| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1999: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Research Abstract |
To examine the possible mechanisms for dysesthesia, we investigated spatiotemporal patterns of neuronal pathway/network activity in embryonic and adult spinal cords, using multiple-site optical recording/imaging techniques.
In experiments using embryos, spinal cords were dissected from chick and rat embryos, and transverse slice preparations were prepared with the 13th cervical spinal nerve or with the 2nd or 5th lumbosacral spinal nerve intact. The slice preparations were stained with a voltage-sensitive merocyanine-rhodanine dye (NK2761). Transmembrane voltage-related optical (dye-absorbance) changes evoked by spinal nerve stimulation with positive square current pulses using a suction electrode were recorded simultaneously from many loci in the preparation, using a 128- or 1020-element photodiode array. Optical responses were detected from dorsal and ventral regions corresponding to the posterior (dorsal) and anterior (ventral) gray matters. The optical signals were composed of two c
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omponents, fast spike-like and slow signals. In the dorsal region, the fast spike-like signal was identified as the presynaptic action potential in the sensory nerve, and the slow signal as the postsynaptic potential. In the ventral region, the fast spike-like signal reflected the antidromic action potential in motoneurons, and the slow signal was related to the postsynaptic potential evoked in the motoneuron.
In experiments using adult spinal cords, we made an examination of the feasibility of an intrinsic optical imaging evoked by spinal nerve stimulation in the in vivo rat spinal cord. Adult rats were anesthetized by Urethane and immobilized by d-tubocurarine. Laminectomy was performed between C5 and Th1 to expose the cervical spinal cord. Median and ulnar nerves were dissected and bipolar electrodes were implanted in the forelimb. Changes in optical reflectance were recorded from spinal cord in response to median and ulnar nerve stimulation using a differential video acquisition system. In the dorsal region of the cervical spinal cord, the intrinsic optical signals were detected clearly between C6 and C8, and the amplitude of the signals increased in proportion to the intensity of stimulation. The response evoked by peripheral nerve stimulation in the dorsal cervical spinal cord is suggested to be neural activities of the primary afferent and the postsynaptic neurons in the dorsal horn. Less
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