Correction: In the article “A Comparative Magnetic Resonance Imaging Study of the Anatomy, Variability, and Asymmetry of Broca's Area in the Human and Chimpanzee Brain” by Simon S. Keller, Neil Roberts, and William Hopkins, which appeared on pages 14607–14616 of the November 18, 2009 issue, there was an error. The authors reported that a diagonal sulcus was not identified in 30 chimpanzee subjects using magnetic resonance imaging (MRI). Since the publication of this article, the first author has completed an assessment of the frequency of the diagonal sulcus in an independent sample of 83 postmortem chimpanzee cerebral hemispheres at the Central Africa Museum in Tervuren, Belgium, with Dr. Emmanuel Gilissen. A clear sulcus was identified lying between the inferior precentral sulcus and fronto-orbital sulcus—suggestive of a diagonal sulcus—in at least 15 of these hemispheres. These more direct observations are likely to be more reliable than those that led to the claim in this article that the diagonal sulcus might not exist in the chimpanzee brain. The detailed results of this postmortem analysis will be published in the near future.
