Structured sequence processing, language evolution and the primate brain

Christopher I. Petkov,

Laboratory of Comparative Neuropsychology, Newcastle University

Many animals, nonhuman primates included, are not thought to be able to combine their vocalizations into structured sequences. Nonetheless, it remains possible that certain animals are able to recognize rule-based sequences of varying levels of complexity, such as those generated by ‘artificial grammars’. Understanding the extent of nonhuman primate abilities in these regards could clarify the neurobiological correspondences and differences that trace a path to human language. In this talk I will first describe behavioral results from studies that we have conducted with humans and two species of monkeys, macaques and marmosets, representing different primate evolutionary lineages. Then I will describe fMRI results on macaque brain regions that are involved in these processes, including how these results compare to fMRI findings in humans. I conclude by overviewing macaque EEG and neuronal recording results, which are providing insights on the time-course of neuronal responses associated with sequence processing in the human and monkey brain. Overall, our results reveal that non-human primates appear to possess an evolutionarily conserved perisylvian network involved in the processing of structured auditory input. Alongside the commonalities, there are also intriguing cross-species differences that inform us on how the human brain differentiated to support language.