STUDIES ON THE NEURAL BASIS OF FISH SWIMMING

1.用Biocytin逆行标记鲤鱼脊髓，在两侧延髓内侧束核（Nflm）内共标记出近120个向脊髓投射的神经元，在两侧Nflm内共观察到近400个多巴胺能神经元。谷氨酰胺能神经元的大小分布包括标记的网状脊髓神经元的大小分布，这表明参与鱼类游泳启动的神经元必须是谷氨酰胺能神经元。2.在箭毒麻痹的鲤鱼中，同时记录了Nflm神经元和脊髓运动神经元的神经活动。在虚拟游泳过程中，观察到几种Nflm神经元表现出不同的神经元活动。1)在游泳过程中紧张性放电的神经元。2)与运动神经元爆发同相或异相放电的相位放电神经元。3)在游泳过程中停止放电的神经元。4)与游泳无关的神经元.在每个实验结束时，用从填充有示踪剂的记录电极释放的神经生物素标记记录的Nflm神经元。结果显示，Nflm内分布着不同活动模式的神经元.这些神经元活动中的一些也观察到在自由移动的鱼，在Nflm和OP放大器中装有电极。在头上。我猜想，紧张性神经元可能启动和维持具有身体波动的普通游泳，而不同类型的相性神经元可能调节游泳以减慢、加速、转向或停止。

1. By the retrograde neuronal labeling with Biocytin applied to the spinal cord of the carp , nearly 120 neurons projecting to the spinal cord were labeled in the nucleus fasciculus longitudinalis medialis (Nflm) of the both sides, while nearly 400 neurons with glutaminergic -immunoreaclivity were observed in Nflm of the both sides. Size distribution of glutaminergic neurons included that of the labeled reticurospinal neurons, suggesting that neurons that participate in initiation of fish swimming must be glutaminergic.2. Neural activities of Nflm neurons and the spinal motor neurons were recorded simultaneously in the carp paralyzed with curare. During fictive swimming, several kinds of Nflm neurons exhibiting different neuronal activities were observed. 1) tonically firing neurons during an episode of swimming. 2) phaslcally fired neurons firing on the phase or out of phase with motor neuron bursts. 3) neurons which cease firing during an episode of swimming. 4) neurons apparently irrelevant to the swimming.3. Recorded Nflm neurons were labeled with Neurobiotin released electrophoretically from recording electrodes filled with the tracer at the end of each experiment. This procedure revealed that the Nflm neurons with different activity patterns were distributed uniformly in Nflm.4. Some of these neuronal activities were also observed in free moving fish that were fitted with electrodes in Nflm and an OP amp. on the head.5. I guess that the tonic neurons may initiate and maintain ordinary swimming with body undulation, while the phasic neurons of different types may modulate swimming to slow down, speed up, turn or stop.