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.

Effects of warmth on newborn rats' motor activity and oral responsiveness to an artificial nipple.

Temperature is a powerful regulator of the behavior and physiology of newborn altricial animals. The effects of warmth on newborn rats' oral responsiveness to suckling stimuli and spontaneous motor activity in a thermoneutral environment were investigated. Newborn rat pups' oral grasp responses to an artificial nipple and overall motor activity were recorded for 18 min.

The first suckling episode in the rat: the role of endogenous activity at mu and kappa opioid receptors.

The present study examined the role of endogenous activity at mu and kappa opioid receptors in attachment to and ingestion of milk from a surrogate nipple in cesarean-delivered newborn rats prior to regular suckling experience. Selective opioid antagonist drugs were injected into the cisterna magna (IC administration) or lateral ventricles (ICV administration). Blockade of endogenous activity at mu opioid receptors by IC administration of the selective antagonist CTOP reduced attachment time and markedly increased disengagements from the nipple.

Milk delivery schedules and stomach preloading alter patterns of suckling behavior by newborn rats on a surrogate nipple.

Newborn rat pups tested before suckling experience attached to and ingested milk from the surrogate nipple. Time attached to the nipple and amount of milk ingested depended on the schedule of milk infusion through the nipple. More frequent milk infusions resulted in more frequent disengagements from the nipple during the test, less time attached to the nipple, and less body weight gain.

Classical conditioning of responses to an artificial nipple in the rat fetus: mu and kappa opioid systems.

The rat fetus exhibits oral grasp responses when presented with an artificial nipple in utero. Preexposure to milk produces a transient decrease in oral grasp responses. The effect of milk on oral grasping is mediated by endogenous activity in brain opioid systems.

Developmental psychobiology: a look back on 30 years.

Developmental Psychobiology publishes papers from the disciplines of psychology, biology, neuroscience, and medicine that contribute to an understanding of behavioral development. Research focuses on development in the embryo/fetus, neonate, juvenile, and adult as well as multidisciplinary research that relates behavioral development to anatomy, physiology, biochemistry, genetics, and evolution. The journal represents a broad phylogenetic perspective on behavioral development by including studies on invertebrates, fish, birds, non-human primates, and humans.

An intrinsic source of behavioral regulation that influences discrete responses to cues important for the initiation of suckling.

The present experiment investigated the relationship between motor activity and oral grasping of an artificial nipple in newborn rats. Pups orally grasped the artificial nipple, and they performed more and longer oral grasps in the latter portion of the nipple presentation. Motor activity was cyclical, and this cyclicity was evident before and during presentation of the artificial nipple.

How the neonatal rat gets to the nipple. II. Changes during development.

In the course of postnatal development, the motor sequence executed by pups in order to attach to the dam's nipple undergoes extensive changes. During the 1st postnatal week, the pup performs a rotation along the longitudinal axis of its trunk to achieve a supine posture under the mother. The pup then crawls on the maternal ventrum while in the supine posture, searching for, finding, and attaching to a nipple.

Sustained attachment to the nipple in the newborn rat depends on experience with the nipple, milk, and the expression of oral grasping.

Newborn rats showed mouthing, licking, and oral grasping when presented with a surrogate nipple. These responses changed after the pup expressed an oral grasp response and experienced milk at the nipple. Newborn pups that ingested milk from the surrogate nipple showed brief oral grasp responses and, when tested 1 hr later, showed sustained attachment to an empty surrogate nipple.

Blood pressure and heart rate in the ovine fetus: ontogenic changes and effects of fetal adrenalectomy.

Ontogenic changes in baseline and 24-h rhythms of fetal arterial blood pressure (FABP) and heart rate (FHR) and their regulation by the fetal adrenal were studied in 18 fetal sheep chronically instrumented at 109-114 days gestation (GA). In the long-term study, FABP and FHR were continuously recorded from 120 days GA to spontaneous term labor (>145 days GA) in five animals. Peak times (PT) and amplitudes (Amp) of cosinor analysis were compared at 120-126, 127-133, and 134-140 days GA.

Endogenous mu opioid systems and suckling in the neonatal rat.

Localized injections of the mu antagonist CTOP into intracisternal (i.c.) or intracerebroventricular (i.

Fetal Behavioral Development: Measurement of Habituation, State Transitions, and Movement to Assess Fetal Well Being and to Predict Outcome.

> Objective: This paper describes the deliberations of an interdisciplinary group of clinical and basic scientists who met at the National Institute of Child Health and Human Development to discuss the potential role of fetal behavior in assessing fetal well being and predicting neonatal outcome. The conference focused on three aspects of fetal behavior: 1) habituation; 2) state transitions; and 3) movement. Methods: The participants consisted of 25 leaders in the fields of obstetrics, perinatal medicine, neonatology, developmental psychobiology, developmental neuroscience, developmental psychology, ethology, and mathematics.

Thermal, olfactory, and tactile stimuli increase oral grasping of an artificial nipple by the newborn rat.

Caesarean-delivered rat pups tested before any suckling experience show oral grasp responses after stimulation with an artificial nipple. Manipulating the sensory stimuli present at the time of testing alters behavioral responses to the nipple. Specifically, when the nipple is warm, when pups are tested in the presence of amniotic fluid or milk odor, or when pups are tested in the presence of a conspecific, oral grasping of the artificial nipple is increased.

Endogenous opioids and the first suckling episode in the rat.

Endogenous activity at opioid receptors affects the appetitive behavior of Caesarean-delivered rat pups during presentation of a surrogate nipple that provides milk. Blockade of opioid receptors by peripheral injection of naloxone has no effect on responses evoked by the surrogate nipple. Similarly, blockade of caudal brain opioid receptors by injection of naloxone into the cisterna magna has no effect on the pup's behavior in response to the surrogate nipple.

Variation in motor activity on different time scales and responsiveness to oral stimulation in the rat fetus.

The near-term rat fetus exhibits brief oral grasp responses to discrete presentations of an artificial nipple. In the present experiment, an artificial nipple was presented to individual fetal subjects 10 times. Five of the presentations were timed to occur when spontaneous fetal motor activity was low and five while activity was high, as determined by the baseline activity for the individual fetus.

The development of nuchal atonia associated with active (REM) sleep in fetal sheep: presence of recurrent fractal organization.

The behavioral state of active or rapid eye movement sleep (REMS) is dominant during fetal life and may play an important role in brain development. One marker of this state in fetal sheep is neck nuchal muscle atonia (NA). We observed burst within burst NA patterns suggestive of recurrent fractal organization in continuous 13 day in utero recordings of NA during the third trimester.

Stimulus contingencies that permit classical conditioning of opioid activity in the rat fetus.

In a prenatal model of classical conditioning, rat fetuses received presentations of an artificial nipple (conditioned stimulus; CS) paired with milk (unconditioned stimulus). Infusion of milk promotes activity in the kappa opioid system of the fetus, but after 2, 3, or 6 pairings with the artificial nipple, milk evoked both kappa and mu opioid activity. The nipple CS has no effect on opioid activity, but after pairing with milk evoked a mu opioid response.

How the neonatal rat gets to the nipple: common motor modules and their involvement in the expression of early motor behavior.

One-day-old rat pups adopt a supine posture before attaching to the mother's nipple. Body rotations performed to reach the nipple occur in a typical kinematic structure. First, the pup rotates along the longitudinal axis of the trunk and lies on its side.

Experimental study of the first suckling episode: rat pups ingest fluids through a surrogate nipple.

The present study reported a new technique in which pups ingested fluids from a surrogate nipple. Cesarean-delivered pups tested before suckling experience showed oral grasp responses and ingested milk from the surrogate nipple. Pups ingested equal amounts of distilled water and milk and rejected saline.