Intracellular analysis of directional sensitivity of tectal neurons of the frog.
The directional sensitivity of tectal neurons of the frog was examined by means of in vivo whole cell recording technique. Three kinds of stimulus were applied; (1) diffuse light 'on-off', (2) moving dark spot and (3) light spot given at one dimensional grid points. The first stimulus revealed whether or not retinal 'on-off' (R3) or 'off' (R4) fibers contribute to the response. As reported earlier, the following patterns were found for both light 'on' and light 'off': EPSPs only, IPSPs only or a combination of EPSPs and IPSPs. Four directionally sensitive neurons and three non-directionally sensitive neurons were found using the second stimulus. Using the third stimulus, responses at up to 11 positions separated by 2 degrees or 4 degrees were recorded. By measuring the amplitudes of 'on' and 'off' responses at different times, spatio-temporal receptive fields were composed. Two types of directional sensitivity were found. The response of the first type was composed of exclusively excitatory potentials, but the second type was composed of a combination of excitatory and inhibitory potentials. The spatio-temporal receptive field of the second type showed spatially separated excitatory and inhibitory regions with constant latencies. Such simple spatio-temporal receptive field organization was not found for directional sensitive neurons of the cat visual cortex. The spatio-temporal receptive field organization of the second type of directionally sensitive neuron in the present study is in agreement with striated receptive field found in some of the T5 neurons classified by extracellular unit recording [Frog Neurobiology (1976) 297].
Hoshino
Noriaki
N
Kyushu Institute of Technology, Faculty of Computer Science and Systems Engineering, Department of Biophysical Engineering and Science, Iizuka, 820-8502, Fukuoka, Japan.
Matsumoto
Nobuyoshi
N
D000818:Animals; D015350:Contrast Sensitivity; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005260:Female; D008027:Light; D008297:Male; D008954:Models, Biological; D009068:Movement; D009433:Neural Inhibition; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D010775:Photic Stimulation; D011892:Rana catesbeiana; D011930:Reaction Time / Q000502:physiology; D013477:Superior Colliculi / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*