Brain cells
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New Delhi: A faster-than-normal development of brain could be a possible reason for humans to develop intellectual disabilities or autism, according to a study.
Brain cells or neurons, especially those in the cognition region -- the cerebral cortex -- take years to fully mature, a process called 'neoteny' and known to be critical for developing advanced cognitive (thinking) processes distinct to humans.
The gene SYNGAP1, according to researchers, encourages a prolonged development of these neurons.
However, the researchers at the Flemish Institute for Biotechnology, Belgium, found that changes or mutations to the gene disrupted the prolonged development, which they said could underlie some forms of intellectual disability and autism.
Intellectual disabilities refer to a set of neurodevelopmental conditions that affect one's functioning in two aspects - cognitive (thinking) processes, including learning and problem solving, and adaptive processes involving daily activities such as communication and being social. Autism is a neurodevelopmental disorder in which one displays repetitive behaviour along with affected social skills.
For the study, published in the journal Neuron, the researchers transplanted human neurons having mutated SYNGAP1 genes into brains of mice and then followed their development and function.
Studying the connections between neurons in the mice, the mutated neurons were found to "display a strong acceleration of their development" even as they "looked normal in most aspects", according to first author Ben Vermaercke.
"Most strikingly, they connected much faster with other neurons," Vermaercke said.
The mutated neurons merged faster into those in the cortical region and responded to visual information months ahead of their normal development schedule, indicating that maturing quickly led to early functionality of the neurons, the authors said.
While the previous studies have found that changes to the SYNGAP1 gene are a major cause of intellectual disabilities, the specific effects of the resulting disruption to the brain cells remained largely unknown, according to the researchers.
The findings have implications for understanding and developing treatment for intellectual disabilities and autism, they said.