Progressive increase of frontostriatal brain activation from childhood to adulthood during event-related tasks of cognitive control

Increased cerebral perfusion in adult attention deficit hyperactivity disorder is normalised by stimulant treatment: a non-invasive MRI pilot study

The neurobiological basis for attention deficit hyperactivity disorder (ADHD) has not yet been fully established, although there is a growing body of evidence pointing to functional and structural abnormalities involving the basal ganglia, cerebellum, and regions of frontal grey matter. The purpose of this study was to investigate regional cerebral perfusion in adults with ADHD and age-matched control subjects, and to assess the perfusion response to stimulant treatment in the ADHD group using a non-invasive magnetic resonance perfusion imaging technique. Whole-brain cerebral perfusion images were acquired from nine right-handed male patients with ADHD and eleven age-matched control subjects using a continuous arterial spin labelling (CASL) technique. The ADHD group was assessed once on their normal treatment and once after withdrawing from treatment for at least one week. An automated voxel-based analysis was used to identify regions where the cerebral perfusion differed significantly between the ADHD and control groups, and where the perfusion altered significantly with stimulant treatment. Regional cerebral perfusion was increased in the ADHD group in the left caudate nucleus, frontal and parietal regions. Psychomotor stimulant treatment acted to normalise perfusion in frontal cortex and the caudate nucleus with additional decreases in parietal and parahippocampal regions. These findings highlight the potential sensitivity of non-invasive perfusion MRI techniques like CASL in the evaluation of perfusion differences due to illness and medication treatment, and provide further evidence that persistence of ADHD symptomatology into adulthood is accompanied by abnormalities in frontal and striatal brain regions.

Functional connectivity of human striatum: a resting state FMRI study

Classically regarded as motor structures, the basal ganglia subserve a wide range of functions, including motor, cognitive, motivational, and emotional processes. Consistent with this broad-reaching involvement in brain function, basal ganglia dysfunction has been implicated in numerous neurological and psychiatric disorders. Despite recent advances in human neuroimaging, models of basal ganglia circuitry continue to rely primarily upon inference from animal studies. Here, we provide a comprehensive functional connectivity analysis of basal ganglia circuitry in humans through a functional magnetic resonance imaging examination during rest. Voxelwise regression analyses substantiated the hypothesized motor, cognitive, and affective divisions among striatal subregions, and provided in vivo evidence of a functional organization consistent with parallel and integrative loop models described in animals. Our findings also revealed subtler distinctions within striatal subregions not previously appreciated by task-based imaging approaches. For instance, the inferior ventral striatum is functionally connected with medial portions of orbitofrontal cortex, whereas a more superior ventral striatal seed is associated with medial and lateral portions. The ability to map multiple distinct striatal circuits in a single study in humans, as opposed to relying on meta-analyses of multiple studies, is a principal strength of resting state functional magnetic resonance imaging. This approach holds promise for studying basal ganglia dysfunction in clinical disorders.

Brain volume reductions within multiple cognitive systems in male preterm children at age twelve

OBJECTIVES

To more precisely examine regional and subregional microstructural brain changes associated with preterm birth.

STUDY DESIGN

We obtained brain volumes from 29 preterm children, age 12 years, with no ultrasound scanning evidence of intraventricular hemorrhage or cystic periventricular leukomalacia in the newborn period, and 22 age- and sex-matched term control subjects.

RESULTS

Preterm male subjects demonstrated significantly lower white matter volumes in bilateral cingulum, corpus callosum, corticospinal tract, prefrontal cortex, superior and inferior longitudinal fasciculi compared with term male subjects. Gray matter volumes in prefrontal cortex, basal ganglia, and temporal lobe also were significantly reduced in preterm male subjects. Brain volumes of preterm female subjects were not significantly different from those of term female control subjects. Voxel-based morphometry results were not correlated with perinatal variables or cognitive outcome. Higher maternal education was associated with higher cognitive performance in preterm male subjects.

CONCLUSIONS

Preterm male children continue to demonstrate abnormal neurodevelopment at 12 years of age. However, brain morphology in preterm female children may no longer differ from that of term female children. The neurodevelopmental abnormalities we detected in preterm male subjects appear to be relatively diffuse, involving multiple neural systems. The relationship between aberrant neurodevelopment and perinatal variables may be mediated by genetic factors, environmental factors, or both reflected in maternal education level.

Executive dysfunction and delay aversion in attention deficit hyperactivity disorder: nosologic and diagnostic implications

In this article the authors reflect on the role of executive function (EF) deficits and delay aversion (DAv) in the diagnosis of attention deficit hyperactivity disorder (ADHD). The authors, empirical review shows clearly that EF deficits and DAv are implicated in ADHD, although neither is necessary for ADHD nor specific to it. The constructs are somewhat dissociable from one another so that each may represent a distinctive feature associated with an ADHD subsample. The authors argue that neither EF deficits nor DAv add much value to the diagnosis of ADHD as it is currently conceptualized, but may be crucial in helping to partition heterogeneity in the condition, leading to the refinement of ADHD nosology.

The teen brain: insights from neuroimaging

Few parents of a teenager are surprised to hear that the brain of a 16-year-old is different from the brain of an 8-year-old. Yet to pin down these differences in a rigorous scientific way has been elusive. Magnetic resonance imaging, with the capacity to provide exquisitely accurate quantifications of brain anatomy and physiology without the use of ionizing radiation, has launched a new era of adolescent neuroscience. Longitudinal studies of subjects from ages 3-30 years demonstrate a general pattern of childhood peaks of gray matter followed by adolescent declines, functional and structural increases in connectivity and integrative processing, and a changing balance between limbic/subcortical and frontal lobe functions, extending well into young adulthood. Although overinterpretation and premature application of neuroimaging findings for diagnostic purposes remains a risk, converging data from multiple imaging modalities is beginning to elucidate the implications of these brain changes on cognition, emotion, and behavior.

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. Anterior cingulate cortex (ACC) was a central focus. In rostral ACC all age groups showed significant deactivation during correct but not error trials, consistent with the proposal that such deactivation reflects suspension of a "default mode" necessary for effective controlled performance. In contrast, dorsal ACC showed increased and extended modulation for error versus correct trials in adults, which, in children and adolescents, was significantly attenuated. Further, younger age groups showed reduced activity in posterior attentional regions, relying instead on increased recruitment of regions within prefrontal cortex. This work suggests that functional changes in dorsal ACC associated with error regulation and error-feedback utilization, coupled with changes in the recruitment of "long-range" attentional networks, underlie age-related improvements in performance.

Relationship between chronic pain and cognition in cognitively intact older persons and in patients with Alzheimer's disease. The need to control for mood

BACKGROUND

Brain areas that are involved in cognition and mood also play a role in pain processing.

OBJECTIVE

The goal of the present study was to examine the relationship between chronic pain and cognition [executive functions (EF) and memory], while controlling for mood, in cognitively intact older persons and in patients with Alzheimer's disease (AD).

METHODS

Two groups of subjects participated: 20 older persons without dementia and 19 patients in an early stage of probable AD who suffered from arthrosis/arthritis. Pain intensity and pain affect were assessed by the Colored Analogue Scale for Pain Intensity and for Pain Affect, the Faces Pain Scale (FPS) and the Number of Words Chosen-Affective (NWC-A). Level of depression and anxiety were evaluated by questionnaires. EF and memory were assessed by neuropsychological tests.

RESULTS

The results show that significant correlations between specific cognitive functions, pain intensity and pain affect were lacking in the cognitively intact older persons. Cognition, in particular memory, appeared to be related to depressive symptoms. In contrast, a significant positive correlation was observed between EF, pain intensity and pain affect measured by the FPS in the AD group.

CONCLUSIONS

Although older persons with depression were excluded, in studies on pain and cognition one should control for the presence of depressive symptoms in older persons with and without dementia.

Brain activation in paediatric obsessive compulsive disorder during tasks of inhibitory control

BACKGROUND

Obsessive-compulsive disorder (OCD) may be related to a dysfunction in frontostriatal pathways mediating inhibitory control. However, no functional magnetic resonance imaging (fMRI) study has tested this in children.

AIMS

To test whether adolescents with OCD in partial remission would show abnormal frontostriatal brain activation during tasks of inhibition.

METHOD

Event-related fMRI was used to compare brain activation in 10 adolescent boys with OCD with that of 9 matched controls during three different tasks of inhibitory control.

RESULTS

During a 'stop' task, participants with OCD showed reduced activation in right orbitofrontal cortex, thalamus and basal ganglia; inhibition failure elicited mesial frontal underactivation. Task switching and interference inhibition were associated with attenuated activation in frontal, temporoparietal and cerebellar regions.

CONCLUSIONS

These preliminary findings support the hypothesis that paediatric OCD is characterised by a dysregulation of frontostriatothalamic brain regions necessary for motor inhibition, and also demonstrate dysfunction of temporoparietal and frontocerebellar attention networks during more cognitive forms of inhibition.

Neural correlates of reward in autism

BACKGROUND

Lack of social interaction, which is characteristically seen in people with autistic-spectrum disorder, may be caused by malfunctioning of the frontostriatal reward systems. However, no reported in vivo brain imaging studies have investigated reward mechanisms in autistic-spectrum disorder.

AIMS

To investigate functional brain activation during reward feedback in people with autistic-spectrum disorder and control individuals.

METHOD

We used event-related functional magnetic resonance imaging to examine the neural substrates of monetary reward in individuals with autistic-spectrum disorder and matched controls.

RESULTS

When rewarded, individuals with autism compared with control individuals showed significantly greater brain activation in the left anterior cingulate gyrus. In addition, activation of this region was negatively correlated with social interaction as measured by the Autism Diagnostic Interview.

CONCLUSIONS

In people with autistic-spectrum disorder, achieving reward is associated with significant differences in the activation of areas known to be responsible for attention and arousal, and this may partially underpin some deficits in social behaviour.

Inhibition of Action, Thought, and Emotion: A Selective Neurobiological Review

The neural bases of inhibitory function are reviewed, covering data from paradigms assessing inhibition of motor responses (antisaccade, go/nogo, stop-signal), cognitive sets (e.g., Wisconsin Card Sort Test), and emotion (fear extinction). The frontal cortex supports performance on these paradigms, but the specific neural circuitry varies: response inhibition depends upon fronto-basal ganglia networks, inhibition of cognitive sets is supported by orbitofrontal cortex, and retention of fear extinction reflects ventromedial prefrontal cortexamygdala interactions. Inhibition is thus neurobiologically heterogeneous, although right ventrolateral prefrontal cortex may support a general inhibitory process. Dysfunctions in these circuits may contribute to psychopathological conditions marked by inhibitory deficits.

Temporal lobe dysfunction in medication-naïve boys with attention-deficit/hyperactivity disorder during attention allocation and its relation to response variability

BACKGROUND

Patients with attention-deficit/hyperactivity disorder (ADHD) typically show fronto-striatal abnormalities during functions of cognitive control. In this study we investigate whether medication-naïve children with ADHD are impaired in temporo-parietal neural networks that mediate purely perceptual attention allocation to a behaviorally neutral oddball task. Furthermore, we explore the relationship between the neural substrates of attention allocation and response variability, typically increased in patients.

METHOD

Event-related functional magnetic resonance imaging was used to compare brain activation of 17 medication-naïve boys with ADHD with that of 18 handedness- and IQ-matched healthy comparison boys during a visual oddball task that required the same response to oddball and standard trials. Furthermore, to explore the relationship between behavioral dispersion and attention networks, regression analyses were conducted between response variability and brain activation networks.

RESULTS

Patients showed significantly reduced brain activation in left and right superior temporal lobes, basal ganglia, and posterior cingulate during the oddball versus standard contrast. The activation differences in superior temporal lobes correlated inversely with response variability in control subjects but not in patients with ADHD.

CONCLUSIONS

Brain abnormalities in patients with ADHD are not confined to fronto-striatal networks mediating executive functions but are also observed in temporo-striatal and cingulate regions during perceptive visual attention processes. Furthermore, temporal lobe dysfunction in the context of perceptual attention might be related to their behavioral problems with response variability.

Linear age-correlated functional development of right inferior fronto-striato-cerebellar networks during response inhibition and anterior cingulate during error-related processes

Inhibitory and performance-monitoring functions have been shown to develop throughout adolescence. The developmental functional magnetic resonance imaging (fMRI) literature on inhibitory control, however, has been relatively inconsistent with respect to functional development of prefrontal cortex in the progression from childhood to adulthood. Age-related performance differences between adults and children have been shown to be a confound and may explain inconsistencies in findings. The development of error-related processes has not been studied so far using fMRI. The aim of this study was to investigate the neural substrates of the development of inhibitory control and error-related functions by use of an individually adjusted task design that forced subjects to fail on 50% of trials, and therefore controlled for differences in task difficulty and performance between different age groups. Event-related fMRI was used to compare brain activation between 21 adults and 26 children/adolescents during successful motor inhibition and inhibition failure. Adults compared with children/adolescents showed increased brain activation in right inferior prefrontal cortex during successful inhibition and in anterior cingulate during inhibition failure. A whole-brain age-regression analysis between 10 and 42 years showed progressive age-related changes in activation in these two brain regions, with additional changes in thalamus, striatum, and cerebellum. Age-correlated brain regions correlated with each other and with inhibitory performance, suggesting they form developing fronto-striato-thalamic and fronto-cerebellar neural pathways for inhibitory control. This study shows developmental specialization of the integrated function of right inferior prefrontal cortex, basal ganglia, thalamus, and cerebellum for inhibitory control and of anterior cingulate gyrus for error-related processes.

Physiology and pathology of eye–head coordination

Human head movement control can be considered as part of the oculomotor system since the control of gaze involves coordination of the eyes and head. Humans show a remarkable degree of flexibility in eye-head coordination strategies, nonetheless an individual will often demonstrate stereotypical patterns of eye-head behaviour for a given visual task. This review examines eye-head coordination in laboratory-based visual tasks, such as saccadic gaze shifts and combined eye-head pursuit, and in common tasks in daily life, such as reading. The effect of the aging process on eye-head coordination is then reviewed from infancy through to senescence. Consideration is also given to how pathology can affect eye-head coordination from the lowest through to the highest levels of oculomotor control, comparing conditions as diverse as eye movement restrictions and schizophrenia. Given the adaptability of the eye-head system we postulate that this flexible system is under the control of the frontal cortical regions, which assist in planning, coordinating and executing behaviour. We provide evidence for this based on changes in eye-head coordination dependant on the context and expectation of presented visual stimuli, as well as from changes in eye-head coordination caused by frontal lobe dysfunction.

Neurobiological underpinnings of insight deficits in schizophrenia

Impaired insight into illness is commonly observed across various psychiatric illnesses, but is most frequent in patients with schizophrenia. The clinical relevance and public health impact of poor insight is reflected by its close association with important clinical outcome measures, such as treatment non-adherence, lower psychosocial functioning, poor prognosis, involuntary hospitalization, and higher utilization of emergency services. Although the neurobiology of insight has not been determined, data from neurocognitive and a few structural imaging studies provide some understanding of the neurobiological underpinnings of insight function in schizophrenia. Using published and preliminary data, we propose a hypothetical model of insight that may help initiate neurobiological investigations in this complex area.

Executive control over response priming and conflict: a transcranial magnetic stimulation study

In the present study repetitive transcranial magnetic stimulation (rTMS) was utilised to interrupt neural activity in selected cortical areas at several different time periods while participants performed a stimulus-response correspondence (SRC) task. Responses are usually faster and less error-prone when stimulus (S) and response (R) features correspond than when they do not. Dual-route models of response preparation account for such SRC effects by postulating an indirect route performing S-R selection and a parallel direct route where S features prime their corresponding responses. SRC effects have recently been shown to depend on the preceding trial type, that is, SRC effects are largely reduced when preceded by a non-corresponding trial as compared to a preceding corresponding trial. Present results show that this context dependency of the SRC effect was hindered when rTMS was applied to the left dorsolateral prefrontal cortex (DLPFC) 500-300 ms before the onset of the next trial. Moreover, the SRC effect was reduced overall when applying rTMS volleys to the right posterior parietal cortex (PPC) for 200 ms with the onset of the visual stimulus. We conclude that the left DLPFC is involved in the context-dependent control of response conflicts, whereas the right PPC serves early visuomotor transformations and is, therefore, related to direct route priming.

Functional neural networks underlying response inhibition in adolescents and adults

This study provides the first description of neural network dynamics associated with response inhibition in healthy adolescents and adults. Functional and effective connectivity analyses of whole brain hemodynamic activity elicited during performance of a Go/No-Go task were used to identify functionally integrated neural networks and characterize their causal interactions. Three response inhibition circuits formed a hierarchical, inter-dependent system wherein thalamic modulation of input to premotor cortex by fronto-striatal regions led to response suppression. Adolescents differed from adults in the degree of network engagement, regional fronto-striatal-thalamic connectivity, and network dynamics. We identify and characterize several age-related differences in the function of neural circuits that are associated with behavioral performance changes across adolescent development.

Impaired executive functioning in young adults born very preterm

Individuals born very preterm (VPT) are at increased risk of perinatal brain injury and long-term cognitive and behavioral problems. Executive functioning, in particular, has been shown to be impaired in VPT children and adolescents. This study prospectively assessed executive function in young adults who were born VPT (<33 weeks of gestation) [n = 61; mean age, 22.25 (+/-1.07) years; range, 20.62-24.78 years] and controls [n = 64; mean age, 23.20 (+/-1.48) years; range, 19.97-25.46 years]. Tests used comprised the Wechsler Abbreviated Scale of Intelligence (WASI), the Hayling Sentence Completion Test (HSCT), the Controlled Oral Word Association Test (COWAT), the Animal and Object test, the Trail-Making Test (TMT), and the Test of Attentional Performance (TAP). VPT participants showed specific executive function impairments in tasks involving response inhibition and mental flexibility, even when adjusting for IQ, gender, and age. No significant associations were observed between executive function test scores and perinatal variables or neonatal ultrasound classification. The results suggest that, although free from major physical disability, VPT young adults perform worse than controls on tasks involving selective aspects of executive processing, such as mental flexibility and response inhibition.

Controlling emotional expression: behavioral and neural correlates of nonimitative emotional responses

Emotional facial expressions can engender similar expressions in others. However, adaptive social and motivational behavior can require individuals to suppress, conceal, or override prepotent imitative responses. We predicted, in line with a theory of "emotion contagion," that when viewing a facial expression, expressing a different emotion would manifest as behavioral conflict and interference. We employed facial electromyography (EMG) and functional magnetic resonance imaging (fMRI) to investigate brain activity related to this emotion expression interference (EEI) effect, where the expressed response was either concordant or discordant with the observed emotion. The Simon task was included as a nonemotional comparison for the fMRI study. Facilitation and interference effects were observed in the latency of facial EMG responses. Neuroimaging revealed activation of distributed brain regions including anterior right inferior frontal gyrus (brain area [BA] 47), supplementary motor area (facial area), posterior superior temporal sulcus (STS), and right anterior insula during emotion expression-associated interference. In contrast, nonemotional response conflict (Simon task) engaged a distinct frontostriatal network. Individual differences in empathy and emotion regulatory tendency predicted the magnitude of EEI-evoked regional activity with BA 47 and STS. Our findings point to these regions as providing a putative neural substrate underpinning a crucial adaptive aspect of social/emotional behavior.

On the programming and reprogramming of actions

Actions are often selected in the context of ongoing movement plans. Most studies of action selection have overlooked this fact, implicitly assuming that the motor system is passive prior to presentation of instructions triggering movement selection. Other studies addressed action planning in the context of an already present motor plan, but focused mostly on inhibition of a prepotent response under fierce time pressure. Under these circumstances, inhibition of previous motor plans and selection of a new response become temporally intermingled. Here, we explore how the presence of earlier motor plans influences cerebral effects associated with action selection, separating in time movement programming, reprogramming, and execution. We show that portions of parietofrontal circuits, including intraparietal sulcus and left dorsal premotor cortex, are systematically involved in programming motor responses, their activity being indifferent to the presence of earlier motor plans. We identify additional regions recruited when a motor response is programmed in the context of an existing motor program. We found that several right-hemisphere regions, previously associated with response inhibition, might be better characterized as involved in response selection. Finally, we detail the specific role of a right precentral region in movement reprogramming that is involved in inhibiting not only actual responses but also motor representations.

Neurodevelopmental changes in working memory and cognitive control

One of the most salient ways in which our behavior changes during childhood and adolescence is that we get better at working towards long-term goals, at ignoring irrelevant information that could distract us from our goals, and at controlling our impulses - in other words, we exhibit improvements in cognitive control. Several recent magnetic resonance imaging studies have examined the developmental changes in brain structure and function that underlie improvements in working memory and cognitive control. Increased recruitment of task-relevant regions in the prefrontal cortex, parietal cortex and striatum over the course of development is associated with better performance in a range of cognitive tasks. Further work is needed to assess the role of experience in shaping the neural circuitry that underlies cognitive control.