| Budget Amount *help |
¥14,500,000 (Direct Cost: ¥14,500,000)
Fiscal Year 2005: ¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 2004: ¥7,500,000 (Direct Cost: ¥7,500,000)
|
|---|
| Research Abstract |
To elucidate the anatomical basis underlying the role of the associative regions of the insect brain such as the mushroom body (MB), we studied how the MB of Drosophila is organized by its intrinsic and extrinsic neurons. We screened for the GAL4 enhancer-trap strains that label specific subsets of these neurons, and identified seven subtypes of the Kenyon cells and three other putative intrinsic neurons. We found a small subregion of the calyx, into which only a specific subtype of the Kenyon cells arborize. Kenyon cells divide the pedunculus into at least five concentric strata. The α', β', α and β lobes are each divided into three strata, whereas the γlobe appears more homogeneous. As for the MB extrinsic neurons (MBENs), we found three types of antennal lobe projection neurons among which two types are novel, and 13 other types of MBENs that arborize in the calyx, lobes, and pedunculus. The lobe-associated MBENs arborize in only specific areas of the lobes along their longitudinal axes, forming two to five segmented zones in each lobe. The laminar arrangement of the Kenyon cell axons and transverse arborization of the MBENs together divide the lobes into smaller synaptic units. Arborization patterns of each type of identified neurons within and outside of the MB were analyzed in detail. Our study suggests that, although Kenyon cells form rectilinear structure throughout the longitudinal axis of the lobes, the segmented organization of the MBENs may facilitate different ways of interaction between intrinsic and extrinsic neurons and might therefore result in different functional activity along the longitudinal lobe axes and between lobes.
|
