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A hallmark symptom of attention-deficit hyperactivity disorder (ADHD) is an excess of motoric behavior or hyperactivity. Methylphenidate (MPH) is known to reduce hyperactivity in individuals with ADHD. Yet little is known about how it alters neural activity and how this relates to its clinical effects. The goal of this study is to examine MPH-induced(More)
One prevalent theory of learning states that dopamine neurons signal mismatches between expected and actual outcomes, called temporal difference errors (TDEs). Evidence indicates that dopamine system dysfunction is involved in negative symptoms of schizophrenia (SZ), including avolition and anhedonia. As such, we predicted that brain responses to TDEs in(More)
BACKGROUND Crack cocaine dependence and addiction is typically associated with frequent and intense drug wanting or craving triggered by internal or environmental cues associated with past drug use. METHODS Water O 15 positron emission tomography (PET) studies were used to localize alterations in synaptic activity related to cue-induced drug craving in 8(More)
Axotomy of sciatic nerve fibers in adult rats induces expression of NGF receptor in the entire population of Schwann cells located distal to the injury (Taniuchi et al., 1986b). In the present study we have used immunocytochemistry, with a monoclonal antibody directed against the rat NGF receptor, to examine axotomized peripheral nerves by light and(More)
Heightened distractibility in participants with ADHD as indexed by increased reaction time (RT) variability has been hypothesized to be due to a failure to sufficiently suppress activation in the default attention network during cognitively demanding situations. The present study utilized fMRI to examine the relationship between intra-individual variability(More)
Clinical and functional studies have strongly suggested that acetylcholine input from the nucleus basalis of Meynert is important for the cortex's adaptive response to experience. The purpose of this study was to investigate the effects of depletion of acetylcholine inputs from nucleus basalis of Meynert on experience-dependent plasticity in the cortex of(More)
In recent years, there has been growing enthusiasm that functional magnetic resonance imaging (MRI) could achieve clinical utility for a broad range of neuropsychiatric disorders. However, several barriers remain. For example, the acquisition of large-scale datasets capable of clarifying the marked heterogeneity that exists in psychiatric illnesses will(More)
This article reviews evidence for the presence of a compensatory, alternative, neural system and its possible link to associated processing strategies in children and adults with attention deficit hyperactivity disorder (ADHD). The article presents findings on a region by region basis that suggests ADHD should be characterized not only by neural(More)
BACKGROUND We examined the effect of prolonged methylphenidate (MPH) treatment on the functional neuroanatomy of executive functioning in adult men with attention-deficit/hyperactivity disorder (ADHD). METHODS Positron emission tomography with [(15)O] water measured alterations of regional cerebral blood flow (rCBF) during the Paced Auditory Serial(More)
Psychosis has been associated with aberrant brain activity concurrent with both the anticipation and integration of monetary outcomes. The extent to which abnormal reward-related neural signals can be observed in chronic, medicated patients with schizophrenia (SZ), however, is not clear. In an fMRI study involving 17 chronic outpatients with SZ and 17(More)