Price Nicholas S C, Ibbotson Michael R
Visual Sciences, Research School of Biological Sciences, Australian National University, Canberra, ACT 2601, Australia.
J Neurophysiol. 2002 Nov;88(5):2224-31. doi: 10.1152/jn.00739.2001.
We describe the responses during and after motion of slow cells, which are a class of direction-selective neurons in the pretectal nucleus of the optic tract (NOT) of the wallaby. Neurons in the NOT respond to optic flow generated by head movements and drive compensatory optokinetic eye movements. Motion in the preferred direction produces increased firing rates in the cells, whereas motion in the opposite direction inhibits their high spontaneous activities. Neurons were stimulated with moving spatial sinusoidal gratings through a range of temporal and spatial frequencies. The slow cells were maximally stimulated at temporal frequencies <1 Hz and spatial frequencies of 0.13-1 cpd. During motion, the responses oscillate at the fundamental temporal frequency of the grating but not at higher-order harmonics. There is prolonged excitation after preferred direction motion and prolonged inhibition after anti-preferred direction motion, which are referred to as same-sign after-responses (SSARs). This is the first time that the response properties of neurons with SSARs have been reported and modeled in detail for neurons in the NOT. Slow cell responses during and after motion are modeled using an array of Reichardt-type motion detectors that include band-pass temporal prefilters. The oscillatory behavior during motion and the SSARs can be simulated accurately with the model by manipulating time constants associated with temporal filtering in the prefilters and motion detectors. The SSARs of slow cells are compared with those of previously described direction-selective neurons, which usually show transient inhibition or excitation after preferred or anti-preferred direction motion, respectively. Possible functional roles for slow cells are discussed in the context of eye movement control.
我们描述了慢速细胞在运动期间及之后的反应，慢速细胞是沙袋鼠视束前顶盖核（NOT）中的一类方向选择性神经元。NOT中的神经元对头部运动产生的视觉流作出反应，并驱动补偿性视动眼运动。在偏好方向上的运动会使细胞的放电频率增加，而在相反方向上的运动则会抑制其较高的自发活动。通过一系列时间和空间频率的移动空间正弦光栅对神经元进行刺激。慢速细胞在时间频率<1Hz和空间频率为0.13 - 1周/度时受到最大刺激。在运动期间，反应以光栅的基本时间频率振荡，但不以高阶谐波振荡。在偏好方向运动后有延长的兴奋，在反偏好方向运动后有延长的抑制，这被称为同符号后反应（SSARs）。这是首次详细报道并模拟了NOT中具有SSARs的神经元的反应特性。使用包括带通时间预滤波器的一系列赖夏特型运动探测器对运动期间及之后的慢速细胞反应进行建模。通过操纵与预滤波器和运动探测器中的时间滤波相关的时间常数，该模型可以准确模拟运动期间的振荡行为和SSARs。将慢速细胞的SSARs与先前描述的方向选择性神经元的SSARs进行比较，后者通常在偏好或反偏好方向运动后分别表现出短暂的抑制或兴奋。在眼动控制的背景下讨论了慢速细胞可能的功能作用。
