Topic > The role of Broca's area in language processing

Language is a complex and multifaceted brain function, supported by a distributed circuit of interconnected brain areas (Moritz-Gasser & Duffau, 2009). Until the 1970s, research on the organization of language production and comprehension was mainly based on the analysis of behavioral deficits in patients with brain lesions. Using this technique the classical neurological model of language processing was developed by Broca (1861) and Wernicke (1874), later extended by Lichtheim (1885). It involved two brain regions involved in language production and comprehension: Broca's area in the inferior frontal gyrus (IFG) and Wernicke's area in the posterior superior temporal gyrus (pSTG), respectively. He suggested that Broca's area stores motor representations of words while Wernicke's area contains information about what words sound like and what their meanings are. While the first neurological model of language broke away from the ideas of phrenology and offered a new framework for neuropsychological research, it had numerous shortcomings. It was unable to account for the fact that people with Broca's aphasia (also known as nonfluent, expressive, or agrammatic aphasia) had a variety of seemingly different impairments or that some people with focal damage to Broca's area showed no aphasia agrammatic (Bookheimer, 2002). Only with the advancement of neuroimaging techniques was it established that this is due to functional specification. Specific regions in the inferior frontal gyrus are responsible for specific linguistic skills: speech articulation, understanding complex syntactic structures, producing sentences, naming objects, etc. (Bookheimer, 2002). Notably, not all of these functions are affective...... half of the article ......del believes that LIFG has a role in unifying semantic, syntactic and phonological processing (Hagoort, 2005) Mapping of linguistic functions on the identification of cortical regions has been a complicated task considering the use of different terminologies by different reports: some of them define cortical regions in terms of Broadmann areas (e.g. BA44/45), others use an anatomical nomenclature based on the gyri (e.g. pars opercularis/triangularis of the IFG) Different terminologies cause confusion as the regions do not necessarily occupy the same space. The overlapping functions of different IFG areas suggest that it may be better to move away from the paradigm of the modular representation of language in the brain and focus on uncovering the network of interconnected modules between different parts of the brain responsible for specific aspects of language production..