Sunday, March 2, 2008

Broca's area in chimps?

Taglialatela JP, Russell JL, Schaeffer JA, Hopkins WD. 2008. Communicative signaling activates 'Broca's' homolog in chimpanzees. Curr Biol 18:1-6. doi:10.1016/j.cub.2008.01.049

Broca’s area, a cerebral cortical area located in the inferior frontal gyrus (IFG) of the human brain, has been identified as one of several critical regions associated with the motor planning and execution of language. Anatomically, Broca’s area is most often larger in the left hemisphere, and functional imaging studies in humans indicate significant left-lateralized patterns of activation during language-related tasks [1–3]. If, and to what extent, nonhuman primates, particularly chimpanzees, possess a homologous region that is involved in the production of their own communicative signals remains unknown. Here, we show that portions of the IFG as well as other cortical and subcortical regions in chimpanzees are active during the production of communicative signals. These findings are the first to provide direct evidence of the neuroanatomical structures associated with the production of communicative behaviors in chimpanzees. Significant activation in the left IFG in conjunction with other cortical and subcortical brain areas during the production of communicative signals in chimpanzees suggests that the neurological substrates underlying language production in the human brain may have been present in the common ancestor of humans and chimpanzees.
but in the conclusion:
Although these data indicate that the left IFG is involved in the production of communicative signals in chimpanzees, cytoarchitectonically, it is not clear what cell types fully comprise this region [36]. Therefore, it is not possible to determine whether or not the neuronal metabolic activity reported in this study corresponds to an area within the chimpanzee IFG that contains Brodmann’s area 44/45 cells—those cells that comprise Broca’s area in humans.

Too bad. I guess one has to manage to convince a chimp to get inside an MRI scanner and do a communicative task. Let's not forget that a chimp has the strength of six athletes.

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