John Colombo

Habituation revisited: an updated and revised description of the behavioral characteristics of habituation.

The most commonly cited descriptions of the behavioral characteristics of habituation come from two papers published almost 40 years ago [Groves, P. M., & Thompson, R. F. (1970). Habituation: A dual-process theory. Psychological Review, 77, 419-450; Thompson, R. F., & Spencer, W. A. (1966). Habituation: A model phenomenon for the study of neuronal substrates of behavior. Psychological Review, 73, 16-43]. In August 2007, the authors of this review, who study habituation in a wide range of species and paradigms, met to discuss their work on habituation and to revisit and refine the characteristics of habituation. This review offers a re-evaluation of the characteristics of habituation in light of these discussions. We made substantial changes to only a few of the characteristics, usually to add new information and expand upon the description rather than to substantially alter the original point. One additional characteristic, relating to long-term habituation, was added. This article thus provides a modern summary of the characteristics defining habituation, and can serve as a convenient primer for those whose research involves stimulus repetition.

Towards Establishing Dietary Reference Intakes for Eicosapentaenoic and Docosahexaenoic Acids

There is considerable interest in the impact of (n-3) long-chain PUFA in mitigating the morbidity and mortality caused by chronic diseases. In 2002, the Institute of Medicine concluded that insufficient data were available to define Dietary Reference Intakes (DRI) for eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), noting only that EPA and DHA could contribute up to 10% toward meeting the Adequate Intake for alpha-linolenic acid. Since then, substantial new evidence has emerged supporting the need to reassess this recommendation. Therefore, the Technical Committee on Dietary Lipids of the International Life Sciences Institute North America sponsored a workshop on 4-5 June 2008 to consider whether the body of evidence specific to the major chronic diseases in the United States--coronary heart disease (CHD), cancer, and cognitive decline--had evolved sufficiently to justify reconsideration of DRI for EPA+DHA. The workshop participants arrived at these conclusions: 1) consistent evidence from multiple research paradigms demonstrates a clear, inverse relation between EPA+DHA intake and risk of fatal (and possibly nonfatal) CHD, providing evidence that supports a nutritionally achievable DRI for EPA+DHA between 250 and 500 mg/d; 2) because of the demonstrated low conversion from dietary ALA, protective tissue levels of EPA+DHA can be achieved only through direct consumption of these fatty acids; 3) evidence of beneficial effects of EPA+DHA on cognitive decline are emerging but are not yet sufficient to support an intake level different from that needed to achieve CHD risk reduction; 4) EPA+DHA do not appear to reduce risk for cancer; and 5) there is no evidence that intakes of EPA+DHA in these recommended ranges are harmful.

Infant cognition : predicting later intellectual functioning

Infant Intelligence Tests Past and Prologue Individual Differences in Infant Visual Attention Selective Looking in Infants Individual Differences in Infant Learning and Memory Summary and Conclusions

DHA supplementation and pregnancy outcomes

BACKGROUND Observational studies associate higher intakes of n-3 (omega-3) long-chain polyunsaturated fatty acids (LCPUFAs) during pregnancy with higher gestation duration and birth size. The results of randomized supplementation trials using various n-3 LCPUFA sources and amounts are mixed. OBJECTIVE We tested the hypothesis that 600 mg/d of the n-3 LCPUFA docosahexaenoic acid (DHA) can increase maternal and newborn DHA status, gestation duration, birth weight, and length. Safety was assessed. DESIGN This phase III, double-blind, randomized controlled trial was conducted between January 2006 and October 2011. Women (n = 350) consumed capsules (placebo, DHA) from <20 wk of gestation to birth. Blood (enrollment, birth, and cord) was analyzed for red blood cell (RBC) phospholipid DHA. The statistical analysis was intent-to-treat. RESULTS Most of the capsules were consumed (76% placebo; 78% DHA); the mean DHA intake for the treated group was 469 mg/d. In comparison with placebo, DHA supplementation resulted in higher maternal and cord RBC-phospholipid-DHA (2.6%; P < 0.001), longer gestation duration (2.9 d; P = 0.041), and greater birth weight (172 g; P = 0.004), length (0.7 cm; P = 0.022), and head circumference (0.5 cm; P = 0.012). In addition, the DHA group had fewer infants born at <34 wk of gestation (P = 0.025) and shorter hospital stays for infants born preterm (40.8 compared with 8.9 d; P = 0.026) than did the placebo group. No safety concerns were identified. CONCLUSIONS A supplement of 600 mg DHA/d in the last half of gestation resulted in overall greater gestation duration and infant size. A reduction in early preterm and very-low birth weight could be important clinical and public health outcomes of DHA supplementation. This trial was registered at clinicaltrials.gov as NCT00266825.

n−3 Fatty acids and cognitive and visual acuity development: methodologic and conceptual considerations

Several randomized clinical studies in infants born preterm and at term have explored the effects on visual acuity development of postnatal supplementation with various sources of docosahexaenoic acid (DHA). Higher visual acuity after DHA supplementation is a consistent finding in infants born preterm. For infants born at term, the results are less consistent and are better explained by differences in sensitivity of the visual acuity test (electrophysiologic tests being more sensitive than subjective tests) or by differences in the amount of DHA included in the experimental formula. Differences in the sensitivity of the test may also be relevant in discussions of whether the effects of DHA on visual acuity are transient or persistent. A smaller number of studies have attempted to study the effects of DHA on cognitive development. The major focus of this article is to review the types of methods that have been used to evaluate the effects of DHA on cognition and to provide the rationale for measures that are a better conceptual fit. Research is needed (1) to probe the effects of variable DHA exposure on infant and child development, (2) to measure outcomes that better relate to preschool and school-age cognitive function, and (3) to reinforce, and in some cases demonstrate, links between specific infant and preschool measures of cognitive development. We strongly encourage collaborations with developmental cognitive neuroscientists to facilitate these research goals.

Infant visual habituation.

The use of visual habituation in the study of infant cognition and learning is reviewed. This article traces the history of the technique, underlying theory, and procedural variation in its measurement. In addition, we review empirical findings with respect to the cognitive processes that presumably contribute to habituation, studies of developmental course and long-term prediction, as well as recent attempts to address or explain the phenomenon of visual habituation through the use of mathematical or quantitative models. The review ends with an appeal for a return to the study of habituation per se as a valid measure of infant learning, rather than relegating the phenomenon to its use as a technique for familiarizing infants in procedures testing for discrimination or recognition.

Visual Scanning and Pupillary Responses in Young Children with Autism Spectrum Disorder

Using eye-tracking technology we investigated visual scanning and pupillary responses to face and non-face stimuli in nine children (M = 49.6 months) with Autism Spectrum Disorder (ASD) compared to six mental-age and nine chronological-age matched children. The results revealed a significant decrease in visual scanning to landscapes. In addition, the ASD group showed pupillary constriction to childrens faces, while control groups showed pupillary dilation. Visual scanning responses to landscapes had a negative correlation with the Behavior subscale of the Autism Diagnostic Observation Schedule-Generic for the ASD group. Potential use of these measures as early indicators of ASD is discussed.

The emergence and basis of endogenous attention in infancy and early childhood.

Publisher Summary Attention is a familiar and ubiquitous psychological construct that is widely alluded to in various scientific, clinical, and colloquial domains. Attention also remains as one of the least well-understood cognitive functions. The processes that represent the construct of attention are often said to share a common theme of “selection.” However, the process of selection is complex and depends on a number of subsidiary processes, such as detection, localization, and probably some form of recognition. Advances in the cognitive neuroscience of attention have elucidated the neural pathways by which these processes occur and have lent support to the notion of the existence of many “varieties” of attention. Selection may be accomplished by different, seemingly independent neural substrates and thus, the nature, character, and function of attention during development can be determined by the interaction of different systems at different levels of maturity.

Infant Attention Grows Up: The Emergence of a Developmental Cognitive Neuroscience Perspective:

Visual attention has long been regarded as a tool for studying the development of basic cognitive skills in infancy and early childhood. However, over the past decade, the development of attention in early life has emerged as an important topic of research in its own right. This essay describes recent changes in the methods used to study attention in infancy, and in the nature of inferences about the early development of attention, as both research and theory in the area have become progressively integrated with models of attention from cognitive science and neuroscience.

A method for the measurement of infant auditory selectivity

In two experiments, infants were-presented with varying auditory stimuli contingent upon their fixation to identical but separate visual targets. Differential responses were found in total fixation time to targets on the basis of the auditory stimulus associated with them. This method for assessment of auditory selectivity can be used with infqnts as young as four months of age.