[Responses of neurons in the nucleus isthmi region of the frog to optic nerve stimulation].
Neuronal responses were studied in the nucleus isthmi area of Rana temporaria. The animals were immobilized by diplacine, a curare-like drug. Single neurons in this area had no background activity. After single-pulse electric stimulation of the contralateral optic nerve these neurons discharged as a rule with one action potential only, its minimal latency being 20-110 msc. The latencies decrease significantly when the stimulus intensities were increased from threshold to maximal, indicating development of summation process in the corresponding afferent pathway. Only 14 per cent (7 of 57) of neurons responded to stimuli exciting myelinated optic fibres and not exciting the ummyelinated ones. All the nucleus isthmi neurons discharged with unstable latency; this means that these neurons were excitated not antidromically. The functional role of nucleus isthmi in Anurans is discussed.
D000818:Animals; D001001:Anura; D001931:Brain Mapping; D004558:Electric Stimulation; D008297:Male; D009900:Optic Nerve / Q000502:physiology*; D011896:Rana temporaria; D011930:Reaction Time; D003336:Tectum Mesencephali / Q000502:physiology; D014795:Visual Pathways / Q000033:anatomy & histology / Q000502:physiology*
Reaktsii neĭronov oblasti nucleus isthmi liagushki na razhdrazhenie zritel'nogo nerva