<Originals>Classical conditioning of an eye-stalk withdrawal reflex in crayfish

概要

論文の詳細を見る
Classical conditioning of eye-stalk withdrawal reflex (EWR) was studied in crayfish (Procambarus clarkii). A photic stimulus (conditioned stimulus, CS) applied to the eye was paired with a tactile stimulus (unconditioned stimulus, UCS) to the cephalothorax. The photic stimulus was applied ipsilaterally and the EWR was evoked ipsilaterally by mechanical stimulation of the carapace. When the stimulations were paired, the CS evoked EWR in progressively larger amplitude at each trial. The CSs were classified into two groups ; with and without illumination. The animals were trained by changing the timing of the CS from onset of the light to extinguishing of the light. The time needed to learn the light extinction as CS was shorter than that needed to learn light onset. This meant that light extinction is more important than onset for crayfish. The neuronal connection between these input-output relations is rather simple, and apparently organized for convenience of the reflex. Associative learning in crayfish is a possible model to study a simpler neuronal circuit.