The 16 brain regions examined represent a broad spectrum of brain structure– and neuron type specific differences in neuronal soma size.
In the past three decades, numerous studies have been conducted on the trajectory of brain overgrowth, differences between the sizes of individual brain structures and regions, and the abnormal number and size of neurons in the brain in autism spectrum disorder (ASD).
Although many chemicals induce neurotoxicity in utero or early infancy while basic brain structures are forming and neurons are proliferating and migrating, arsenic interrupts the development of synaptic connections, receptors, and transmitter systems, which continues for years after birth.
Within the hippocampus, and neighbouring brain structures, neurons exist that allow us to map space and find our way through it.
The pattern of developmental alterations of the brain structures' volume and number of neurons limited to these few brain regions is consistent with several morphometric and MRI studies, but is in striking contrast to the abnormal trajectories of neuronal soma volume growth detected in 14 of 16 examined brain structures of 4- to 8-year-old children with autism.
Leptin changes brain structure, neuron excitability and synaptic plasticity.
In the smallest examined brain structures, the number of neurons ranged from 0.7 million in the substantia nigra to 1.4 million in the lateral geniculate body.
Comparison of neurons in these brain structures in teenagers and adults does not reveal smaller neurons in the idiopathic autism than in the control group.
Experts found that the chemicals "may adversely affect the development of neurons and brain structures associated with functions such as learning and memory," an EFSA statement said.
Neuropathological commonalities range from developmental defects of neuronal proliferation and migration and dysplastic changes [ 43– 47] to reduced size of neurons in cortical minicolumns [ 48– 50] and neurons in brain structures related to autism diagnostic behavioral domains [ 51– 56], as well as abnormalities both related and not related directly to ASD [ 57– 61].
