Electrically induced behavior and neural specificity in ground squirrels and dormice

Electrical stimulation of the lateral hypothalamus in 2 species of hibernator, dormice (Glis glis) and ground squirrels (Spermophilus lateralis), suggests that induced behaviors may reflect activation of specific neural systems, rather than merely activation of a single central mechanism interacting with internal and external cues and past experience (prepotency hypothesis). In dormice, the stimulation induced feeding on powdered food; in squirrels it induced either feeding or picking up of food pellets. Consistent with neural specificity in both species were high probabilities of emergence (78-81%) of a behavior during stimulation at an electrode site, with no greater ease of emergence at a second site tested. In squirrels, only 1 of the 2 behaviors emerged at a site, and there was independence between behaviors emerging at contralateral sites. Long-term reliability of the behavior initially observed at an electrode site was 100% despite infradian (dormice) or circannual (squirrels) cycles of body weight and food intake. Some squirrels consistently showed different induced behaviors at contralateral electrode sites throughout their circannual cycle. These observations suggest that feral species are valuable in investigations of mechanisms underlying electrically induced behaviors, and that reevaluation of the prepotency hypothesis may be in order.