Bangalore scientists crack brain cell codes that trigger autism

Indian neuroscientists have discovered details of defects in brain cell junctions that cause the debilitating emotional symptoms of Fragile X Syndrome (FXS).
FXS is the most common inherited cause of autism and mental retardation.
A National Centre for Biological Sciences (NCBS) team, led by Professor Sumantra Chattarji, and their collaborators at the New York University (NYU) studied how cells and synapses in the amygdala, the tiny emotional hub of the brain, are affected in mice with FXS.
Their paper was published on Monday in the journal, Proceedings of the National Academy of Sciences. A synapse is a junction of two neurons (nerve cells) through which impulses pass by diffusion of a set of brain chemicals called neurotransmitters.
Such signal transmission is what makes the brain work. Many of the emotional and cognitive symptoms of FXS are caused by defects in such signalling.
When the neurons fire impulses through the synapses, a neurotransmitter called glutamate is released in one neuron and it activates special receptor molecules in the next neuron.
Thus signals get relayed.
While there are different types of receptors at the synapse, abnormally high signalling through one particular class - the group 1 metabotropic glutamate receptor - is implicated in many of the symptoms seen in FXS. Recording the electric activity involved in the signalling, Aparna Suvrathan, a graduate student in Chattarji's lab, identified defects at the sending and receiving ends of the synapses.
The molecular nature of these defects were analysed by Professor Eric Klann and his colleagues at NYU. They noted that these deficits severely impaired the ability of neurons to communicate and encode information.