Systematic temporal variation in the rate of spontaneous eye blinking in human infants.

The rate of spontaneous eye blinking, a putative index of central dopamine activity based on neuropharmacological and clinical research, has been linked to cognitive activity and behavioral state. Although many species have been studied, few researchers have examined spontaneous eye blinking in human infants. Human infants between 10 and 12 weeks of age were observed before, during, and after a feeding or during attention to visual stimuli.

Spontaneous eye blinking in human infants: a review.

Spontaneous eye blinking has been studied in clinical and neuropharmacological research in adult humans and nonhuman primates as a putative index of central dopamine system activity. One purpose of this review is to provide a general overview of the research on spontaneous eye blinking with an emphasis on the relationship between spontaneous eye blinking and central dopamine systems. We suggest that the body of research from human (adults, children, and infants) and nonhuman primates supports the continued empirical investigation of spontaneous eye blinking in human infants.

Classical conditioning in the rat fetus. III. Retention, extinction, and re-activation of the conditioned response (CR).

A single paired presentation of an artificial nipple (conditioned stimulus, CS) and milk (unconditioned stimulus, US) resulted in classical conditioning. When re-exposed to the artificial nipple CS after conditioning, fetuses showed fewer oral grasp responses compared to control fetuses exposed to the milk (US) and artificial nipple (CS) in an unpaired fashion. The reduction in oral grasping was evident when the test of oral grasping was administered 18 min after conditioning but not 21 to 30 min after conditioning (Experiments 1a and 1b).

Early experience with the artificial nipple.

The present study examined the newborn pup's responsiveness to artificial nipples that differed in length and width. In a series of experiments, pups were: exposed to a long (5.0 mm), thin (1.

Classical conditioning in the rat fetus: temporal characteristics and behavioral correlates of the conditioned response.

This study examined the temporal characteristics and behavioral correlates of the conditioned response (CR) following classical conditioning of the embryonic Day 20 (E20 rat fetus). The conditioning procedure involved pairing of an artificial nipple (the CS) with an infusion of milk (the US) to establish classical conditioning. The test for classical conditioning involved measurement of a stimulus-evoked facial wiping response in a classical conditioning test.

Classical conditioning in the rat fetus: involvement of mu and kappa opioid systems in the conditioned response.

When the Embryonic Day 20 (E20) rat fetus is given a conditioning trial involving a paired presentation of an artificial nipple (the conditioned stimulus; CS) with an intraoral infusion of milk (the unconditioned stimulus; US), it shows evidence of classical conditioning when again exposed to the CS during a test trial. Specifically, the fetus shows fewer oral grasp responses (the conditioned response; CR) when continuously presented with the artificial nipple. The present study further investigated this classically conditioned reduction in oral grasping.

Cyclic motor activity in the fetal rat (Rattus norvegicus).

Rat fetuses were observed on Day 20 of gestation using a technique that permits direct observation of fetal behavior. The resulting time series was analyzed to assess cyclic organization in fetal movement. Fetal activity did not occur randomly but showed significant cyclic variation with a mean frequency of 0.