I speak with autistic adults everyday and almost all of them tell me about the flooding, the sensory overload, the feelings of overwhelm that lead to shut down and/or hyper-focus.
We may finally have a neurobiological reason for that overload and that reason lies in what are called Astrocytes. Apparently, astrocytes help dictate the inhibition or excitation in the brain. While many scientists have focused their research solely on the neurons due to their being easier to study - they are the ones that conduct electricity so we can see and study them more easily - but the astrocytes may actually be center stage in autism. Interestingly, astrocytes were actually discovered in 1895 but only recently (the last 15 years) been the center of studies.
For an excellent summary article, please go to the Spectrum News article by clicking below.