Combination operant conditioning--liquid nitrogen immersion chamber for studying neurotransmitter systems and...

Studies of neurochemical events associated with behavior require a method of tissue fixation that is rapid and does not itself produce neurochemical changes. An apparatus is described that permits immediate immersion of an unrestrained behaving animal into liquid nitrogen. This method of tissue fixation has the greatest versatility for studying multiple neurotransmitter systems. In addition to the measurement of neurotransmitter content and turnover, investigation of neurotransmitter receptors, enriched nerve ending fractions and enzyme activities are possible. The operant conditioning-liquid nitrogen immersion chamber described here can be used for studying these neurotransmitter systems as they relate to animal's responding on operant schedules of reinforcement.