Asymmetry of Chimpanzee Planum Temporale: Humanlike Pattern of Wernicke's Brain Language Area Homolog

Ojemann G. A., Adv. Neurol. 63, 155 (1993);

; J. Neurosci. 11, 2281 (1991).

Geschwind N., Levitsky W., Science 161, 186 (1968).

Clavert G. A., et al., ibid. 276, 593 (1997);

Habib M., Robichon F., Levrier O., Khalil R., Salamon G., Brain Lang. 48, 238 (1995);

Just M. A., Carpenter P. A., Keller A., Eddy W. F., Thulborn K. R., Science 274, 114 (1997);

; G. Hickok, U. Bellugi, E. S.Klima, Nature381, 699 (1996); H. Poizner, E. S. Klima, U. Bellugi, What the Hands Reveal About the Brain (MIT Press, Cambridge, MA, 1987).

N. Geschwind and A. M. Galaburda, Arch. Neurol. 42, 428, 521, and 634 (1985).

Foundas A. L., Leonard C. M., Gilmore R., Fennell E., Heilman K. M., Neuropsychologia 32, 1225 (1994).

Lynch M. P., Behav. Brain Sci. 19, 788 (1996);

Schlaug G., Jancke L., Huang Y., Steinmetz H., Science 267, 699 (1995).

Witelson S. F., Pallie W., Brain 96, 641 (1973).

Annett M., Neuropsychologia 30, 951 (1992);

Steinmetz H., Volkmann J., Janke L., Freund H. J., Ann. Neurol. 29, 315 (1991) .

Harasty J., Double K. L., Halliday G. M., Kril J. J., Mc Ritchie D. A., Arch. Neurol. 54, 171 (1997);

Witelson S. F., Psychoneuroendocrinology 16, 131 (1991).

Crow T. J., Trends Neurosci. 20, 339 (1997);

Petty R. G., et al., Am. J. Psychiatry 152, 715 (1995).

R. A. Pfeifer, in Handbuch der Neurologie, O. Bumke and O. Foerster, Eds. (Springer, Berlin, 1936), vol. 6, p. 533.

C. von Economo and L. Horn, Z. Ges. Neurol. Psychiatr. 130, 678 (1930).

LeMay M., Geschwind N., Brain Behav. Evol. 11, 48 (1975).

Yeni-Komshian G. H., Benson D. A., Science 192, 387 (1976).

D. Falk, J. Cheverud, M. W. Vannier, G. C. Conroy, Folia Primatol. 46, 98 (1986); P. J. Gannon, thesis, City University of New York (1995);

Heilbroner P. L., Holloway R. L., Am. J. Phys. Anthropol. 76, 39 (1988).

Holloway R. L., Am. J. Phys. Anthropol. 53, 285 (1980);

LeMay M., Ann. N.Y. Acad. Sci. 280, 349 (1976);

Tobias P. V., J. Hum. Evol. 16, 741 (1987).

Eleven chimpanzee brains from the collection of Dr. Ralph Holloway and four from the Yerkes Primate Center (YN97-139, YN92-115, YN88-256, and YN77-117) were used (thanks to Daniel Anderson, Jeremy Dahl, and Harold McClure; and to James Rilling, Department of Anthropology, Emory University). The cortical surface area of the PT in these 15 brains was quantified as described below (21). Three brains from the Smithsonian Institution were also used (SI-292178, SI-225776, and SI-292176) (thanks to Dr. Richard W. Thorington Jr., Linda K. Gordon, and Jeremy Jacobs, Department of Vertebrate Zoology.) Two of us (P.J.G. and A.R.B.) first noted marked asymmetry of the PT and Heschl's gyrus in these three brains during a magnetic resonance imaging study. Because of the friable nature of these three brains, the SF could not be spread widely; thus, the lateral margin of the PT was quantified with calipers. Results showed that the PT was 51 ± 40% larger on the left than on the right (49, 12, and 91% greater on the left than on the right, respectively).

Foundas A. L, Leonard C. M., Heilman K. M., Arch. Neurol. 52, 501 (1995);

Galaburda A. M., ibid. 50, 457 (1993);

Rossi A., et al., Brain Lang. 47, 89 (1994);

; H. Steinmetz et al., J. Comput. Assisted Tomogr. 13, 996 (1989).

The quantitative method employed here, which accounted for the 3D complexity of the PT unlike methods used previously, involved the following. (i) After wide spreading of the SF to obtain an unobstructed view of the PT, and with the use of an operating microscope at magnification ×4 to ×10, three of us (P.J.G., R.L.H., and D.C.B.) identified the suite of defined structures that demarcate the borders of the PT (20). In brief, these are as follows. Anterior: Heschl's sulcus, which forms the posterior border of Heschl's gyrus. In the event of a secondary posterior portion of Heschl's gyrus, the criterion used to include this within the PT was if it comprised a distinct retroinsular pedicle of origin. Lateral: superolateral margin of the superior temporal convolutions. Posterior: the termination of the horizontal portion of the SF. A distinct ridge, formed at the point of diversion of the horizontal and descending limbs of the SF was apparent (arrows in Fig. 1). Medial: the retroinsular point forming the apex of the approximately triangular PT. (ii) A sheet of thin black plastic was formed to fit precisely within the defined margins of the PT. The thin flexible plastic conformed to the 3D complexity of the PT and was able to be inserted within Heschl's sulcus even in cases where this structure was deeply invaginated (asterisk in Fig. 1). (iii) The black plastic templates were attached to white cards and scanned at 150 dots per inch into TIFF files. Their area was then determined in millimeters with the use of SigmaScanPro. Statistical analysis (Statistical Package for the Social Sciences) included analysis of variance and paired t tests.

P. Bailey, G. von Bonin, W. S. McCulloch, The Isocortex of the Chimpanzee (University of Illinois, Urbana, 1950);

Galaburda A. M., Sanides F., J. Comp. Neurol. 190, 597 (1980);

Galaburda A. M., Sanides F., Geschwind N., Arch. Neurol. 35, 812 (1978).

H. D. Steklis, personal communication; J. Vauclair, Trends Cogn. Neurosci. 1, 35 (1997).

Kioyashi H., Koshima S., Nature 387, 767 (1997);

De Waal F., Discover 18, 50 (1997);

Greenfield P. M., Savage-Rumbaugh E. S., J. Child Lang. 20, 1 (1993);

Savage-Rumbaugh E. S., et al., Monogr. Soc. Res. Child Dev. 58, 1 (1993);

Gardner B. T., Gardner R. A., J. Hum. Evol. 4, 433 (1989);

; J. Goodall, The Chimpanzees of Gombe (Belknap, Cambridge, MA, 1986); H. D. Steklis and M. J. Raleigh, Neurobiology of Social Communication in Primates (Academic Press, New York, 1979);

Gallup G. G., Science 167, 86 (1970).

Binder J. R, Frost J. A., Hammeke T. A., Rao S. M., Cox R. W, Brain 119, 1239 (1996).

T. W. Deacon, in The Evolution of Human Languages, J. A. Hawkins and M. Gel-Man, Eds. (Addison-Wesley, Reading, MA, 1992), vol. XI, pp. 49–83.

This work was supported by a grant from NSF and from the Department of Otolaryngology and The Grabscheid Voice Center, Mount Sinai School of Medicine, New York. We thank E. C. Azmitia, K. J. Chandross, L. deCarava, N. M. Kheck, J. T. Laitman, S. Marquez, I. Sanders, S. Selbie, M. L. Urken, M. Yuan, and R. J. Zatorre for their help.