Vibrissae-evoked behavior and conditioning before functional ontogeny of the somatosensory vibrissae cortex.
The following experiments determined that the somatosensory whisker system is functional and capable of experience-dependent behavioral plasticity in the neonate before functional maturation of the somatosensory whisker cortex. First, unilateral whisker stimulation caused increased behavioral activity in both postnatal day (P) 3-4 and P8 pups, whereas stimulation-evoked cortical activity (14C 2-deoxyglucose autoradiography) was detectable only in P8 pups. Second, neonatal rat pups are capable of forming associations between whisker stimulation and a reinforcer. A classical conditioning paradigm (P3-P4) showed that the learning groups (paired whisker stimulation-shock or paired whisker stimulation-warm air stream) exhibited significantly higher behavioral responsiveness to whisker stimulation than controls. Finally, stimulus-evoked somatosensory cortical activity during testing [P8; using 14C 2-deoxyglucose (2-DG) autoradiography] was assessed after somatosensory conditioning from P1-P8. No learning-associated differences in stimulus-evoked cortical activity were detected between learning and nonlearning control groups. Together, these experiments demonstrate that the whisker system is functional in neonates and capable of experience-dependent behavioral plasticity. Furthermore, in contrast to adult somatosensory classical conditioning, these data suggest that the cortex is not required for associative somatosensory learning in neonates.
Landers
M S
MS
Department of Zoology, University of Oklahoma, Norman, Oklahoma 73019, USA.
Sullivan
R M
RM
D000818:Animals; D000831:Animals, Newborn; D000963:Antimetabolites / Q000493:pharmacokinetics; D001245:Association Learning / Q000502:physiology; D001522:Behavior, Animal / Q000502:physiology*; D003213:Conditioning, Psychological / Q000502:physiology*; D003847:Deoxyglucose / Q000493:pharmacokinetics; D004597:Electroshock; D005260:Female; D006358:Hot Temperature; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology; D010812:Physical Stimulation; D051381:Rats; D020318:Rats, Long-Evans; D013003:Somatosensory Cortex / Q000502:physiology*; D014738:Vibrissae / Q000294:innervation / Q000502:physiology*
D000963:Antimetabolites; D003847:Deoxyglucose