Evidence for evolutionary divergence in temporal integration windows between human and monkey auditory cortex

The cortical representation of the temporal dimension of sound in the primate auditory cortex remains an open question. In this work, we review studies that investigated the brain basis for the processing of acoustic time windows in humans, macaques and marmosets that employ functional magnetic resonance imaging and neurophysiological recordings. We identify the functional anatomy of response patterns to temporal integration for each study, to arrive at a representative organization in humans and non-human primates (NHP). A synthesis of prior studies identifies a certain level of commonality for temporal processing in primates. Surprisingly, however, our analysis revealed that while both humans and NHPs process shorter time-windows in postero-medial areas and longer time-windows in non-primary lateral areas, macaque neurobiological responses in primary auditory cortex appear to favor shorter temporal timescales than human primary auditory cortex. This difference in neurobiological sensitivity is in line with behavioural sensitivities in these species. This review and analysis results raise the possibility of evolutionary specialization of the human cortex relative to nonhuman primates, potentially for the processing of speech which requires sensitivity to longer timescales.