Fig. 1
From: The ASD Living Biology: from cell proliferation to clinical phenotype
Illustration of early brain overgrowth in ASD. Brain overgrowth in the first years of life occurs in many ASD toddlers and is due to prenatal cell cycle dysregulation that causes an overabundance of cortical neurons. This is theorized to lead to disrupted neural network development and function, and ASD symptoms [5,6,7, 24, 31,32,33,34]. Unbiased, blinded stereological analyses find that young ASD male children have an average 67% more prefrontal neurons than controls [24]. Since cortical neuron generation occurs only in prenatal life in humans, this is direct evidence that ASD begins in the womb. As discussed in this review and previously [56], abnormal early brain undergrowth in toddlers with ASD may also be due to cell cycle dysregulation. Adapted from Courchesne et al. [7]
