Optical mapping/imaging of neural activity in the spinal cord : investigation for possible mechanisms of dysesthesia

为了研究感觉障碍的可能机制，我们使用多位点光学记录/成像技术研究了胚胎和成人脊髓中神经元通路/网络活动的时空模式。在胚胎实验中，分别从鸡和大鼠胚胎中解剖脊髓，在完整的第13颈脊神经或第2、第5腰骶脊神经的基础上制备横切片。切片用电压敏感的merocyanine-rhodanine染料（NK2761）染色。采用128或1020元光电二极管阵列，同时记录了利用吸电极以正方电流脉冲刺激脊神经所引起的跨膜电压相关光学（染料吸收）变化。在对应于后（背）和前（腹）灰质的背侧和腹侧区域检测到光学反应。光信号由两部分组成，即快速峰状信号和慢速信号。在背侧区域，快速的尖峰样信号被识别为感觉神经的突触前动作电位，而缓慢的信号被识别为突触后电位。在腹侧区，快速的尖峰样信号反映了运动神经元的反向动作电位，而缓慢的信号则与运动神经元突触后电位的诱发有关。在成人脊髓实验中，我们探讨了脊髓神经刺激诱发大鼠脊髓内固有光学成像的可行性。用聚氨酯麻醉成年大鼠，d-管碱固定大鼠。在C5和Th1之间行椎板切除术以暴露颈脊髓。切除正中神经和尺神经，在前肢植入双极电极。使用差分视频采集系统记录脊髓对正中神经和尺神经刺激的光学反射变化。在颈脊髓背侧，C6和C8之间可见明显的本征光信号，且信号振幅随刺激强度成比例增大。外周神经刺激在颈脊髓背侧引起的反应可能是主要传入神经元和背角突触后神经元的神经活动。少

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 … More 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