Op-brai130254 1..8

Sir, Albert Einstein was arguably the greatest physicist in the 20th century and his extraordinary intelligence has long intrigued both scientists and the general public. Despite several studies that focused mainly on the histological and morphological features of Einstein’s brain after his death, the substrates of Einstein’s genius are still a mystery (Diamond et al., 1985; Anderson and Harvey, 1996; Kigar et al., 1997; Hines, 1998; Witelson et al., 1999a, b; Colombo et al., 2006; Falk, 2009). Recently, Falk et al. (2013) analysed 14 newly discovered photographs and found that Einstein’s brain had an extraordinary prefrontal cortex, and that inferior portions of the primary somatosensory and motor cortices were greatly expanded in the left hemisphere. Among these 14 images were photographs of the left and right medial surface of Einstein’s brain, on which the corpus callosum was shown with great resolution and accuracy. The corpus callosum is the largest nerve fibre bundle that connects the cortical regions of the cerebral hemispheres in human brains and it plays an essential role in the integration of information transferred between the hemispheres over thousands of axons (Aboitiz et al., 1992). The two photographs of the medial surfaces of Einstein’s cerebral hemispheres provide the basis for the present study. To examine whether there are regional callosal differences between the brain of Einstein and those of ordinary people, and to minimize potential differences in corpus callosum morphology due to cause of death, brain atrophy, age, and sex, in vivo MRI data sets from two different age groups were used. The highresolution photographs of Einstein’s left and right hemispheres were supplied by Dean Falk with permission from the National Museum of Health and Medicine (Fig. 1). Because Einstein was right-handed and died at the age of 76, our first control group consisted of 15 elderly, healthy right-handed males, aged 70 to 80 years (mean: 74.20 2.60 years). All participants were college graduates or beyond college, and non-demented (Clinical Dementia Rating = 0, Mini-Mental State Examination was from 28 to 30, mean SD: 29.53 0.64) (Marcus et al., 2007, 2010). The information regarding the subjects’ racial/ethnic backgrounds is unavailable. The T1-weighted MRI data of these 15 older males were obtained from the Open Access Series of Imaging Studies (OASIS, http://www.oasis-brains.org/). All images were acquired on a 1.5 T Vision scanner (Siemens) and a T1-weighted MPRAGE sequence, with the following parameters: repetition time/echo time/inversion time = 18 ms/10 ms/20ms, 128 contiguous 1.25 mm sagittal slices, and voxel size = 1 1 1.25 mm. Our second control group consisted of 52 younger, healthy right-handed Caucasian males, aged 24 to 30 years (mean: 26.60 2.19 years). The reasons for selection are described in the Supplementary material. The high resolution T1weighted MRI data of these 52 Caucasian males were obtained from the International Consortium for Brain Mapping (ICBM) database (www.loni.ucla.edu/ICBM). Thirty-five of the MRI data sets were acquired on a Philips 1.5 T ACSIII scanner (Philips Intera, Philips Medical System) and a 3D T1-weighted sequence (T1-FFE) with the following parameters: repetition time/echo time = 18 ms/ 10 ms, 160–190 contiguous 1 mm sagittal slices, and voxel size = 1 1 1 mm. The remaining 17 MRI data sets were doi:10.1093/brain/awt252 Brain 2014: 137; 1–8 | e268