Developmental Psychobiology

It has been hypothesized that reward‐seeking and impulsivity develop along different timetables and have different neural underpinnings, and that the difference in their timetables helps account for heightened risk‐taking during adolescence. In order to test these propositions, age differences in reward‐seeking and impulsivity were examined in a socioeconomically and ethnically diverse sample of 935 individuals between the ages of 10 and 30, using self‐report and behavioral measures of each construct. Consistent with predictions, age differences in reward‐seeking follow a curvilinear pattern, increasing between preadolescence and mid‐adolescence, and declining thereafter. In contrast, age differences in impulsivity follow a linear pattern, with impulsivity declining steadily from age 10 on. Heightened vulnerability to risk‐taking in middle adolescence may be due to the combination of relatively higher inclinations to seek rewards and still maturing capacities for self‐control. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 216–224, 2010

The effects of early‐life trauma and its consequences for the treatment of depression are reviewed. The prevalence and clinical sequelae of early sexual and physical abuse, neglect and parental loss are described. An overview of preclinical studies that help guide clinical research and practice is presented. Human clinical studies on the neurobiological consequences of early trauma are summarized. Moderating factors, such as genetic variation and sex differences, are discussed. The few current treatment outcome studies relevant to this research area are described. Guidance for the management of patients with depression and a history of child abuse and neglect are provided. Most patients who have experienced early traumatic experiences are likely best treated with a combination of psychotherapy and pharmacotherapy. This review is dedicated to the memory of Seymour Levine who pioneered the field of early experience research and to a considerable extent inspired the clinical studies described in this review. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 671–690, 2010.

The behavioral and polygraphic characteristics of wakefulness and sleep were studied in 20 infant rats, 26 kittens, and 25 infant guinea pigs during their first month of postnatal life. In the infant guinea pig, the electrocorticographic (ECoG) patterns of sleep were similar to those of the adult, except for the absence of spindles during the first 3 weeks. In the rat and the cat, states of vigilance were not clearly differentiated in ECoG patterns during the first week; near the 8th day a fast, high amplitude ECoG appeared during paradoxical sleep (PS). The first signs of slow‐wave sleep (SWS) appeared at 11 to 13 days of age in the rat and at 15 to 21 days in the cat. The greater the immaturity of the animal at birth, the greater was the amount of time spent in PS in the perinatal period. In the rat, which was born the most immature, the decrease in the percent time of PS was very rapid: 70 % at birth, it decreased to 12% on the 30th day. In the cat the decrease was slower. In the guinea pig, despite its relative maturity, the percent time of PS at birth was 7%, approximately double that in the adult. The length of extrauterine life as well as the degree of immaturity at birth, played a role in the development of the sleep‐wakefulness cycle.

The characterization of adolescence as a time of “storm and stress” remains an open debate. Intense and frequent negative affect during this period has been hypothesized to explain the increased rates of affective disorders, suicide, and accidental death during this time of life. Yet some teens emerge from adolescence with minimal turmoil. We provide a neurobiological model of adolescence that proposes an imbalance in the development of subcortical limbic (e.g., amygdala) relative to prefrontal cortical regions as a potential mechanism for heightened emotionality during this period. Empirical support for this model is provided from recent behavioral and human imaging studies on the development of emotion regulation. We then provide examples of environmental factors that may exacerbate imbalances in amygdala‐ventrofrontal function increasing risk for anxiety related behaviors. Finally we present data from human and mouse studies to illustrate how genetic factors may enhance or diminish this risk. Together, these studies provide a converging methods approach for understanding the highly variable stress and turmoil experienced in adolescence. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 225–235, 2010

Psychophysical studies of children deprived of early visual experience by dense cataracts indicate that there are multiple sensitive periods during which experience can influence visual development. We note three sensitive periods within acuity, each with different developmental time courses: the period of visually‐driven normal development, the sensitive period for damage, and the sensitive period for recovery. Moreover, there are different sensitive periods for different aspects of vision. Relative to the period of visually driven normal development, the sensitive period for damage is surprisingly long for acuity, peripheral vision, and asymmetry of optokinetic nystagmus, but surprisingly short for global motion. A comparison of results from unilaterally versus bilaterally deprived children provides insights into the complex nature of interactions between the eyes during normal visual development. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 163–183, 2005.

In this article, we provide a critical review of the literature on speech perception and phonological processing in infancy, and in populations with different experiential histories as a window to understanding how the notion of critical periods might apply to the acquisition of one part of language: the sound system. We begin by suggesting the use of the term “optimal period” because (a) both the onset (opening) and offset (closing) of openness to experience is variable rather than absolute and (b) phonological acquisition involves the emergence of a series of nested capabilities, each with its own sensitive period and each best explained at one of several different levels of specificity. In support, we cite evidence suggesting that to fully understand plasticity and commitment in phonological acquisition, it is necessary to consider not only the biological and experiential factors which may contribute to the onset and the offset of openness to experience but also how the sequentially developing parts of phonology constrain and direct development. In summary, we propose a nested, cascading model wherein biology, experience, and functional use each contribute. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 233–251, 2005.

All organisms inherit parents' genes, but many also inherit parents, peers, and the places they inhabit as well. We suggest the term ontogenetic niche to signify the ecological and social legacies that accompany genes. A formal name is needed to give the idea of the inherited environment equal status with its conceptual cognates; nature and nurture. We argue here that increased recognition of the inherited environment facilitates unification efforts within the development sciences by emphasizing the affinity, rather than opposability, of ontogenetic processes.

The development of coordination of leg movements of human infants is discussed from the perspective of dynamic motor theory. Even in the newborn period, leg movements have topographical and temporal organization, but it is global and inflexible. During the first year, limb segments become both disassociated from these global synergies and reintegrated into more complex coalitions. Growthrelated changes in the biodynamic properties of the body segments may be as important as neurological maturation in determining the movement outcomes and may help explain the spurts, regressions, and asymmetries seen in early infancy.

Separation of neonatal rat pups from the dam have been reported to elicit two endocrine responses in the pup: a fall in growth hormone secretion and a rise in corticosterone secretion. However, the temporal, ontogenetic, and behavioral determinants of these responses have not been compared. In the present study, we report that these two responses can be differentiated on each of these criteria. Growth hormone secretion falls repidly immediately upon separation of pups from the dam, while robust rises in corticosterone secretion are delayed for many hours. In addition, growth hormone responses are observed earlier in ontogeny. Finally, active maternal behavior is required for normal growth hormone secretion in 10‐day‐old rat pups, while passive sensory stimuli associated with the dam can significantly reduce the corticosterone response to separation.

A range of basic and applied studies have demonstrated that during the development of the auditory system, early experimental manipulations or clinical interventions are generally more effective than those made later. We present a short review of these studies. We investigated this age‐related plasticity in relation to the timing of cochlear implantation in deaf‐from‐birth children. Cochlear implantation is a standard intervention for providing hearing in children with severe to profound deafness. An important practical question is whether there is a critical period or cutoff age of implantation after which hearing outcomes are significantly reduced. In this article, we present data from prelingually deaf children (mostly congenitally deaf) implanted at ages ranging from 1 to 15 years. Each child was tested with auditory and speech understanding tests before implantation, and at regular intervals up to 8 years postimplantation. We measured the improvement in performance of speech understanding tests in younger implanted children and compared it with the results of those implanted at a later age. We also used a binary partitioning algorithm to divide the data systematically at all ages at implant to determine the optimum split, i.e., to determine the age at implant which best separates performance of early implanted versus later implanted children. We observed distinct age‐of‐implant cutoffs, and will discuss whether these really represent critical periods during development. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 252–261, 2005.