Light paired with serotonin mimics the effect of conditioning on phototactic behavior of Hermissenda.
A conditioning procedure consisting of pairing-specific stimulation of the eyes and gravity-detecting statocysts in Hermissenda results in a long-term modification of normal positive phototactic behavior. The learning is expressed by a significant suppression of the initiation of locomotion in the presence of light. We now report that an analogue of the classical conditioning procedure, consisting of light paired with serotonin (5-HT) applied directly to the exposed circumesophageal nervous system of otherwise intact animals, mimics the effect of conditioning on long-term changes in phototactic behavior. The effect of the conditioning analogue on behavior shows some specificity with 5-HT since light paired with dopamine or octopamine does not significantly affect phototactic behavior. The conditioning analogue exhibits pairing specificity since unpaired light and 5-HT and 5-HT applied in the dark do not produce behavioral suppression. Animals that initially received unpaired light and 5-HT do show behavioral suppression after receiving paired light and 5-HT. These results indicate that light (the conditioned stimulus) paired with the putative transmitter of the unconditioned stimulus pathway (5-HT) is sufficient to produce long-term phototactic suppression.
Crow
T
T
Forrester
J
J
D000704:Analysis of Variance; D000818:Animals; D001245:Association Learning; D003214:Conditioning, Classical; D008027:Light; D008124:Locomotion; D008974:Mollusca / Q000502:physiology*; D010786:Photoreceptor Cells / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology*
D012701:Serotonin