ADHD and cannabis use in young adults examined using fMRI of a Go/NoGo task.

Children diagnosed with attention-deficit/hyperactivity disorder (ADHD) are at increased risk for substance abuse. Response inhibition is a hallmark of ADHD, yet the combined effects of ADHD and regular substance use on neural networks associated with response inhibition are unknown. Task-based functional Magnetic Resonance Imaging (fMRI) data from young adults with childhood ADHD with (n = 25) and without (n = 25) cannabis use ≥ monthly in the past year were compared with a local normative comparison group (LNCG) with (n = 11) and without (n = 12) cannabis use.

Abnormalities in brain systems supporting individuation and enumeration in autism.

Previous work indicates that adults with autism display a decreased capacity when rapidly enumerating small sets of elements (i.e., subitizing), compared to typically developing (TD) individuals.

The strength of gradually accruing probabilistic evidence modulates brain activity during a categorical decision.

The evolution of neural activity during a perceptual decision is well characterized by the evidence parameter in sequential sampling models. However, it is not known whether accumulating signals in human neuroimaging are related to the integration of evidence. Our aim was to determine whether activity accumulates in a nonperceptual task by identifying brain regions tracking the strength of probabilistic evidence.

Investigating inhibitory control in children with epilepsy: an fMRI study.

Objective: Deficits in executive function are noted increasingly in children with epilepsy and have been associated with poor academic and psychosocial outcomes. Impaired inhibitory control contributes to executive dysfunction in children with epilepsy; however, its neuroanatomic basis has not yet been investigated. We used functional magnetic resonance imaging (fMRI) to probe the integrity of activation in brain regions underlying inhibitory control in children with epilepsy.

Longitudinal growth curves of brain function underlying inhibitory control through adolescence.

Neuroimaging studies suggest that developmental improvements in inhibitory control are primarily supported by changes in prefrontal executive function. However, studies are contradictory with respect to how activation in prefrontal regions changes with age, and they have yet to analyze longitudinal data using growth curve modeling, which allows characterization of dynamic processes of developmental change, individual differences in growth trajectories, and variables that predict any interindividual variability in trajectories. In this study, we present growth curves modeled from longitudinal fMRI data collected over 302 visits (across ages 9 to 26 years) from 123 human participants.

Impact of ADHD and cannabis use on executive functioning in young adults.

Background: Attention-deficit/hyperactivity disorder (ADHD) and cannabis use are each associated with specific cognitive deficits. Few studies have investigated the neurocognitive profile of individuals with both an ADHD history and regular cannabis use. The greatest cognitive impairment is expected among ADHD Cannabis Users compared to those with ADHD-only, Cannabis use-only, or neither.

Distinct neural signatures detected for ADHD subtypes after controlling for micro-movements in resting state functional connectivity MRI data.

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 need to be realized.

Strengthening of top-down frontal cognitive control networks underlying the development of inhibitory control: a functional magnetic resonance imaging effective connectivity study.

The ability to voluntarily inhibit responses to task-irrelevant stimuli, which is a fundamental component of cognitive control, has a protracted development through adolescence. Previous human developmental imaging studies have found immaturities in localized brain activity in children and adolescents. However, little is known about how these regions integrate with age to form the distributed networks known to support cognitive control.

A parcellation scheme for human left lateral parietal cortex.

The parietal lobe has long been viewed as a collection of architectonic and functional subdivisions. Though much parietal research has focused on mechanisms of visuospatial attention and control-related processes, more recent functional neuroimaging studies of memory retrieval have reported greater activity in left lateral parietal cortex (LLPC) when items are correctly identified as previously studied ("old") versus unstudied ("new"). These studies have suggested functional divisions within LLPC that may provide distinct contributions toward recognition memory judgments.

Methodological approaches in developmental neuroimaging studies.

Pediatric neuroimaging is increasingly providing insights into the neural basis of cognitive development. Indeed, we have now arrived at a stage where we can begin to identify optimal methodological and statistical approaches to the acquisition and analysis of developmental imaging data. In this article, we describe a number of these approaches and how their selection impacts the ability to examine and interpret developmental effects.

The maturation of task set-related activation supports late developmental improvements in inhibitory control.

The ability to voluntarily inhibit a single response is evident early in development, even as the ability to maintain an inhibitory "task set" continues to improve. To date, functional neuroimaging studies have detailed developmental changes in systems supporting inhibitory control exerted at the single-trial level, but changes underlying the ability to maintain an inhibitory task set remain little understood. Here we present findings from a functional magnetic resonance imaging study that characterizes the development of systems supporting both transient (trial-related) and sustained (task set-related) activation during performance of the antisaccade task-an oculomotor test of inhibitory control (Hallett, 1978).

Left posterior parietal cortex participates in both task preparation and episodic retrieval.

Optimal memory retrieval depends not only on the fidelity of stored information, but also on the attentional state of the subject. Factors such as mental preparedness to engage in stimulus processing can facilitate or hinder memory retrieval. The current study used functional magnetic resonance imaging (fMRI) to distinguish preparatory brain activity before episodic and semantic retrieval tasks from activity associated with retrieval itself.

Development of eye-movement control.

Cognitive control of behavior continues to improve through adolescence in parallel with important brain maturational processes including synaptic pruning and myelination, which allow for efficient neuronal computations and the functional integration of widely distributed circuitries supporting top-down control of behavior. This is also a time when psychiatric disorders, such as schizophrenia and mood disorders, emerge reflecting a particularly vulnerability to impairments in development during adolescence. Oculomotor studies provide a unique neuroscientific approach to make precise associations between cognitive control and brain circuitry during development that can inform us of impaired systems in psychopathology.

Dissociating early and late error signals in perceptual recognition.

Decisions about object identity follow a period in which evidence is gathered and analyzed. Evidence can consist of both task-relevant external stimuli and internally generated goals and expectations. How the various pieces of information are gathered and filtered into meaningful evidence by the nervous system is largely unknown.

Maturational changes in anterior cingulate and frontoparietal recruitment support the development of error processing and inhibitory control.

Documenting the development of the functional anatomy underlying error processing is critically important for understanding age-related improvements in cognitive performance. Here we used functional magnetic resonance imaging to examine time courses of brain activity in 77 individuals aged 8-27 years during correct and incorrect performance of an oculomotor task requiring inhibitory control. Canonical eye-movement regions showed increased activity for correct versus error trials but no differences between children, adolescents and young adults, suggesting that core task processes are in place early in development.

Evidence accumulation and the moment of recognition: dissociating perceptual recognition processes using fMRI.

Decision making can be conceptualized as the culmination of an integrative process in which evidence supporting different response options accumulates gradually over time. We used functional magnetic resonance imaging to investigate brain activity leading up to and during decisions about perceptual object identity. Pictures were revealed gradually and subjects signaled the time of recognition (T(R)) with a button press.

Evidence for frontally mediated controlled processing differences in older adults.

Advanced aging is associated with slower and less flexible performance on demanding cognitive tasks. Here we used rapid event-related functional magnetic resonance imaging to explore differences between young (n = 65) and older adults (n = 75) during memory retrieval. Methods were optimized to afford exploration of both amplitude and timing differences in neural activity.

Evidence for separate perceptual reactivation and search processes during remembering.

Remembering involves the coordinated recruitment of strategic search processes and processes involved in reconstructing the content of the past experience. In the present study we used a cueing paradigm based on event-related functional magnetic resonance imaging to separate activity in the initial preparation phases of retrieval from later phases during which retrieval search ensued, and detailed auditory and visual memories were reconstructed. Results suggest a dissociation among inferior temporal (IT) and parieto-occipital (PO) processing regions in how they were influenced by preparatory cues prior to remembering, and indicate a dissociation in how they were influenced by the subsequent validity of those cues during remembering.

Functional-anatomic correlates of sustained and transient processing components engaged during controlled retrieval.

Controlled processing is central to episodic memory retrieval. In the present study, neural correlates of sustained, as well as transient, processing components were explored during controlled retrieval using a mixed blocked event-related functional magnetic resonance imaging paradigm. Results from 29 participants suggest that certain regions in prefrontal cortex, including anterior left inferior prefrontal cortex near Brodmann's Area (BA) 45/47 and more posterior and dorsal left prefrontal cortex near BA 44, increase activity on a trial-by-trial basis when high levels of control are required during retrieval.