On (ab)normality: Einstein's fusiform gyrus.

Recently, Hines (2014) wrote an evocative paper challenging findings from both histological and morphological studies of Einstein's brain. In this discussion paper, I extend Hines' theoretical point and further discuss how best to determine 'abnormal' morphology. To do so, I assess the sulcal patterning of Einstein's fusiform gyrus (FG) for the first time. The sulcal patterning of the FG was unconsidered in prior studies because the morphological features of the mid-fusiform sulcus have only been clarified recently. On the one hand, the sulcal patterning of Einstein's FG is abnormal relative to averages of 'normal' brains generated from two independent datasets (N = 39 and N = 15, respectively). On the other hand, within the 108 hemispheres used to make these average brains, it is not impossible to find FG sulcal patterns that resemble those of Einstein. Thus, concluding whether a morphological pattern is normal or abnormal heavily depends on the chosen analysis method (e.g. group average vs. individual). Such findings question the functional meaning of morphological 'abnormalities' when determined by comparing an individual to an average brain or average frequency characteristics. These observations are not only important for analyzing a rare brain such as that of Einstein, but also for comparing macroanatomical features between typical and atypical populations.