Classical conditioning in the fetal rat with a long delay between presentation of CS and US.
A single paired presentation of the artificial nipple and milk results in classical conditioning of changes in perioral responsiveness in the E20 rat fetus. This classical conditioning is evidenced by a reduction in responding to perioral tactile stimulation. The results of Experiment 1 confirmed the specificity of milk as an unconditioned stimulus to support classical conditioning. Experiment 2 demonstrated that single-trial classical conditioning with the artificial nipple CS and milk US was possible with a delay of 30 s between nipple and milk presentations. Further, measurements of fetal motor behavior during the delay between CS and US presentations indicated that a single 15-s presentation of the artificial nipple increased movements of the mouth for 30 s after removal of the artificial nipple. Experiment 3 demonstrated that three exposures to the artificial nipple prolonged the expression of mouthing for up to 120 s and made possible single trial classical conditioning with a delay of 120 s between CS and US presentations. The capacity of the fetal CNS to maintain a "behavioral trace" for an ecologically important stimulus, such as the nipple, could have adaptive significance in the early development of motivated behavior.
Varlinskaya
E I
EI
Department of Psychology, Binghamton University-SUNY 13902, USA.
Petrov
E S
ES
Simonik
D K
DK
Smotherman
W P
WP
D000818:Animals; D001245:Association Learning; D003214:Conditioning, Classical; D005260:Female; D005333:Fetus; D005865:Gestational Age; D008297:Male; D011939:Mental Recall; D008892:Milk; D009042:Motivation; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D013391:Sucking Behavior