Variability of Broca's area homologue in African great apes: Implications for language evolution

Chet C. Sherwood, Douglas C Broadfield, Ralph L. Holloway, Patrick J. Gannon, Patrick R. Hof

Research output: Contribution to journalArticle

103 Citations (Scopus)

Abstract

The cortical circuits subserving neural processing of human language are localized to the inferior frontal operculum and the posterior perisylvian region. Functional language dominance has been related to anatomical asymmetry of Broca's area and the planum temporale. The evolutionary history of these asymmetric patterns, however, remains obscure. Although testing of hypotheses about the evolution of language areas requires comparison to homologous regions in the brains of our closest living relatives, the great apes, to date little is known about normal interindividual variation of these regions in this group. Here we focus on Brodmann's area 44 in African great apes (Pan troglodytes and Gorilla gorilla). This area corresponds to the pars opercularis of the inferior frontal gyrus (IFG), and has been shown to exhibit both gross and cytoarchitectural asymmetries in humans. We calculated frequencies of sulcal variations and mapped the distribution of cytoarchitectural area 44 to determine whether its boundaries occurred at consistent macrostructural landmarks. A considerable amount of variation was found in the distribution of the inferior frontal sulci among great ape brains. The inferior precentral sulcus in particular was often bifurcated, which made it impossible to determine the posterior boundary of the pars opercularis. In addition, the distribution of Brodmann's area 44 showed very little correspondence to surface anatomy. We conclude that gross morphologic patterns do not offer substantive landmarks for the measurement of Brodmann's area 44 in great apes. Whether or not Broca's area homologue of great apes exhibits humanlike asymmetry can only be resolved through further analyses of microstructural components.

Original languageEnglish (US)
Pages (from-to)276-285
Number of pages10
JournalAnatomical Record - Part A Discoveries in Molecular, Cellular, and Evolutionary Biology
Volume271
Issue number2
StatePublished - Apr 1 2003
Externally publishedYes

Fingerprint

Hominidae
Pongidae
Language
Prefrontal Cortex
Gorilla gorilla
brain
Temazepam
Pan troglodytes
Brain
Anatomy
History
Broca Area
history
testing

Keywords

  • Brain evolution
  • Broca's area
  • Chimpanzee
  • Gorilla
  • Great apes
  • Language

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Anatomy

Cite this

Variability of Broca's area homologue in African great apes : Implications for language evolution. / Sherwood, Chet C.; Broadfield, Douglas C; Holloway, Ralph L.; Gannon, Patrick J.; Hof, Patrick R.

In: Anatomical Record - Part A Discoveries in Molecular, Cellular, and Evolutionary Biology, Vol. 271, No. 2, 01.04.2003, p. 276-285.

Research output: Contribution to journalArticle

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