Specialization for Language in the Human Brain
The human language system evolved against the backdrop of other, evolutionarily older systems. How does the language system fit with the rest of our mind and brain? Does it rely on specialized mechanisms, or does it instead make use of machinery that we use to perform other complex tasks? Using data from brain imaging investigations and studies of patients with brain damage, I will argue that a set of brain regions in the adult human brain is specialized for high-level language processing. When probed with functional MRI, these regions – in the frontal and temporal lobes of the left hemisphere – respond robustly during language comprehension and production, but show little or no response when we engage in arithmetic processing, hold information in working memory, inhibit irrelevant information, listen to music, or perceive meaningful non-linguistic representations. Consistent with these functionally selective responses, damage to the language system leaves most non-linguistic cognitive abilities largely intact. I argue that this fronto-temporal network emerges over the course of development as we acquire language knowledge. In the adult brain, this system stores our linguistic knowledge representations and uses these representations to interpret and generate new utterances. Ongoing work aims to characterize i) the precise computations that the regions of the language system perform, as well as ii) this system’s interactions with other large-scale brain networks, needed to achieve uniquely human cognition.