Grigorian G G, Harutiunian-Kozak B A, Kazarian A L, Hekimian A A, Markarian T M, Kozak J A
Laboratory of Physiology of Sensory Systems, National Academy of Sciences of Armenia, Erevan.
Acta Neurobiol Exp (Wars). 1994;54(4):321-33.
The spatial summation processes of single neurones of cat's pretectal region were investigated with moving and stationary visual stimuli. The results indicate that the majority of the investigated neurones changed their responses essentially at the gradual increase of size of the applied stimuli (i.e. showed negative or positive summation). Particularly, direction non-sensitive neurones showed symmetrical changes of spatial summation curves in response to two opposite directions of movement. By contrast, in some direction sensitive neurones different characteristics of responses for the two opposite directions of movement were observed. Thus the number of discharges in the responses to the preferred direction could increase or decrease at the gradual increase of the moving stimulus size, while the responses to the null direction could remain stable or vice versa. The same was observed for the "ON" and "OFF" responses in the ON-OFF neurones. Thus, it appears that the pattern of responses of a given neurone to different directions of movement and to the "on" and "off" periods of stationary stimulation are shaped by independent mechanisms.
利用移动和静止视觉刺激研究了猫顶盖前区单个神经元的空间总和过程。结果表明，大多数被研究的神经元在施加刺激大小逐渐增加时，其反应基本发生变化（即表现出负总和或正总和）。特别是，方向不敏感神经元在对两个相反运动方向的反应中，空间总和曲线呈现对称变化。相比之下，在一些方向敏感神经元中，观察到对两个相反运动方向的反应具有不同特征。因此，在移动刺激大小逐渐增加时，对偏好方向反应中的放电次数可能增加或减少，而对零方向的反应可能保持稳定，反之亦然。在开-关神经元的“开”和“关”反应中也观察到同样情况。因此，给定神经元对不同运动方向以及对静止刺激的“开”和“关”时段的反应模式似乎是由独立机制塑造的。
