Functional neural networks underlying response inhibition in adolescents and adults

Age-related cognitive gains are mediated by the effects of white matter development on brain network integration

A fundamental, yet rarely tested premise of developmental cognitive neuroscience is that changes in brain activity and improvements in behavioral control across adolescent development are related to brain maturational factors that shape a more efficient, highly-interconnected brain in adulthood. We present the first multimodal neuroimaging study to empirically demonstrate that maturation of executive cognitive ability is directly associated with the relationship of white matter development and age-related changes in neural network functional integration. In this study, we identified specific white matter regions whose maturation across adolescence appears to reduce reliance on local processing in brain regions recruited for conscious, deliberate cognitive control in favor of a more widely distributed profile of functionally-integrated brain activity. Greater white matter coherence with age was associated with both increases and decreases in functional connectivity within task-engaged functional circuits. Importantly, these associations between white matter development and brain system functional integration were related to behavioral performance on tests of response inhibition, demonstrating their importance in the maturation of optimal cognitive control.

Functional connectivity during a social emotion task in adolescents and in adults

In this fMRI study we investigated functional connectivity between components of the mentalising system during a social emotion task, using psychophysiological interaction (PPI) analysis. Ten adults (22–32 years) and 18 adolescents (11–18 years) were scanned while thinking about scenarios in which a social or a basic emotion would be experienced. Unlike basic emotions (such as disgust and fear), social emotions (such as embarrassment and guilt) require the representation of another’s mental states. In both adults and adolescents, an anterior rostral region of medial prefrontal cortex (arMPFC) involved in mentalising showed greater connectivity with the posterior superior temporal sulcus (pSTS) bordering on the temporo-parietal junction (TPJ) and with anterior temporal cortex (ATC) during social than during basic emotion. This result provides novel evidence that components of the mentalising system interact functionally during a social emotion task. Furthermore, functional connectivity differed between adolescence and adulthood. The adolescent group showed stronger connectivity between arMPFC and pSTS/TPJ during social relative to basic emotion than did the adult group, suggestive of developmental changes in functional integration within the mentalising system.

Brain network dynamics during error commission

Previous studies suggest that the anterior cingulate and other prefrontal brain regions might form a functionally-integrated error detection network in the human brain. This study examined whole brain functional connectivity to both correct and incorrect button presses using independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) data collected from 25 adolescent and 25 adult healthy participants (ages 11-37) performing a visual Go/No-Go task. Correct responses engaged a network comprising left lateral prefrontal cortex, left postcentral gyrus/inferior parietal lobule, striatum, and left cerebellum. In contrast, a similar network was uniquely engaged during errors, but this network was not integrated with activity in regions believed to be engaged for higher-order cognitive control over behavior. A medial/dorsolateral prefrontal-parietal neural network responded to all No-Go stimuli, but with significantly greater activity to errors. ICA analyses also identified a third error-related circuit comprised of anterior temporal lobe, limbic, and pregenual cingulate cortices, possibly representing an affective response to errors. There were developmental differences in error-processing activity within many of these neural circuits, typically reflecting greater hemodynamic activation in adults. These findings characterize the spatial structure of neural networks underlying error commission and identify neurobiological differences between adolescents and adults.

Mining EEG-fMRI using independent component analysis

Independent component analysis (ICA) is a multivariate approach that has become increasingly popular for analyzing brain imaging data. In contrast to the widely used general linear model (GLM) that requires the user to parameterize the brain's response to stimuli, ICA allows the researcher to explore the factors that constitute the data and alleviates the need for explicit spatial and temporal priors about the responses. In this paper, we introduce ICA for hemodynamic (fMRI) and electrophysiological (EEG) data processing, and one of the possible extensions to the population level that is available for both data types. We then selectively review some work employing ICA for the decomposition of EEG and fMRI data to facilitate the integration of the two modalities to provide an overview of what is available and for which purposes ICA has been used. An optimized method for symmetric EEG-fMRI decomposition is proposed and the outstanding challenges in multimodal integration are discussed.

Functional connectivity of the inferior frontal cortex changes with age in children with autism spectrum disorders: a fcMRI study of response inhibition

Unmasking the neural basis of neurodevelopmental disorders, such as autism spectrum disorders (ASD), requires studying functional connectivity during childhood when cognitive skills develop. A functional connectivity magnetic resonance imaging (fcMRI) analysis was performed on data collected during Go/NoGo task performance from 24 children ages 8-12 years (12 with ASD; 12 controls matched on age and intellectual functioning). We investigated the connectivity of the left and right inferior frontal cortex (IFC; BA 47), key regions for response inhibition, with other active regions in frontal, striatal, and parietal cortex. Groups did not differ on behavioral measures or functional connectivity of either IFC region. A trend for reduced connectivity in the right IFC for the ASD group was revealed when controlling for age. In the ASD group, there was a significant negative correlation between age and 2 right IFC correlation pairs: right IFC-bilateral presupplementary motor area (BA 6) and right IFC-right caudate. Compared with typical controls, children with ASD may not have gross differences in IFC functional connectivity during response inhibition, which contrasts with an adult study of ASD that reported reduced functional connectivity. This discrepancy suggests an atypical developmental trajectory in ASD for right IFC connectivity with other neural regions supporting response inhibition.

Neurodevelopment and executive function in autism

Autism is a neurodevelopmental disorder characterized by social and communication deficits, and repetitive behavior. Studies investigating the integrity of brain systems in autism suggest a wide range of gray and white matter abnormalities that are present early in life and change with development. These abnormalities predominantly affect association areas and undermine functional integration. Executive function, which has a protracted development into adolescence and reflects the integration of complex widely distributed brain function, is also affected in autism. Evidence from studies probing response inhibition and working memory indicate impairments in these core components of executive function, as well as compensatory mechanisms that permit normative function in autism. Studies also demonstrate age-related improvements in executive function from childhood to adolescence in autism, indicating the presence of plasticity and suggesting a prolonged window for effective treatment. Despite developmental gains, mature executive functioning is limited in autism, reflecting abnormalities in wide-spread brain networks that may lead to impaired processing of complex information across all domains.

Dysfunction of the attentional brain network in children with Developmental Coordination Disorder: a fMRI study

Children with Developmental Coordination Disorder (DCD) present impaired motor skills, frequently associated with impaired attentional and executive functions. The objective of this study was to assess the impact of DCD on effective connectivity applied to a putative model of inhibition. fMRI was performed in 9 children with DCD and 10 control children (8-13 years old) performing a go-nogo task. As previously reported, children with DCD obtained a similar score for correct inhibitions as controls, but responses were slower and more variable than in controls. Compared to controls, Structural Equation Modeling indicated that: (1) path coefficients from both middle frontal cortex (MFC) and anterior cingulate cortex (ACC) to inferior parietal cortex (IPC) increased in children with DCD particularly in the left hemisphere; (2) path coefficients between striatum and parietal cortex decreased in children with DCD in the right hemisphere. Results suggest that DCD could be characterized by abnormal brain hemispheric specialization during development. Furthermore, connectivity in the MFC-ACC-IPC network could indicate that children with DCD are less able than healthy children to easily and/or promptly switch between go and nogo motor responses. However, children with DCD seem to compensate for this poor efficiency by more actively engaging the ACC to prevent commissions allowing maintenance of a good level of inhibition.

Developmental changes in neural activation and psychophysiological interaction patterns of brain regions associated with interference control and time perception

Interference control and time perception are mediated by common neural networks, including the frontal and parietal lobes, the cerebellum and the basal ganglia. Previous studies have shown that while time perception develops early in life, interference control seems to follow a protracted course of maturation into late adolescence. Thus, the current study examined developmental changes in neural activation and functional interaction between brain regions during a combined time discrimination and interference control task using fMRI. Thirty-four participants, aged 8-15 years, were scanned while performing a spatial stimulus response compatibility (SRC) task and a time discrimination (TD) task using identical stimuli. We found shared neural activation in a fronto-parieto-cerebellar network as well as task-specific patterns of psychophysiological interaction with positive coupling between the right inferior frontal gyrus (IFG), the superior parietal lobes bilaterally, the contralateral IFG and the thalamus during interference control and positive interactions between the right IFG and bilateral cerebellar activity and the thalamus during time discrimination. Developmental changes in task performance and brain activation patterns were only observed during the SRC task, with increased neural activity in the left inferior parietal gyrus and positive coupling between fronto-parietal brain regions that was only observed in the adolescents group. These results suggest that although both cognitive tasks rely on a shared neural network, distinct developmental curves of brain activation and connectivity could be observed associated with differential maturation patterns underlying cognitive development.

Impact of modeling on adolescent suicidal behavior

The evidence to date suggests that suicide modeling is a real phenomenon, although of a smaller effect size than other psychiatric and psychosocial risk factors for adolescent suicide. Multiple lines of inquiry provide converging evidence, including studies on suicide clusters, media influence on suicide (particularly coverage of nonfictional suicides), and peer influence on suicidality. Despite variations in study setting and methodology, the body of literature is consistent with a modeling hypothesis. Although advances in documentation of suicide modeling have been made over the past decade, we are still confronted by unresolved issues regarding the underlying mechanisms. Prevention and postvention strategies can be optimized to avert modeling of suicidal behavior only once research addresses the complexities and uncertainties of this phenomenon.