The error of Broca: From the traditional localizationist concept to a connectomal anatomy of human brain

Publication date: Available online 14 April 2017 Source:Journal of Chemical Neuroanatomy Author(s): Hugues Duffau Neurology, especially aphasiology, was mainly built on behavioral-structural correlations (“lesion method”). In this setting, Broca's area has been considered as the “speech area”; moreover, this observation led to localizationism. However, advances in brain mapping techniques, as functional neuroimaging and direct electrical stimulation in patients undergoing awake surgery for gliomas, has resulted in a paradigmatic shift regarding models of neural architecture. In fact, the brain is organized in distributed complex networks underpinning sensorimotor, visuospatial, language, cognitive and emotional functions. In this connectomal workframe, cerebral processing is not conceived as the sum of segregated subfunctions, but results from the integration and potentiation of parallel (even if partially overlapped) subcircuits. Such a networking model, taking into account cortical and subcortical anatomic constraints, explains interindividual variability in physiology and after brain damage, particularly in aphasiology − e.g. double dissociations during electrostimulations, as comprehension versus naming disorders, semantic versus phonemic paraphasias, or syntactic disturbances versus anomia. This dynamic organization mediated by the well-synchronized functioning of delocalized groups of interconnected neurons (rather than by discrete centers) also explains th...
Source: Journal of Chemical Neuroanatomy - Category: Neuroscience Source Type: research