Samantha J. Broyd

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In this review we are concerned specifically with the putative role of the default-mode network (DMN) in the pathophysiology of mental disorders. First, we define the DMN concept with regard to its neuro-anatomy, its functional organisation through low frequency neuronal oscillations, its relation to other recently discovered low frequency resting state(More)
BACKGROUND Resting brain activity appears altered in Attention Deficit/Hyperactivity Disorder (ADHD). The default mode interference hypothesis (Sonuga-Barke and Castellanos, 2007) postulates that patterns of spontaneous very low frequency brain activity, typical of the resting brain, cause attention lapses in ADHD when they remain unattenuated following the(More)
Children with Attention Deficit/Hyperactivity Disorder (AD/HD) appear to be deficient in inhibitory processes, as reflected in behavioural and electrophysiological measures. This study examined the effect of methylphenidate (MPH) on response inhibition in children with AD/HD. Event-related potentials (ERPs) and skin conductance level (SCL) were recorded(More)
BACKGROUND The default-mode network (DMN) is characterised by coherent very low frequency (VLF) brain oscillations. The cognitive significance of this VLF profile remains unclear, partly because of the temporally constrained nature of the blood oxygen-level dependent (BOLD) signal. Previously we have identified a VLF EEG network of scalp locations that(More)
BACKGROUND The ability to anticipate and then secure future rewards and avoid future punishments by responding effectively to environmental demands is at the core of successful decision making. Disruptions to these processes have been shown to be implicated in a number of psychiatric conditions. In the current paper we use the electrophysiological monetary(More)
OBJECTIVE Patients with ADHD are typically more variable in their reaction times (RT) than control children. Signal processing analyses have shown that time series RT data of children with ADHD have a distinctive low frequency periodic structure suggestive of a pattern of occasional spontaneous performance lapses. Here we use a fine-grained analysis of(More)
BACKGROUND The ubiquitous tendency to choose immediate over delayed rewards can, in extremis, lead to maladaptive preferences for smaller sooner over larger later rewards (i.e., impulsive choice) in certain pathological groups. The delay aversion hypothesis provides one possible account of impulsive choice and argues that this tendency is motivated by the(More)
Chronic cannabis use has been associated with neurocognitive deficits, alterations in brain structure and function, and with psychosis. This study investigated the effects of chronic cannabis use on P50 sensory-gating in regular users, and explored the association between sensory gating, cannabis use history and the development of psychotic-like symptoms.(More)
The ability to regulate our emotional responses is crucial to effective functioning in daily life. Whilst there has been extensive study of the brain potentials related to valenced stimuli, the neural basis of the ability to regulate actions elicited by these remains to be clarified. To address this, 40 volunteers undertook an approach-avoidance paradigm.(More)
Previous research investigating the effects of stimulants, such as methylphenidate (MPH), on children with attention deficit/hyperactivity disorder (AD/HD) has rarely included autonomic measures of arousal. Our aim was to clarify the effects of MPH on central and autonomic measures in AD/HD children during a continuous performance task (CPT) using a(More)