“Structural foundation of neural circuits that are involved during the acquisition and consolidation of a skill”

In motor learning, there exist two phases: a phase for acquiring skills through trial and error (early phase) and a phase for further improving the skill after proficiency (late phase). Recent studies have reported that for the process of this motor learning, the functional shift between different regions of the striatum is involved (Yin et al., 2009).

The region of the striatum is connected with the different cerebral cortical areas. The factors that define the cerebral cortico-basal ganglia-thalamic loop have also been reported to include the layer structure of the cerebral cortex, striosome/matrix structure of the striatum, thalamic subnuclei, and the mutual relationship of these elements. It is important to identify the “true functional area” within this complex network. We have reported that the cortico-basal ganglia-thalamic loop is not by the orderly relay between point-to-point or each site, and is inconsistent with the conventional direct and indirect pathway scheme, by using morphological techniques incorporating molecular biological techniques, such as labeling single neurons.

Our collaborator (Dr. Karube) elucidate a new cortico-basal ganglia-thalamic loop, and verify its functionality through the combination of morphological and electrophysiological techniques. In addition, another collaborator (Dr. Takahashi) has conducted a study of the plasticity of cell assembly in the brain of freely moving rodents. It enables us to analyze the multi-neuron recording of rats at each stage during motor learning, and the impact on the neural circuitry by Deep Brain Stimulation (DBS) and optogenetic techniques.

Further, in order to perform cell-type specific manipulation of the circuit, it is necessary to examine the biochemical characteristics of each neuron and the relationship at the synaptic level of the receptors and neurotransmitters released from the projection target axon terminals. Our collaborator (Dr. Kubota) has been establishing an analysis method of three-dimensional electron microscopy (Kubota, 2014; DeFelipe et al, 2013).

Our new knowledge will provide a basis for understanding how the basal ganglia influence cognitive as well as motor functions and how the network or synaptic organization are changed during the acquisition and consolidation of a skill.

 
Recent Publications
1. Unzai T , Kuramoto E, Kaneko T, Fujiyama F. Quantitative Analyses of the Projection of individual Neurons from the Midline Thalamic Nuclei to the Striosome and Matrix Compartments of the Rat Striatum. Cerebral Cortex, 2016
2. Fujiyama F, Nakano T, Matsuda W, Furuta T, Udagawa J, Kaneko T. A Single-Neuron Tracing Study of Arkypallidal and Prototypic Neurons in Healthy Rats. Brain Structure and Function, 2016
3. Fujiyama F, Karube F, Takahashi S. Morphological elucidation of basal ganglia circuits contributing reward prediction. Frontiers in Neuroscience, 2015.

Posted:2016/02/23