Electroretinogram components of the ocellus of the adult cabbage looper moth Trichoplusia ni

The electroretinogram (ERG) of the adult cabbage looper (Trichoplusia ni) ocellus has been studied by extracellular recording methods. Using white light stimulation, the ERG was found to have four components, two of which differ from those of ocelli previously studied. Here component 3 is an excitatory post-synaptic potential (EPSP) and component 4 is an excitatory spike discharge from the ocellar second-order neurons. The excitatory nature of these components has been verified by two experiments. In a light adaptation experiment decreased stimulus intervals caused a reduction in the number of excitatory spikes. In an experiment with the anticholinesterase tetraethylpyrophosphate (TEPP), treatment of the preparation abolished the excitatory spike discharge and reduced the magnitude of the EPSP.