Science Topics – 106

The mechanism in the brain for motor learning.
Hiroyuki Kida (Dai Mitsushima)

We keep on practicing, because we want to get better, and as we practice hard, we gradually have the feeling to do better than previously. A group including Assistant Professor Hiroyuki Kida and Professor Dai Mitsushima from Yamaguchi University Graduate School of Medicine's Department of Physiology has focused on synaptic plasticity in layers II/III of the primary motor cortex (M1), and has observed how they change after training. In the experiment, we subjected rats to a rotor rod test and then prepared acute brain slices. Our present results indicate dynamic changes in glutamatergic, GABAergic in M1 layer II/III neurons after the motor training.

On the first day of the training, GABA release temporarily decreased at the inhibitory synapses, and the number of AMPA-type glutamic acid receptors increased at the excitatory synapses. On the second day of the training, the GABA release at the inhibitory synapses recovered, but the number of AMPA receptors at the excitatory synapses continued to increase, and the glutamate release also increased compared with what it had been before the training.

The research showed that the balance between excitatory and inhibitory synapses changes dynamically, and that individual synapses diversify and undergo developmental changes in response to the stage of motor learning. It is anticipated that the clarification of the synaptic / molecular mechanism for motor proficiency will find applications in the treatment of motor function disabilities and rehabilitation medicine.

Kida H, Tsuda Y, Ito N, Yamamoto Y, Owada Y, Kamiya Y, Mitsushima D.
Motor training promotes both synaptic and intrinsic plasticity of layer II/III pyramidal neurons in the primary motor cortex. Cerebral Cortex, in press, 2016.

Department of Physiology, Yamaguchi University Graduate School of Medicine's Department of Physiology