A micro-stimulation study on the supraspinal descending neurons underlying fish swimming.

1.对大鼠脑立体定位仪进行了改进，使之能用于小型鱼类的脑立体定位。2.用100 μ A、8毫秒、100 Hz或更低的负矩形电流微刺激鲤鱼的整个中脑区。用近阈电流刺激延髓内侧束核（Nfl）、延髓内侧束（flm）和结膜臂，可引起正常的游泳运动。3.在Nfl附近微量注射兴奋性氨基酸L-谷氨酸溶液。在大多数情况下，尾巴的运动引起同侧跳动。通过向两个Nfls的中间位置注射诱导对称的尾拍。5. HRP标记同侧Nfl内的flm，证实Nfl神经元通过同侧flm发出激活脊髓中枢模式发生器的信号。6.当电损伤一侧Nfl或flm时，不能使用同侧的轴肌。破坏红核或交叉鳃结膜造成的异常运动的对鳍。7.作为调查的下一步，我必须检查每个Nfl神经元和节段模式发生器之间的关系，网络的结构和更高的大脑区域的中脑运动区域的控制。

1.A stereotaxic apparatus for the rat was reconstructed to be usable for small fish by some modifications such as an addition of a gill-irrigating tube.2.The whole mid-brain region of the carp was micro-stimulated with negative rectangular current of 100muA,8msec, 100Hz, or lower. Swimming movement appeared normal was elicited by a stimulation with near threshold currents to the nucleus fasciculus longitudinalis medialis (Nfl), the fasciculus longitudinalis medialis (flm), and the brachium conjunctivum.3.Solution of an excitatory aminoacid, L-glutamate was micro-injected into the vicinity of Nfl. Tail movements beating toward the ipsilateral side were elicited in the most case. Symmetrical tail beats were induced by injections to the middle place of the both Nfls. No swimming occurred by injection to the nucleus ruber.4.HRP injections to flm of the one side labeled neurons in ipsilateral Nfl.5.These results confirm that it is Nfl neurons that send an signal activating the central pattern generators in the spinal cord through flm of the ipsilateral side.6.When Nfl or flm of the one side was destroved by an electric lesion, the fish could not use the axial muscles of the same side. Destruction of the nucleus ruber or the decussatio branchium conjunctivum caused abnormal movements in paired fins.7.As the next step of the investigation, I must examine relationships between each Nfl neuron and segmental pattern generators in the cord, architecture of the network and the control of the midbrain locomotor region by higher brain regions.