Spatial Summation Processes in Visually Driven Neurons of Cat\u27s Pretectal Region

The spatial summation processes of single neurones of cat\u27s 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

Responses of Cat\u27s Dorsal Hippocampal Neurones to Moving Visual Stimuli

Response properties of visually driven neurones in the cat\u27s hippocampal region were investigated. Out of 688 single cells observed 181 (26%) were visually driven. Ocular dominance was determined for 147 of those cells, 90 of which were driven only by the contralateral eye, 20 were driven exclusively by ipsilateral eye and 37 neurones could be activated by both eyes. Receptive field boundaries were outlined for 157; 152 of those neurones were movement-sensitive, and 125 neurones were sensitive to stationary stimuli. A small group of neurones (13%) showed more pronounced reactions to the vertical direction of motion. Some neurones (22%) revealed sensitivity to the shape and size of the applied visual stimuli. These results confirmed earlier data indicating that visually driven neurones in hippocampal region possess complex properties. They are probably involved in a higher level of visual information processing

Responses of Cat\u27s Dorsal Hippocampal Neurones to Moving Visual Stimuli

Response properties of visually driven neurones in the cat\u27s hippocampal region were investigated. Out of 688 single cells observed 181 (26%) were visually driven. Ocular dominance was determined for 147 of those cells, 90 of which were driven only by the contralateral eye, 20 were driven exclusively by ipsilateral eye and 37 neurones could be activated by both eyes. Receptive field boundaries were outlined for 157; 152 of those neurones were movement-sensitive, and 125 neurones were sensitive to stationary stimuli. A small group of neurones (13%) showed more pronounced reactions to the vertical direction of motion. Some neurones (22%) revealed sensitivity to the shape and size of the applied visual stimuli. These results confirmed earlier data indicating that visually driven neurones in hippocampal region possess complex properties. They are probably involved in a higher level of visual information processing

Spatial Summation Processes in Visually Driven Neurons of Cat\u27s Pretectal Region

The spatial summation processes of single neurones of cat\u27s 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