A preparation developed by the Principal Investigator for recording intracellular responses from pre- and postsynaptic units of the dragonfly ocellus will be used to study synaptic interactions in this relatively simple eye and relate it to similar situations in the vertebrate retina. A surprising result of anatomical studies was the finding of reciprocal synapses between receptors and between postsynaptic units and receptors. In pharmacological studies, special attention will be paid to the possible role of these reciprocal synapses in transient enhancement. To this end, antidromic stimulation and effects of currents passed intracellularly on both sides of the synapses will be studied.