| Budget Amount *help |
¥4,020,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2006: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Neostriatal projection neurons are divided into two groups ; neurons projecting to the substantia nigra (SN) and internal segment of the globus pallidus (GPi) and those projecting to the external segment of the globus pallidus (GPe). The former is called 'direct pathway' neurons in the basal ganglia circuit, since those neurons directly send axons to the output nuclei of the basal ganglia, i.e. pars reticulata of the SN (SNr) and GPi. On the other hand, the latter striato-GPe neurons participate in the 'indirect pathway' which is composed of striato-GPe, GPe-subthalamic and subthalamo-GPi/SNr projections. In addition to the two segregated striatofugal groups, the neostriatum possesses a mosaic organization composed of patch and matrix compartments. The patch compartment occupys 10-15% of the neostriatal volume and characterized by projection to the pars compacta of the SN (SNc). Furthermore, patch regions are visualized with intense immunoreactivity for mu-opioid receptor. In the reinforcement learning, neostriatal neurons in the patch/striosome and matrix compartments are presumed to serve as state-value and action-value functions. However, the way of mutual coexistence of the "direct and indirect pathways" and the " patch and matrix compartments" has not been clarified. To address this question, we examined the striatopetal and striatofugal pathways related with patch and matrix compartments using the recombinant Sindbis virus vector, preproenkephalin/GFP BAC transgenic mouse and vesicular glutamate transporters. With these experiments, we are beginning to clarify the relationship between dual striatofugal system and anatomical compartments, and they will enable us to obtain new scheme of the basal ganglia network.
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