Developmental Psychobiology

Dumas, Theodore C.

doi: 10.1002/dev.20011pmid: 15229871

Development of the hippocampus is not entirely preprogrammed; its structure and function are sensitive to postnatal experience. For instance, neonatal handling/exposure to novelty and peripubertal environmental enrichment enhance hippocampal function and related memory abilities. However, these complex environmental manipulations make it difficult to deduce the primary stimuli that drive more rapid hippocampal maturation, and few experiments have studied the neural mechanisms that support the behavioral modifications. To address these issues, I performed early eyelid opening in rat pups and examined developmental alterations in exploration of a Y‐maze and in synaptic transmission measured in hippocampal slices. Early eyelid opening accelerated development of spontaneous alternation. Additionally, early eyelid opening promoted more rapid remodeling of afferent input to the dentate gyrus and area CA1 as well as earlier maturation of perforant path synaptic physiology. These findings implicate visual input as an extrinsic factor that drives hippocampal development and the emergence of hippocampal‐dependent behavior. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 45: 1–9, 2004.

Kennedy, Amy E.; Rubin, Kenneth H.; D. Hastings, Paul; Maisel, Beth

doi: 10.1002/dev.20013pmid: 15229872

The longitudinal relations between physiological markers of child emotion regulation and maternal parenting practices were examined from 2 to 4 years of age. At Time 1, cardiac vagal tone was assessed for one hundred four 2‐year‐olds (54 females); their mothers completed an assessment of parenting styles. Two years later, at Time 2, 84 of the original participants were reassessed on measures of cardiac vagal tone and parenting style. Results indicated both baseline cardiac vagal tone and maternal parenting practices to be stable from 2 to 4 years of age. Children's cardiac vagal tone predicted specific parenting practices from the toddler to preschool years. Further, child cardiac vagal tone moderated maternal restrictive‐parenting practices from 2 to 4 years of age; mothers of children who were highly or moderately physiologically dysregulated were more likely to report restrictive parenting practices at both 2 and 4 years of age. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 45: 10–21, 2004.

Smith, Anne; Zelaznik, Howard N.

doi: 10.1002/dev.20009pmid: 15229873

Adults produce rapid, interleaved sequences of speech sounds by controlling the relative motions in time and space of the oral articulators. The control and coordination of these effectors appear to be automatic, effortless, and usually error free. If speech production is viewed within the framework of classical motor control theories, we can infer that adults have organized functional synergies (consistent patterns of activation of muscle collectives) that act as stable subunits. In this study, the development of these stable functional synergies is examined. Motion of the upper lip, lower lip, and jaw was recorded during sentence production in 180 children and adults (aged 4–22 years). Two indices of oral motor coordination were computed, which reflect the degree of trial‐to‐trial consistency in intereffector relationships and thus the stability of the underlying functional synergies. Major findings are: (a) The time course of development for speech motor coordination is protracted, (b) speech motor control processes are not adultlike until after age 14 years for both females and males, (c) boys (until age 5 years) show a slower maturational course of speech motor development, and (d) late childhood (the 7‐ to 12‐year period) is characterized by a plateau in the development of these coordinative synergies for speech production. We posit that multiple factors are likely to contribute to the protracted development of oral motor coordination for speech, including maturation of components of the motor system itself and maturation of the brain subsystems for language processing. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 45: 22–33, 2004.

Goodwin, Gregory A.; Yacko, Holly

doi: 10.1002/dev.20012pmid: 15229874

As infant rats approach weaning, they must overcome their infantile attraction to the home nest and prepare to leave its safety to forage for food. Although nutritive needs may help to motivate pups to make this bold move, a newly emerging exploratory motive also may play a role. Three experiments are reported here which examine age‐related changes in the exploratory motive. In the first experiment, preferences for a novel side over a familiar side of a two‐sided testing chamber were examined in postnatal Days 15 (P15), 17 (P17), 19 (P19), and 21 (P21) rat pups. Subjects did not prefer to explore the novel side until P19. In the same test, no preference for a novel object was observed at any of the ages tested, suggesting that this preference, which is expressed in adulthood, does not emerge until a later age; however, additional studies are needed to verify this. In the second experiment, P15 subjects demonstrated their ability to discriminate the two sides of the testing chamber in a novelty‐induced locomotion test. In the third experiment, the presence of a home‐nest‐associated object was shown to inhibit exploration of novel context in P15, but not P21, subjects. These data suggest that home nest egression may be more the consequence of the declining attractiveness of the home nest than of a growing exploratory motive. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 45: 34–48, 2004.

Alberts, Jeffrey R.

doi: 10.1002/dev.20010pmid: N/A