for humans. These slower temporal modulations are relevant for the analysis of speech sounds and may have played a role in the evolution of speech and language.