EFFECTS OF ECMA (ETHYLCHOLINE MUSTARD AZIRIDINIUM ION)ON THE RESPONSE PROPERTIES OF THE RETINAL GANGLION UNITS IN PIGEON
神经毒素ECMA对家鸽视网膜神经节单元反应特性的影响

A total of 101 retinal ganglion units were recorded from axons and terminal arbours in the superficial layer of the optic tectum of pigeon (Columba livia) and quantitatively analyzed to study the effects of ECMA-lesion on the response properties of retinal ganglion units.In control group, units could be classified into the ON, OFF and ON-OFF transient responses to flashing spots. In response to the moving bars, 14 out of 42 unitS (29%) were directionally selective and the others were only motion-sensitive. The null directions of the directionally selective units were not evenly distributed. 8 out of them had their null directions from anterior in the receptive field to the back, while none was its null direction from posterior in the field to the front.After ECMA-lesion of the retina, only ON-OFF and ON responses were recorded and they almost showed a sustained ON-response component which was not detected in the control group. The directionally selective units did not be found in response to moving bar and all units were non -directional motion -sensitive.It was discussed that the mechanism underlying the disappearance of the transient responses and of the directional selectivity of ganglion units might be due to elimination of the cholinergic amacrine cells with ECMA.