A team of Japanese researchers has shed light on why the brain's left side is functionally different from its right side by finding structural differences of synapses, points where electrical signals move from one nerve cell to another.
While language understanding is a function performed by left hemisphere of the brain, the right hemisphere of the brain looks after spatial recognition.
Prof. Ryuichi Shigemoto in National Institute for Physiological Sciences and Dr. Yoshiaki Shinohara found that synaptic size and shape in the centre of the spatial memory (i.e. hippocampus) were asymmetrical between synapses receiving input from the left and right hemisphere.
Investigating the electron microscopic structure of synapses in left and right hippocampus, the team found that synapses made by terminals from the right hippocampus were large, complex in shape, and rich in the GluR1 subunit of AMPA-type glutamate receptors.
On the other hand, synapses receiving input from the left hippocampus were small and rich in the NR2B subunit of NMDA receptors.
The researchers said that such differences suggest that both synaptic structure and synaptic molecules differ between synapses with left and right inputs.
Long-term potentiaon (LTP), that is known as the cellular mechanism of learning and memory, depends on the allocation of glutamate receptors in hippocampus. According to our present finding, synapses receiving right input may be more suitable to initiate LTP. This finding may help understand how our left and right brains work differently, said Prof Shigemoto of the Japanese team.
An article describing the study has been published in the Proceedings of National Academy of Sciences.