Broca's Region: Novel Organizational Principles and Multiple Receptor Mapping |
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Authors: | Katrin Amunts Marianne Lenzen Angela D Friederici Axel Schleicher Patricia Morosan Nicola Palomero-Gallagher Karl Zilles |
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Institution: | 1.Research Centre Jülich, Institute for Neuroscience and Medicine (INM-1, INM-2), Jülich, Germany;2.Jülich-Aachen Research Alliance (JARA), RWTH Aachen University, Department of Psychiatry and Psychotherapy, Aachen, Germany;3.Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany;4.C. u. O. Vogt-Institute for Brain Research, University of Duesseldorf, Duesseldorf, Germany;New York University, United States of America |
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Abstract: | There is a considerable contrast between the various functions assigned to Broca''s region and its relatively simple subdivision into two cytoarchitectonic areas (44 and 45). Since the regional distribution of transmitter receptors in the cerebral cortex has been proven a powerful indicator of functional diversity, the subdivision of Broca''s region was analyzed here using a multireceptor approach. The distribution patterns of six receptor types using in vitro receptor autoradiography revealed previously unknown areas: a ventral precentral transitional cortex 6r1, dorsal and ventral areas 44d and 44v, anterior and posterior areas 45a and 45p, and areas op8 and op9 in the frontal operculum. A significant lateralization of receptors was demonstrated with respect to the cholinergic M2 receptor, particularly in area 44v+d. We propose a new concept of the anterior language region, which elucidates the relation between premotor cortex, prefrontal cortex, and Broca''s region. It offers human brain homologues to the recently described subdivision of area 45, and the segregation of the ventral premotor cortex in macaque brains. The results provide a novel structural basis of the organization of language regions in the brain. |
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