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Cools R.,Radboud University Nijmegen | Miyakawa A.,University of California at Berkeley | Sheridan M.,Harvard University | Sheridan M.,Developmental Medicine Center | D'Esposito M.,University of California at Berkeley
Brain | Year: 2010

We investigated the role of dopamine in working memory by examining effects of withdrawing dopaminergic medication in patients with Parkinson's disease. Resistance to distraction during a delayed response task was abnormally enhanced in Parkinson's disease patients OFF medication relative to controls. Conversely, performance on a backward digit span test was impaired in these same Parkinson's disease patients OFF medication. Dopaminergic medication reinstated susceptibility to distraction and backward digit span performance, so that performance of Parkinson's disease patients ON medication did not differ from that of controls. We hypothesize that the enhanced distractor resistance and impaired backward digit span in Parkinson's disease reflects low dopamine levels in the striatum, and perhaps upregulated frontal dopamine levels. Dopaminergic medication may reinstate distractibility by normalizing the balance between striatal and prefrontal dopamine transmission.

McLaughlin K.A.,University of Washington | Sheridan M.A.,Developmental Medicine Center | Sheridan M.A.,Harvard University | Mendes W.B.,University of California at San Francisco
Psychosomatic Medicine | Year: 2014

Objective: Disruptions in stress response system development have been posited as mechanisms linking child maltreatment (CM) to psychopathology. Existing theories predict elevated sympathetic nervous system reactivity after CM, but evidence for this is inconsistent. We present a novel framework for conceptualizing stress reactivity after CM that uses the biopsychosocial model of challenge and threat. We predicted that in the context of a social-evaluative stressor, maltreated adolescents would exhibit a threat pattern of reactivity, involving sympathetic nervous system activation paired with elevated vascular resistance and blunted cardiac output (CO) reactivity.Methods: A sample of 168 adolescents (mean age =14.9 years) participated. Recruitment targeted maltreated adolescents; 38.2% were maltreated. Electrocardiogram, impedance cardiography, and blood pressure were acquired at rest and during an evaluated social stressor (Trier Social Stress Test). Pre-ejection period (PEP), CO, and total peripheral resistance reactivity were computed during task preparation, speech delivery, and verbal mental arithmetic. Internalizing and externalizing symptoms were assessed.Results: Maltreatment was unrelated to PEP reactivity during preparation or speech, but maltreated adolescents had reduced PEP reactivity during math. Maltreatment exposure (F(1,145) = 3.8-9.4, p =.053-<.001) and severity (β = -0.10-0.12, p =.030-.007) were associated with significantly reduced CO reactivity during all components of the stress task and marginally associated with elevated total peripheral resistance reactivity (F(1,145) = 3.8-9.4; p =.053-<.001 [β = 0.07-0.11] and p =.11-.009, respectively). Threat reactivity was positively associated with externalizing symptoms.Conclusions: CM is associated with a dysregulated pattern of physiological reactivity consistent with theoretical conceptualizations of threat but not previously examined in relation to maltreatment, suggesting a more nuanced pattern of stress reactivity than predicted by current theoretical models. Copyright © 2014 by the American Psychosomatic Society.

Balas B.,Developmental Medicine Center
Developmental Science | Year: 2010

Newborn infants appear to possess an innate bias that guides preferential orienting to and tracking of human faces. There is, however, no clear agreement as to the underlying mechanism supporting such a preference. In particular, two competing theories (known as the 'structural' and 'sensory' hypotheses) conjecture fundamentally different biasing mechanisms to explain this behavior. The structural hypothesis suggests that a crude '3-dot' representation of face-specific geometry is responsible for the exhibited preference. By contrast, the sensory hypothesis suggests that face preference is the product of several generic visual preferences for qualities like dark/light vertical asymmetry, horizontal symmetry, and high contrast. To complement existing empirical results, the current study describes a computational investigation of how well both proposals actually support face detection in cluttered natural scenes. The results demonstrate that both models are capable of locating faces effectively, but that the model suggested by the 'sensory hypothesis' is more selective than the model suggested by the 'structural hypothesis'. © 2009 The Author. Journal compilation © 2009 Blackwell Publishing Ltd.

Bakare M.O.,Child and Adolescent Unit | Munir K.M.,Developmental Medicine Center
African Journal of Psychiatry (South Africa) | Year: 2011

Background: The universal occurrence of autism spectrum disorders (ASD) was queried about twenty-six years ago. It was thought to occur only in western industrialized countries with high technological development. Over the last decade, knowledge about ASD and its prevalence has been documented as being on the rise in different regions of the world, with most literature coming from the western world - the situation in Africa on aspects of ASD remain unclear. Methods: Literature cited in Pubmed over the last decade on aspects of epidemiology, diagnosis, aetiology and knowledge of ASD in the African context were assessed. Keywords autism, diagnosis, aetiology, knowledge and Africa were variously combined in the literature search. Results: No study specifically addressed the epidemiology of ASD in Africa. One of the two studies that were relevant addressed epidemiology of ASD in Arab countries, though included two Northern African countries. A higher proportion of non-verbal cases of ASD compared to verbal cases was documented in literature coming from Africa. Associated co-morbid disorders included intellectual disability, epilepsy and oculo-cutaneous albinism. Aetiological factors postulated included post-encephalitic infection, genetic and auto-immune factors, and vitamin D deficiency. Knowledge about ASD in Africa was noted to be low. Conclusion: There is a need for epidemiological studies in Africa to define the magnitude of the problem of ASD and the characteristics of children affected by ASD in this region. This would help in planning and might be helpful in answering the question of aetiology of ASD. Policy making needs to be directed at issues of childhood developmental disorders in Africa.

Miller M.,University of California at Berkeley | Sheridan M.,Harvard University | Sheridan M.,Developmental Medicine Center | Cardoos S.L.,University of California at Berkeley | Hinshaw S.P.,University of California at Berkeley
Journal of the International Neuropsychological Society | Year: 2013

We examined decision-making in young adulthood in a follow-up study of females diagnosed with attention-deficit/hyperactivity disorder (ADHD) between 6 and 12 years. Participants with childhood ADHD (n = 114) and matched comparison females (n = 77), followed prospectively for 10 years, performed the Iowa Gambling Task (IGT) at ages 17-25 years. This task assesses preference for high-reward/high-risk chances that result in lower overall gains (disadvantageous decks of cards) compared to low-reward/low-risk chances that result in higher overall gains (advantageous decks of cards). Relative to comparison participants, young adult females with a history of ADHD did not increase their preference for advantageous decks across time blocks, suggesting difficulties in learning to change behavior over the course of the IGT. Overall, childhood diagnoses of ADHD were associated with disadvantageous decision-making in young adulthood. These results extend findings on decision-making in males with ADHD by demonstrating comparable levels of impairment in an all-female sample. Copyright © 2012 The International Neuropsychological Society.

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