Centrifugal innervation modulates visual activity of tectal cells in pigeons.
Centrifugal modulation of visual responsiveness of tectal cells by the isthmo-optic nucleus (ION) through the retina was studied in homing pigeons. Visual activity evoked by computer-generated stimuli was reduced by an average of 59% in tectal cells whose receptive fields (RFs) either overlapped with, or were close to, those of isthmo-optic cells whose activity was blocked by the injection of lidocaine through micropipettes. Activity usually recovered to 87% of pre-drug controls in 8-17 min (average 12.3 min) after stopping lidocaine injections. Those tectal cells whose RFs were far from those of ION cells did not show clear-cut changes in their visual responsiveness to isthmo-optic lidocaine application. The spatial relationship between receptive fields of tectal and isthmo-optic cells, saline controls, as well as the specificity, reproducibility and reversibility of effects of ION-injected lidocaine on tectal activity, show that this chemical action is pharmacological, not toxicological. Neuronal circuitry underlying centrifugal modulation of tectal activity by isthmo-optic cells is discussed.
Li
J L
JL
Laboratory for Visual Information Processing, Institute of Biophysics, Academia Sinica, Beijing, China.
Xiao
Q
Q
Fu
Y X
YX
Wang
S R
SR
D000200:Action Potentials; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D010856:Columbidae / Q000502:physiology*; D005260:Female; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009900:Optic Nerve / Q000187:drug effects / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D013477:Superior Colliculi / Q000187:drug effects / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
D000779:Anesthetics, Local; D008012:Lidocaine