Functional specificity for high-level linguistic processing in the human brain

TLDR

Neuroscientists have long debated whether brain regions are selectively engaged in specific high‑level functions, with language studies showing conflicting neuropsychological dissociations versus neuroimaging overlap with nonlinguistic tasks. The study aims to determine whether individually defined language regions respond to nonlinguistic functions such as arithmetic, working memory, cognitive control, and music. Using fMRI, the authors functionally localized language areas in each participant and tested their activation during arithmetic, working memory, cognitive control, and music tasks. Language regions showed little or no activation to nonlinguistic tasks, supporting a distinct separation between language and other cognitive processes.

Abstract

Neuroscientists have debated for centuries whether some regions of the human brain are selectively engaged in specific high-level mental functions or whether, instead, cognition is implemented in multifunctional brain regions. For the critical case of language, conflicting answers arise from the neuropsychological literature, which features striking dissociations between deficits in linguistic and nonlinguistic abilities, vs. the neuroimaging literature, which has argued for overlap between activations for linguistic and nonlinguistic processes, including arithmetic, domain general abilities like cognitive control, and music. Here, we use functional MRI to define classic language regions functionally in each subject individually and then examine the response of these regions to the nonlinguistic functions most commonly argued to engage these regions: arithmetic, working memory, cognitive control, and music. We find little or no response in language regions to these nonlinguistic functions. These data support a clear distinction between language and other cognitive processes, resolving the prior conflict between the neuropsychological and neuroimaging literatures.