Conditioned cardiac and behavioral response topography to an olfactory CS dissociates with age

Infant rats are more likely than adolescents to orient differentially to Amodal (intensity-based) features of single-element and compound stimuli

“…There was no statistical difference in response variance between 15-and 17-day-olds. Similar ontogenetic differences in response variance have been observed in other assessments of cardiac orienting (Kraebel, Vizvary, Heron, & Spear, 1998) and with conditioned cardiac responding (Hunt, Hess, & Campbell, 1997), as well as with behavioral response measures (Wenger & McKinzie, 1996). The specific cause of greater response variance with periadolescents in the current study is unclear, although Hunt et al (1997) suggested that this age may represent a transition in autonomic functioning, with some periadolescents responding in a juvenile manner and others responding in a more adultlike manner.…”

Inhibition of the expression of conditioned cardiac responses in the developing rat

“…The electrode assembly was made from a Winchester subminiature connector (Model SM2S) with two 7-cmlong, Teflon-coated, stainless-steel leads (Model AS636, Cooner Wire Co.). The electrode assembly and the surgery required for implantation have been described in detail elsewhere (Hunt, Hess, & Campbell, 1997;Richardson, Siegel, & Campbell, 1988). For the recording of heart rate, a Winchester subminiature connector (Model SM2P) with lead wires (32-ga, Model 2840/7, Alpha Wire Co.) was attached to the implanted electrode.…”

Retention of conditioned autonomic and behavioral responses in preweanling rats: Forgetting and reinstatement

“…The US was a I-sec 0.6-mA electric shock delivered through the grid floor. The CS was a 30-sec presentation of amyl acetate (0.5 ml amyl acetate dissolved in 40 ml water), delivered using an olfactometer system that has been described in detail elsewhere (Hunt et al, 1997;Sananes et al, 1988). An air stream remained on at all times and was used to maintain temperature in the chamber at 30°C.…”

“…Recently, Hunt, Hess, and Campbell (1997) reported an ontogenetic change in the form ofconditioned responding to an olfactory conditioned stimulus (CS) paired with a footshock unconditioned stimulus (US). Both heart rate (HR) and somatomotor responses to this CS differed as a function ofthe age oftraining.…”

“…An alternative explanation for the divergent conditioned responses (CRs) observed by Hunt et al (1997) focuses on age differences in the contribution of context conditioning. The preweanlings in that study exhibited more freezing in the context in which CS-US pairings occurred than did the adults.…”