The thalamic rat: general behavior, operant learning with rewarding hypothalamic stimulation, and effects of amphetamine

In 52 rats the major forebrain areas, including the cortex, hippocampus, striatum, amygdala and septum were bilaterally ablated, resulting in a chronic thalamic preparation. Experiment 1 measured body temperature and motor activity, showing continuous cyclic 10–60 minute rest- activity cycles. Intragastric feeding was followed by periods of quiescence accompanied by hypothermia lasting from 1–5 hrs. Experiment 2 demonstrated sucessful operant conditioning of limb movements in 12 animals by use of rewarding hypothalamic stimulation. Once a response was strengthened by conditioning no extinction could be observed, although the response was modifiable by further conditioning. In Experiment 3 the effects of d-amphetamine were investigated. Amphetamine induced hyperthermia, hyperactivity and stereotyped behaviors, and was found to facilitate primarily the performance of the previously conditioned behavior.