Developmental differences in temporal patterns and potentiation of isolation-induced ultrasonic vocalizations: influence of temperature variables.
The present study examined the relationship between the thermal environment and core body temperature in producing age-related patterns of ultrasonic vocalizations (USVs). Implanted telemetry devices allowed on-line measurement of core body temperature during an extended period of isolation and after maternal contact, both as a function of age and thermal environment. At 12 or 17 days of age, rat pups were isolated for 30 min in either a cool or a warm environment, returned home for 5 min, and then re-isolated for 10 min. Number of USVs, body temperature, and behavioral activity were measured. During initial isolation in a cool environment, 12-day-olds displayed relatively stable patterns of ultrasounding and body temperature across time whereas older animals showed a time-dependent increase in USV calling and in core temperature. During re-isolation, 12-day-olds potentiated their USV calling at both ambient temperatures while 17-day-olds did not. The overall results suggest a strong dependence between USV calling, core body temperature, and ambient temperature during initial isolation at both ages-a finding in agreement with interpretations of USVs as an acoustic by-product of thermal challenge. In contrast, during re-isolation, USV calls, core body temperature, and ambient temperature functioned independently-a finding in agreement with interpretations of USVs as a representation of an emotional state.
Kraebel
Kimberly S
KS
Center for Developmental Psychobiology, Binghamton University, Binghamton, NY 13902-6000, USA.
Brasser
Susan M
SM
Campbell
James O
JO
Spear
Linda P
LP
Spear
Norman E
NE
D000818:Animals; D000831:Animals, Newborn / Q000523:psychology*; D001143:Arousal; D001833:Body Temperature Regulation; D005260:Female; D008297:Male; D008426:Maternal Deprivation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013686:Telemetry; D014465:Ultrasonics; D014828:Vocalization, Animal