Auditory sequence processing reveals evolutionarily conserved regions of frontal cortex in macaques and humans

Abstract

An evolutionary account of human language as a neurobiological system must distinguish between human-unique neurocognitive processes supporting language and evolutionarily conserved, domain-general processes that can be traced back to our primate ancestors. Neuroimaging studies across species may determine whether candidate neural processes are supported by homologous, functionally conserved brain areas or by different neurobiological substrates. Here we use functional magnetic resonance imaging in Rhesus macaques and humans to examine the brain regions involved in processing the ordering relationships between auditory nonsense words in rule-based sequences. We find that key regions in the human ventral frontal and opercular cortex have functional counterparts in the monkey brain. These regions are also known to be associated with initial stages of human syntactic processing. This study raises the possibility that certain ventral frontal neural systems, which play a significant role in language function in modern humans, originally evolved to support domain-general abilities involved in sequence processing.

Abstract

This study uses functional magnetic resonance imaging in humans and monkeys to show similar ventral frontal and opercular cortical responses when processing sequences of auditory nonsense words. The study indicates that this frontal region is involved in evaluating the order of incoming sounds in a sequence, a process that may be conserved in primates.