Models of the brain organization for higher integrative functions derived with electrical stimulation techniques

Exicitatory and disruptive effects of stimulation on human higher integrative functions are reviewed, along with models of brain organization derived from them. Several general properties of stimulation effects on higher integrative functions are identified, including discrete localization, differential localization of several related functions, and individual variability in the exact locations of these effects. A model of the brain organization for language is derived from stimulation effects on several language-related functions. A common peri-Sylvian cortex for motor and language functions is identified in the language dominant hemisphere, including sites common to sequencing of motor movements and comprehension of phonemes that represents an anatomic substrate for the "motor theory of speech perception". This is surrounded by sites related to a cortical short-term verbal memory system, with sites specialized for such language functions as naming or syntax at the interface between these areas. A common "specific alerting response" mechanism for motor and language functions is identified in lateral thalamus of the language dominant hemisphere, a mechanism that may select the appropriate cortical areas for a language function. A similar thalamic mechanism for spatial functions is present in the nondominant hemisphere, as is discrete differential cortical localization of several spatial functions.