Geschwind–Galaburda hypothesis

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The Geschwind–Galaburda hypothesis was proposed by Norman Geschwind and Albert Galaburda to explain sex differences in cognitive abilities by relating them to lateralization of brain function. The basic idea is that differences in maturation rates between the cerebral hemispheres are mediated by circulating testosterone levels, and that sexual maturation acts to fix the hemispheres at different relative stages of development after puberty.


According to the theory, male brains mature later than females, and the left hemisphere matures later than the right.


Although the Geschwind-Galaburda hypothesis has been cited in mainstream media and publication resources as a cause for left-handedness, very little research evidence (if any) has been presented to substantiate the theory. In fact, evidence has emerged suggesting that high prenatal estrogen exposure is just as likely to enhance the gene expression for left-handedness. In a study endorsed by the Centers for Disease Control (CDC), it is suggested that men who were prenatally exposed to diethylstilbestrol (a synthetic estrogen based fertility drug), are more likely to be left-handed than unexposed men. [1]

See also

References and further reading

  1. Titus-Ernstoff L, et al. (2003). "Psychosexual Characteristics of Men and Women Exposed Prenatally to Diethylstilbestrol". Centers for Disease Control.

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Daniel H. Geschwind is the Gordon and Virginia MacDonald Distinguished Professor of Human Genetics, Neurology and Psychiatry at the David Geffen School of Medicine at the University of California, Los Angeles (UCLA). He also directs the UCLA Neurogenetics Program and the UCLA Center for Autism Research and Treatment (CART), and holds the Gordon and Virginia MacDonald Distinguished Chair of Human Genetics there. Since March 1, 2016, he has served as the Senior Associate Dean and Associate Vice Chancellor for Precision Medicine at UCLA. His brother, Michael Geschwind, is also a professor of neurology, and behavioral neurology pioneer Norman Geschwind is his father's first cousin.

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Albert Galaburda

Albert Mark Galaburda is a cognitive and behavioral neurologist with a special focus on the biologic bases of developmental cognitive disorders. He is the Emily Fisher Landau Professor of Neurology and Neuroscience at Harvard Medical School, the Director of the Office for Diversity, Inclusion, and Career Advancement at Beth Israel Deaconess Medical Center, Boston, and Co-director of the Harvard University Interfaculty Initiative on Mind Brain and Behavior, together with psychologist Alfonso Caramazza. He is best known for his development of the Geschwind-Galaburda hypothesis, which helps explain differences in cognitive abilities on the basis of sex hormones and immunological characteristics and their relationship to lateralization of brain function, as well as for his pioneering studies on the biological foundations of developmental dyslexia. Other work includes the anatomical organization of the auditory cortex in the brains of monkeys and humans and the neuroanatomical and neurodevelopmental bases of brain laterality and asymmetry. He attended the Six-Year Liberal Arts-Medicine Program at Boston University School of Medicine, graduating with an AB-MD degree in 1971, and completed a residency in Internal Medicine and a residency in Neurology at Boston City Hospital, now Boston Medical Center. He was trained in Medicine under Norman Levinsky and in Neurology under Norman Geschwind. He has published numerous scientific articles and books in the field of cognitive neurology, with a focus on learning disabilities and attention disorders, especially in adults.