Photoreceptor encoding of supersaturating light stimuli in salamander retina.
In the dark-adapted salamander retina, spikes could be elicited from rods under normal physiological conditions. Spike activity was observed in rods during the recovery phase of the response to saturating light. These action potentials were calcium spikes, blocked by cadmium and L-type calcium channel blockers. In response to light stimuli that saturate the rod peak response, calcium action potentials occurred with a delay that depended on light intensity, with stronger light increasing spike latency. Therefore, these spikes encode rod visual information at light intensities beyond rod saturation. Postsynaptic currents of similar time course were observed in second and third order neurones. Since rods exposed to brighter light stimuli produced more delayed spike activity, these signals might contribute to negative afterimages.
Xu
Jian Wei
JW
Department of Physiology and Biophysics, University at Buffalo, 124 Sherman Hall, Buffalo, NY 14214, USA.
Hou
Mingli
M
Slaughter
Malcolm M
MM
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000221:Adaptation, Ocular / Q000187:drug effects / Q000502:physiology*; D000360:Afterimage / Q000502:physiology*; D000557:Ambystoma; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000502:physiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D008027:Light; D009475:Neurons, Afferent / Q000502:physiology; D024681:Potassium Channels, Calcium-Activated / Q000502:physiology; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D013997:Time Factors
D002121:Calcium Channel Blockers; D024681:Potassium Channels, Calcium-Activated; D002104:Cadmium; D002118:Calcium