Narrow neural columns have been suggested to be a neuroanatomical abnormality in autism. A previous hypothetical explanation, an unbalance between excitatory and inhibitory lateral feedback in the neocortex, has been found to be difficult to reconcile with the relatively high comorbidity of autism with epilepsy. Two alternative explanations are discussed, an early low capacity for producing serotonin, documented in autism, and insufficient production of nitric oxide. An early low level of serotonin has in animal experiments caused narrow neural columns. Insufficient nitric oxide is known from neural network theory to cause narrow neural columns.
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