Brain organization for language from the perspective of electrical stimulation mapping

TLDR

A model for the organization of language in the adult human brain is derived from electrical stimulation mapping of several language‑related functions during neurosurgical operations under local anesthesia. A common “specific alerting response” mechanism for motor and language functions is identified in the lateral thalamus of the language‑dominant hemisphere, selecting cortical areas appropriate for a particular language function. The study identifies a common peri‑Sylvian cortex for motor and language functions, with adjacent short‑term verbal memory sites and specialized naming/syntax areas, while noting discrete, language‑specific localization in association cortex and substantial individual variability linked to sex, language ability, prior injury, and experience.

Abstract

Abstract A model for the organization of language in the adult humans brain is derived from electrical stimulation mapping of several language-related functions: naming, reading, short-term verbal memory, mimicry of orofacial movements, and phoneme identification during neurosurgical operations under local anesthesia. A common peri-Sylvian cortex for motor and language functions is identified in the language dominant hemisphere, including sites common to sequencing of movements and identification of phonemes that may represent an anatomic substrate for the “motor theory of speech perception.” This is surrounded by sites related to short-term verbal memory, with sites specialized for such language functions as naming or syntax at the interface between these motor and memory areas. Language functions are discretely and differentially localized in association cortex, including some differential localization of the same function, naming, in multiple languages. There is substantial individual variability in the exact location of sites related to a particular function, a variability which can be partly related to the patient's sex and overall language ability and which may depend on prior brain injury and, perhaps subtly, on prior experience. A common “specific alerting response” mechanism for motor and language functions is identified in the lateral thalamus of the language–dominant hemisphere, a mechanism that may select the cortical areas appropriate for a particular language function.