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Findings suggest that the autism spectrum disorder (ASD) can be caused by disruptions occurring very early on, when the cerebral cortex is just beginning to construct itself. The cerebral cortex – which in humans is responsible for higher brain functioning including perception, speech, long-term memory, and consciousness – is relatively large and dominant compared to the other brain structures.
Studies have found that precursor cells called radial glial cells (RGCs) appear at the bottom of the developing cortex in a regularly spaced or tiled pattern. RGCs divide to form young cortical neurons, and these baby neurons climb the scaffold to find their proper places in the developing brain. The cortex develops a highly regular structure with six distinct layers of neurons required for the normal formation of functional neural cortical circuits.
Anton and colleagues discovered that a gene encoding for a protein called Memo1 is needed to organize the tiled radial glial cell scaffold. Mutations in the Memo1 gene also have been found in some people with autism and are suspected of causing the condition. Results have shown that the resulted RGC scaffold is disrupted – resulting in neuronal misplacement and disorganized layers.
Studies of brains of children with autism found patches of similar neuronal disorganisation. Scientists then analysed MEMO 1 gene mutations reported in individuals with autism behaviours and intellectual disabilities. They discovered that the human MEMO1 genetic mutation resulted in a shortened form of the Memo1 protein and this can disrupt RGC development.
These analyses further supported the autism connection, showing a lack of explorative activity like those seen in some people with autism. The findings overall suggest that Memo1-associated autism may be wired into the brain very early in development than are other forms of autism with origins in disrupted neuronal differentiation and connectivity.
Source material from Science Daily