stimulation at a series of points along the floor of the hypothalamus and telencephalon. Twelve points were selected, in 12 different animals. After implantation and a 14-day recovery period, animals were trained to press a lever for chemical stimulation with iproniazid; in this case there was no prior training with electric stimulation.Whereas all animals with ventral hypothalamic pipettes showed a betterthan-chance tendency to press the bar for injection of the chemical, there was a distinct differentiation of rate of selfinjection, depending on placement of the pipette. Pipettes in the posterior hypothalamus gave higher rates of selfinjection than pipettes in the anterior hypothalamus. And high rates of self-injection were also obtained with pipettes in the dorsal preoptic region. These differences agree well with differences with respect to brain area in rate of self-stimulation obtained in earlier experiments with electric stimulation (5).When the injector was turned off, so that bar-pressing no longer produced self-injection, animals continued to press the bar for some time (see Fig. 1), as though no change had been made. This is probably attributable to the high level of the chemical in the brain at these points and to the gradual working down of residual stores in the pipette. Extinction does eventually result from termination of the flow, after a period of about 30 to 45 minutes. Also, when the animal is shifted from an extinction period to a new self-injection period, rate of responding quickly changes from chance levels to rates of about 300 an hour. Thus, it is the chemical reward which sustains the behavior. Injection of serotonin, by itself or immediately after injections of iproniazid, caused the animals to lie down. An animal lying down after injection of serotonin could be brought back to its feet by epinephrine. This, taken together with the tendency of some animals to press the bar for epinephrine, suggests that the exciting and rewarding effects of iproniazid are connected more with epinephrine than with serotonin.From the experiments on self-injection, three main results have been gained. Substantively, we have learned that iproniazid is an excitant of reward functions in this motivational system of the hypothalamus, and that quite probably it has this excitatory function in common with epinephrine. Methodologically, we have validated a technique of self-injection which can now be used to resolve further the problem of the excitatory and inhibitory chemistry of the motivational systems. Finally, from the stimulation at a series of points along the floor of the hypothalamus and telencephalon. Twelve points were selected, in 12 different animals. After implantation and a 14-day recovery period, animals were trained to press a lever for chemical stimulation with iproniazid; in this case there was no prior training with electric stimulation.Whereas all animals with ventral hypothalamic pipettes showed a betterthan-chance tendency to press the bar for injection of the chemical, there was a distinc...
No abstract
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.