| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1999: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1998: ¥2,100,000 (Direct Cost: ¥2,100,000)
|
|---|
| Research Abstract |
The long descending reticulospinal and vestibulospinal pathways originate mainly from the medial pontomedullary reticular formation (PMRF) and the lateral vestibular nucleus (LVN), respectively. These pathways comprise the most primitive descending motor systems, projecting throughout the whole length of the spinal cord, and terminating mainly in the internuncial layers of the gray matter. As part of an attempt to understand the functional role played by these systems, we have performed a series of tracing studies in the cat, utilizing the anterograde neural tracer, Phaseolus vulgaris-leucoagglutinin (PHA-L), with the purpose of identifying the fine architecture of the reticulospinal and vestibulospinal pathways. Localized injections of PHA-L were made into the medial pontine reticular formation (PRF) and the LVN in cats. Following survival periods of 6 to 12 weeks, PHA-L-labeled axons from the PRF and LVN were found throughout the whole extent of the spinal neuraxis. From serial trans
… More
verse sections (50 μm), trajectories of 21 single pontine reticulospinal (RS) axons were traced in continuity over 3-6 segments in the lumbar enlargements at 14 to S2. All the identified axons gave off multiple axon collateral along their courses. The trajectories of 28 single lateral vestibulospinal tract (LVST) axons were also traced from serial transverse sections of the spinal cord from CI-8 (n=10), Tl-9 (11), and Tll-L7 (7). They also gave off multiple axon collateral along their descending courses. Collateral fibers from both RS and LVST axons commonly terminated mainly in laminae VIII and VII of the ventral horn. These findings indicate that single long descending RS and LVST axons innervate the spinal interneuronal nuclei at multiple segments with a high degree of collateralization along the full extent of the spinal neuraxis. Such arrangement of the reticulospinal and vestibulospinal pathways appears to be well suited for control of the activity of the large number of muscles, as is necessary for the execution of interlimb and/or limb-trunk coordinated movements. Less
|
