FURTHER STUDIES OF THE CHEMICAL SENSITIVITY OF THE OSCILLATORY POTENTIALS OF THE ELECTRORETINOGRAM (ERG)

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Abstract
The effects of GABA and glycine antagonists on the oscillatory potential (OP) of the mudpuppy ERG were studied. Upon exposing the retina to bicuculline and picrotoxin, blocking agents of the putative inhibitory neurotransmitter GABA, all the OP were selectively abolished. The earlier OP (O1-O3 [1st-3rd OP]) appeared more sensitive to the drug than the later ones (O4-O5). There was no appreciable effect on the range of sensitivity and saturation level of the b-wave. Low concentrations of strychnine, blocking the effect of the putative inhibitory neurotransmitter glycine, produced a selective decrease of the amplitude of the OP. O1 appeared less sensitive to the drug than the later OP. Higher concentrations extinguished all the OP but decreased the suprathreshold amplitude of the b-wave. The OP appear to have a different origin from the b-wave and seem generated by inhibitory feedback circuits within retina. The differential sensitivity of the individual oscillatory peaks imply that chemically different synaptic activities may underlie the individual oscillatory potentials.