International Journal of Comparative Psychology

The present review is concerned with the biological role(s) exerted by Growth Factor (GF) protein molecules in adult rodents. In fact, despite the increasing amount of papers published in the last two-three decades about the physiological roles played by Nerve GF and Epidermal GF (as well as by related polypeptide molecules) on the ontogenesis of rodent peripheral and central nervous systems, very little attention has been given to adult regulations involving these two factors. We here report about our studies concerning the biological significance of the huge quantity of NGF stored in the submaxillary salivary glands of the adult male mouse. When released into the bloodstream as a result of psychosocial stress, salivary NGF affects peripheral nervous structures (chromaffine cells and ganglia) and peritoneal mast-cells. Following psychosocial stress, NGF production is enhanced in specific hypothalamic zones. Adult regulations regarding the concomitant EGF release from salivaries are also discussed.

Because woodlice ( Porcellio scaber and pillbugs ( Eluma purpurascens ) that traveled closer to the outer wall of alleys both before as well as after a 90° forced turn subsequently made sharper free turns in the opposite direction, it seemed possible that a quantitative relationship existed between tactile stimulation arising from wall contact and free-turn behavior However, on emerging from straight runways, without any forced turns, pillbugs turned at sharper angles than woodlice but there was no relationship between the size of a turn and amount of wall contact apart from a very minor one for woodlice only. It was concluded that tactile stimuh played a negligible part in turn alternation of either species thereby supporting involvement of proprioceptive cues. By requiring woodlice to negotiate a forced turn lined with glass on the outer half of the floor, it became apparent that their alternation was determined by proprioceptive feedback from bilaterally asymmetrical leg movements rather than distortion of body segments.

In a series of studies undertaken to determine the conditions under which naive house mice (observers) develop preferences for foods eaten by recently-fed conspecifics (demonstrators), we found that observer mice exhibited enhanced preference for a food following interaction with either a healthy or an ill recently-fed demonstrator that had eaten that food. We also found that house mice developed an enhanced preference for a food after exposure to an anesthetized conspecific demonstrator powdered with that food, but not after exposure to a cotton-batting, conspecific-sized surrogate powdered with the same food. Results of other studies have indicated that, for both rats and mice, the presence in a food of carbon disulfide (a substance found on the breath of rats) increases preference for a carbon-disulfide-contaminated food. taken together, the parallels between Norway rats and house mice in social learning processes suggest homologous rather than analogous systems of communication about distant foods in these two murid rodents.

Several experiments have shown that engaging in territorial singing is an appetitive and reinforcing activity in gibbons. The present study examined whether the strength of this behavior would vary with changes in motivational conditions in the same manner as does the strength of the consummatory behavior associated with other reinforcers. The subjects were a fully accommodated pair of siamangs. Following baseline. (A" duration = 34.33 min), song-bout durations were observed under low motivation (X = 20.33 min), then high motivation (X= 36.16 min), then low (Z= 22.67 min), then high (X = 32.50 min). Six song bouts were observed under each condition. In the high motivation condition, 5-6 days intervened between song bouts; in the low motivation condition, song bouts were separated by 2 days. Each change in motivation was accompanied by a significant change in song-bout duration (Mann-Whitney t/ tests; p's < .01 ). Findings are related to a general conception of species-typical behavior as a source of reinforcement.