Maturational loss of thermotaxis prevented by olfactory lesions in golden hamster pups (Mesocricetus auratus).

Five-day-old golden hamster pups were tested preoperatively on a thermal gradient, subjected to bilateral or unilateral olfactory bulbectomy or control dorsal cortical removal, and then tested on Days 6-15. Locomotion and rectal or belly temperature were monitored throughout the 2-min test. Control pups became quiescent in the hot end of the gradient on Days 5-7 but after Day 8 chose cooler regions and increased their activity. Both unilaterally and bilaterally bulbectomized pups spent more time in the heat throughout testing. They were also less active and allowed their temperature to rise more rapidly than controls. Percentage of time in the heat was elevated in all bulbectomized pups, although some retained the ability to make an olfactory discrimination. Enhanced thermal behavior is apparently not due to anosmia per se. Altered thermal perception or responsitivity may result from loss of "nonspecific" olfactory projections that normally would mature at the beginning of the second week.