Central Executive Network and Executive Function in Patients With Alzheimer's Disease and Healthy Individuals: Meta-Analysis of Structural and Functional MRI.

OBJECTIVE: The neural architecture of executive function is of interest given its utility as a transdiagnostic predictor of adaptive functioning. However, a gap exists in the meta-analytic literature assessing this relationship in neuropsychiatric populations, concordance between structural and functional architecture, and the relationship with neuropsychological assessment of executive function. Given the importance of the central executive network (CEN) in Alzheimer's disease, this population may be useful in understanding this relationship in Alzheimer's disease pathology. METHODS: A meta-analysis of studies (k=21) was conducted to elucidate the relationship between executive function and CEN for structural architecture (k=10; N=1,027) among patients with Alzheimer's disease (k=6; N=250) and healthy control subjects (HCs) (k=4; N=777) and for functional architecture (k=11; N=522) among patients with Alzheimer's disease (k=6; N=306) and HCs (k=5; N=216). Random-effects modeling was used to increase accuracy of conclusions about population means. RESULTS: Analyses revealed a positive brain-behavior relationship (pr=0.032, 95% CI=0.07, 0.54), although there was a lack of statistically significant heterogeneity between functional and structural neuroimaging (Q=9.89, p=0.971, I2=0.00%) and between the Alzheimer's and HC groups in functional (Q=8.18, p=0.612, I2=0.00%) and structural (Q=1.60, p=0.996, I2=0.00%) neuroimaging. Similarly, a lack of statistically significant heterogeneity was revealed between functional and structural neuroimaging among patients with Alzheimer's disease (Q=3.59, p=0.980, I2=0.00%) and HCs (Q=3.67, p=0.885, I2=0.00%). CONCLUSIONS: Structural and functional imaging in the CEN are predictive of executive function performance among patients with Alzheimer's disease and HCs. Regardless of how the CEN is affected, behavior is correlated to the degree to which the CEN is affected. Findings are significant in the context of methodological decisions in multimodal neuroimaging research.

Factors in the neurodevelopment of negative urgency: Findings from a community-dwelling sample.

This study investigated neuroanatomic, genetic, cognitive, sociodemographic and emotional underpinnings of the Negative Urgency subscale of the Urgency, Premeditation, Perseverance, Sensation-Seeking and Positive Urgency Impulsive Behavior Scale in a healthy developmental sample. The goal of the investigation is to contribute to the harmonisation of behavioural, brain and neurogenetic aspects of behavioural self-control. Three domains - (1) Demographic, developmental, psychiatric and cognitive ability; (2) Regional brain volumes (neurobiological); and (3) Genetic variability (single nucleotide polymorphisms) - were examined, and models with relevant predictor variables were selected. Least absolute shrinkage and selection operator and best subset regressions were used to identify sparse models predicting negative urgency scores, which revealed that variables related to emotional regulation and right cingulate volume, as well as single nucleotide polymorphisms in CADM2 and SLC6A4, were associated with negative urgency. Our results contribute to the construct and criterion validity of negative urgency and support the hypothesis that negative urgency is a result of a complex array of influences across domains whose integration furthers developmental psychopathology research.

The central executive network and executive function in healthy and persons with schizophrenia groups: a meta-analysis of structural and functional MRI.

This meta-analysis evaluated the extent to which executive function can be understood with structural and functional magnetic resonance imaging. Studies included structural in schizophrenia (k = 8; n = 241) and healthy controls (k = 12; n = 1660), and functional in schizophrenia (k = 4; n = 104) and healthy controls (k = 12; n = 712). Results revealed a positive association in the brain behavior relationship when pooled across schizophrenia and control samples for structural (pr = 0.27) and functional (pr = 0.29) modalities. Subgroup analyses revealed no significant difference for functional neuroimaging (pr = .43, 95%CI = -.08-.77, p = .088) but with structural neuroimaging (pr = .37, 95%CI = -.08-.69, p = .015) the association to executive functions is lower in the control group. Subgroup analyses also revealed no significant differences in the strength of the brain-behavior relationship in the schizophrenia group (pr = .59, 95%CI = .58-.61, p = .881) or the control group (pr = 0.19, 95%CI = 0.18-0.19, p = 0.920), suggesting concordance.

Age-dependent relationship of cardiorespiratory fitness and white matter integrity.

Growing evidence has linked cardiorespiratory fitness (CRF) to more conserved white matter (WM) microstructure. Additional research is needed to determine which WM tracts are most strongly related to CRF and if the neuroprotective effects of CRF are age-dependent. Participants were community-dwelling adults (N = 499; ages 20-85) from the open-access Nathan Kline Institute - Rockland Sample (NKI-RS) with CRF (bike test) and diffusion tensor imaging (DTI) data. Mixed-effect modeling tested the interaction between CRF and age on global (main effect across 9 tracts) and local (individual tract effects) WM microstructure. Among older participants (age ≥ 60), CRF was significantly related to whole-brain (z-score slope = 0.11) and local WM microstructure within several tracts (| z-score slope | range = 0.13 - 0.27). Significant interactions with age indicated that the CRF-WM relationship was weaker (z-score slope ≤ 0.11) and more limited (one WM tract) in younger adults. The findings highlight the importance of aerobic exercise to maintain brain health into senescence. CRF may preferentially preserve a collection of anterior and posterior WM connections related to visuomotor function.

White matter connectometry among individuals with self-reported family history of drug and alcohol use disorders.

Heredity is an important risk factor for alcoholism. Several studies have been conducted on small groups of alcohol naïve adolescents which show lowered fractional anisotropy of frontal white matter in individuals with a family history of alcohol and substance use disorder (FH+). We compare large adult FH+ and FH- groups using white matter connectometry, different from the previously used global tractography method, as it is more sensitive to regional variability. Imaging and behavioral data from the Human Connectome Project (WU-MINN HCP 1200) was analyzed. Groups of participants were positive (n = 109) and negative (n = 109) for self-reported alcohol and substance use disorders in at least one parent, and stringently matched. Connectometry was performed on diffusion MRI in DSI-Studio using q-space diffeomorphic reconstruction, and multiple regression was completed with 5000 permutations. Analyses showed decreased major tract (>40 mm) connectivity in the FH+ group in left inferior longitudinal fasciculus, bilateral cortico-striatal pathway, left cortico-thalamic pathway, and corpus callosum, compared to the FH- group. For cognitive tasks related to reward processing, inhibition, and monitoring, there were a number of interactions, such that the relationship between identified tracts and behavior differed significantly between groups. Self-reported family history was associated with decreased connectivity in reward signaling pathways, controlling for alcohol consumption and alcohol use disorder. This is the first connectometry study of FH+, and extends the neural basis of the hereditary diathesis of alcoholism beyond that demonstrated with global tractography. Regions associated with FH+ are similar to those associated with alcohol use disorder.

Components of executive function model regional prefrontal volumes.

OBJECTIVE: Designed to measure a diversity of executive functioning (EF) through classical neuropsychological tests, the Delis-Kaplan Executive Function Scale (D-KEFS) allows for the investigation of the neural architecture of EF. We examined how the D-KEFS Tower, Verbal Fluency, Design Fluency, Color-Word Interference, and Trail Making Test tasks related to frontal lobe volumes, quantifying the regional specificity of EF components. METHOD: Adults from the Nathan Kline Institute-Rockland Sample (NKI-RS), an open-access community study of brain development, with complete MRI (3T scanner) and D-KEFS data were selected for analysis (N = 478; ages 20-85). In a mixed-effects model predicting volume, D-KEFS task, D-KEFS score, region of interest (ROI; 13 frontal, 1 occipital control), were entered as fixed effects with intercepts for participants as random effects. RESULTS: "Unitary" EF (aggregate of D-KEFS scores) was positively associated with superior frontal, rostral middle frontal, and lateral orbitofrontal volumes; a negative association was observed with frontal pole volume (| z-score slope | range = 0.040 to 0.051). "Diverse" EF skills (individual D-KEFS task scores) were differentially associated with two or three ROIs, respectively, but to a stronger extent (| z-score slope | range = 0.053 to 0.103). CONCLUSIONS: The neural correlates found for the D-KEFS support the prefrontal modularity of both unitary (aspects of EF ability common to all tasks) and diverse EF. Our findings contribute to emerging evidence that aggregate measurements of EF may serve broader but less robust frontal neural correlates than distinct EF skills. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Identifying errors in Freesurfer automated skull stripping and the incremental utility of manual intervention.

Quality assurance (QA) is vital for ensuring the integrity of processed neuroimaging data for use in clinical neurosciences research. Manual QA (visual inspection) of processed brains for cortical surface reconstruction errors is resource-intensive, particularly with large datasets. Several semi-automated QA tools use quantitative detection of subjects for editing based on outlier brain regions. There were two project goals: (1) evaluate the assumption that statistical outliers are related to errors of cortical extension, and (2) examine whether error identification and correction significantly impacts estimation of cortical parameters and established brain-behavior relationships. T1 MPRAGE images (N = 530) of healthy adults were obtained from the NKI-Rockland Sample and reconstructed using Freesurfer 5.3. Visual inspection of T1 images was conducted for: (1) participants (n = 110) with outlier values (z scores ±3 SD) for subcortical and cortical segmentation volumes (outlier group), and (2) a random sample of remaining participants (n = 110) with segmentation values that did not meet the outlier criterion (non-outlier group). The outlier group had 21% more participants with visual inspection-identified errors than participants in the non-outlier group, with a medium effect size (Φ = 0.22). Nevertheless, a considerable portion of images with errors of cortical extension were found in the non-outlier group (41%). Although nine brain regions significantly changed size from pre- to post-editing (with effect sizes ranging from 0.26 to 0.59), editing did not substantially change the correlations of neurocognitive tasks and brain volumes (ps > 0.05). Statistically-based QA, although less resource intensive, is not accurate enough to supplant visual inspection. We discuss practical implications of our findings to guide resource allocation decisions for image processing.

On the impact of interhemispheric white matter: Age, executive functioning, and dedifferentiation in the frontal lobes.

INTRODUCTION: In middle age, declines in executive functioning (EF) are associated with decrements in the quality and/or quantity of white and grey matter. Recruitment of homologous regions has been identified as a compensatory mechanism for cognitive decline in later middle age; however, research into neural substrates of EF has yet to be guided by dedifferentiation models. We hypothesized that frontal-parietal grey matter volume, interhemispheric white matter, and intrahemispheric white matter fractional anisotropy will be predictive of EF. Further, we hypothesized that the comparative association between interhemispheric white matter and EF will increase with age, because of compensatory recruitment. METHODS: Neurocognitive test data, DTI, and T1 MPRAGE scans (n = 444) were obtained from the NKI-Rockland Sample. Structural equation modeling was used to examine the relationship between age, EF, interhemispheric white matter (forceps minor; FM), intrahemispheric white matter (superior longitudinal fasciculus; SLF), and a frontal-parietal grey matter network. EF and grey matter were modelled as latent variables, with EF examined as the criterion. Additionally, a subsample of participants aged 55 to 85 (n = 168) was analyzed to examine the influence of age related compensatory mechanisms. RESULTS: There was a significant relationship between FM, grey matter, and EF, which was fully mediated by age. There was a significant relationship between SLF and EF, which was not mediated by age. For older adults, only the age-mediated pathway from FM to EF was significant. DISCUSSION: Using structural imaging data, support was found for age-related interhemispheric mechanisms of compensation, but not intrahemispheric mechanisms.

The use of neuropsychological tests to assess intelligence.

OBJECTIVE: We sought to derive a 'neuropsychological intelligence quotient' (NIQ) to replace IQ testing in some routine assessments. METHOD: We administered neuropsychological testing and a seven-subtest short form of the Wechsler Adult Intelligence Scale to a community sample of 394 adults aged 18-96 years. We regressed Wechsler Full Scale IQs (W-FSIQ) on 23 neuropsychological scores and derived an NIQ from 9 measures that explained significant variance in W-FSIQ. We then compared subgroups of 284 healthy and 108 unhealthy participants in NIQ and W-FSIQ to assess criterion validity, correlated NIQ and W-FSIQ scores with education level and independence for activities of daily living to assess convergent validity, and compared validity coefficients for the NIQ with those of 'hold' and 'no-hold' indices. RESULTS: By design, NIQ and W-FSIQ scores correlated highly (r = .84), and both were higher in healthy participants. The difference was larger for NIQ, which accounted for more variability in activities of daily living. The NIQ and 'no-hold' index were better predicted by health status and less predicted by educational status than the 'hold' index. CONCLUSIONS: We constructed an NIQ that correlates highly with Wechsler FSIQ. Tests required to obtain NIQ are commonly used and can be administered in about 45 min. Validity properties of NIQ and W-FSIQ are similar. The NIQ bore greater resemblance to a 'no-hold' than 'hold' index. One can obtain a reasonably accurate estimate of current Full Scale IQ without formal intelligence testing from a brief neuropsychological battery.

Relationship of mindful awareness to neural processing of angry faces and impact of mindfulness training: A pilot investigation.

Mindfulness is paying attention, non-judgmentally, to experience in the moment. Mindfulness training reduces depression and anxiety and influences neural processes in midline self-referential and lateralized somatosensory and executive networks. Although mindfulness benefits emotion regulation, less is known about its relationship to anger and the corresponding neural correlates. This study examined the relationship of mindful awareness and brain hemodynamics of angry face processing, and the impact of mindfulness training. Eighteen healthy volunteers completed an angry face processing fMRI paradigm and measurement of mindfulness and anger traits. Ten of these participants were recruited from a Mindfulness-Based Stress Reduction (MBSR) class and also completed imaging and other assessments post-training. Self-reported mindful awareness increased after MBSR, but trait anger did not change. Baseline mindful awareness was negatively related to left inferior parietal lobule activation to angry faces; trait anger was positively related to right middle frontal gyrus and bilateral angular gyrus. No significant pre-post changes in angry face processing were found, but changes in trait mindful awareness and anger were associated with sub-threshold differences in paralimbic activation. These preliminary and hypothesis-generating findings, suggest the analysis of possible impact of mindfulness training on anger may begin with individual differences in angry face processing.

Therapeutic relationship in the treatment of geriatric depression with executive dysfunction.

BACKGROUND: The effects of therapeutic relationship (TR) in elder mental health are understudied. A greater understanding of TR in geriatric psychotherapy is particularly needed for treating late-life depression with executive dysfunction, which predicts poor response to antidepressant medication and presents unique clinical challenges. METHODS: Participants were older patients (N = 220) with major depression and executive dysfunction who received 12 weeks of problem-solving therapy or supportive therapy in a randomized control trial. Multilevel growth curve modeling and latent change scores were used to analyze TR dimensions of Understanding and Accepting at the patient level (individual patient ratings, N = 194) and therapist level (ratings of each therapist averaged across participants, N = 10). RESULTS: TR predicted reduction of depression in both treatment groups, while treatment×TR interactions were not significant. Patients treated by therapists with higher average Understanding (patient and therapist level) and Accepting (therapist level) ratings had greater decreases in depression. The patient level×therapist level interaction for Understanding approached statistical significance (p=.065), suggesting a synergistic effect on treatment outcome. Together, Understanding and Accepting predicted 21% of variance in depression level changes. LIMITATIONS: TR was not assessed throughout the course of treatment (only after the first therapy session and at post-treatment) and did not include ratings from an objective evaluator. CONCLUSIONS: Assessment of patient's experience of the TR and of therapist ability to foster Understanding and Accepting can play a significant role in the delivery of geriatric psychosocial interventions.

Assessing the dysexecutive syndrome in dementia.

OBJECTIVE: We compared performance on tests of dysexecutive behaviour (DB) and executive function (EF) in patients with behavioural variant frontotemporal dementia (bvFTD), primary progressive aphasia (PPA) and corticobasal syndrome (CBS). METHODS: Patients diagnosed with bvFTD (n=124), PPA (n=34) and CBS (n=85) were recruited. EF was measured with the Delis-Kaplan Executive Function System (DKEFS: performance based), and DB was measured with the Frontal Systems Behavior Scale (FrSBe: caregiver-report based). Confirmatory factor analysis characterised the relationship between EF and DB, binary logistic regression evaluated the incremental diagnostic utility of the measures and neuroimaging data from 110 patients identified neural correlates. RESULTS: EF was lowest and DB was highest in bvFTD participants. EF and DB were distinct but related (r=-0.48). Measures correctly classified 89% of bvFTD from CBS patients and 93% of bvFTD from PPA patients-30% and 13% above base rates (59%, 80%), respectively. All modalities were useful in identifying CBS and PPA, whereas DB alone was useful for identifying bvFTD. EF was uniquely associated with caudal left dorsolateral prefrontal and lateral temporo-parietal cortices. DB was uniquely associated with the cingulate (R>L), right subcallosal and right anterior frontal cortex. EF and DB were associated with the rostral dorsolateral prefrontal cortex bilaterally. CONCLUSIONS: EF and DB measures displayed criterion and construct validity, had incremental utility at low DB levels (CBS and PPA) and were associated with overlapping and distinct neural correlates. EF and DB procedures can conjointly provide useful diagnostic and descriptive information in identifying and ruling out the dysexecutive syndrome.

Role of Executive Dysfunction and Dysexecutive Behavior in Late-Life Depression and Disability.

OBJECTIVE: Both executive dysfunction (ED), measured by performance-based tasks, and dysexecutive behavior (DB), measured by behavioral rating scales, contribute to late-life depression and comorbid disability. There is a modest positive association of ED and DB, but less is known about their relative contributions to core aspects of neuropsychiatric conditions and whether they provide unique or redundant information. METHODS: Latent variable analyses were applied to ED, DB, depression, and disability data from 220 older patients with major depression and ED who had been enrolled in a psychosocial treatment study of depression. ED measures included the Trail Making Test, part B, Stroop Color Word Interference Test, and Hopkins Verbal Learning Test-Trail 1. The ED scale from the Frontal Systems Behavior Scale, self and other-rated, served as the ratings-based measure of DB. RESULTS: The measurement model, with all four latent variables related to one another, demonstrated good fit (RMSEA=0.06). In the structural models, DB was associated with both depression (ß=0.61) and disability (ß=0.42), whereas ED was associated with depression (ß=0.43) but not disability (ß=0.16). Social problem-solving accounted for 49% of the influence of DB on late-life depression, whereas ED was not related to social problem-solving. CONCLUSION: ED and the lesser studied DB measures offer unique and complementary information. DB was robustly associated with late-life depression and disability. Patients with depression and ED may be more likely to develop disability when they exhibit DB and social problem-solving difficulties.

Cognitive estimation and its assessment.

PURPOSE: We evaluated the internal consistency and construct and criterion validity of a 10-item revision of the Cognitive Estimation Task (CET-R) developed by Shallice and Evans to assess problem-solving hypothesis generation. METHOD: The CET-R was administered to 216 healthy adults from the Aging, Brain Imaging, and Cognition study and 57 adult outpatients with schizophrenia. RESULTS: Exploratory and confirmatory factor analysis (EFA and CFA) of the healthy sample revealed that seven of the 10 CET-R items constitute a more internally consistent scale (CET-R-7). Though EFA indicated that two CET-R-7 dimensions might be present (length and speed/time estimation, respectively), CFA confirmed that a single factor best represents the seven items. The CET-R-7 was modeled best by crystallized intelligence, adequately by fluid intelligence, and inadequately by visuospatial problem solving. Performance on the CET-R-7 correlated significantly with the neuropsychological domains of speed and fluency, but not memory or executive function. Finally, CET-R performance differed by diagnosis, sex, and education, but not age. CONCLUSIONS: This study identified an internally consistent set of items that measures the construct of cognitive estimation. This construct relates to several important dimensions of psychological functioning, including crystallized and fluid intelligence, generativity, and self-monitoring. It also is sensitive to cognitive dysfunction in adults with schizophrenia.

Functional anatomic dissociation of description and picture naming in the left temporal lobe.

Functional magnetic resonance imaging (fMRI) was used in a non-patient experimental sample to assess the neuroanatomical dissociation of picture and description naming (PN and DN) in temporal lobe (TL). The purpose was to determine the generalizability of findings in semantic organization in the epilepsy patient population to the broader population. It was hypothesized that, akin to patient derived findings, DN would uniquely activate left TL regions anterior to those associated with PN, while overlapping in middle and posterior left TL. Participants (n = 16) underwent fMRI while silently naming target words during a picture naming task (PNT; line drawings) and description naming task (DNT; orthographic phrases). Analysis was a priori restricted to the left TL. Group results of direct contrasts (DNT > PNT and PNT > DNT) confirmed the hypothesized dissociation with DNT > PNT activating anterior left TL. Within-condition contrasts (DNT and PNT alone) yielded additional support, revealing areas of shared and unique activation in each condition. This is the first imaging study to contrast DN and PN in the same sample. The results suggest DN and PN are meaningfully different constructs subserved by converging and diverging TL neuroanatomy and may be differentially affected by disease.

Social cognition deficits and associations with drinking history in alcoholic men and women.

BACKGROUND: Previous studies have demonstrated the presence of a social cognition factor as an element of general cognition in healthy control and clinical populations. Recently developed measures of social cognition include the social perception and faces subtests of the Wechsler Advanced Clinical Solutions (ACS) Social Cognition module. While these measures have been validated on various clinical samples, they have not been studied in alcoholics. Alcoholism has been associated with emotional abnormalities and diminished social cognitive functioning as well as neuropathology of brain areas underlying social processing abilities. We used the ACS Social Perception and Faces subtests to assess alcoholism-related impairments in social cognition. METHODS: Social cognitive functioning was assessed in 77 abstinent alcoholic individuals (37 women) and 59 nonalcoholic control participants (29 women), using measures of the ACS Social Cognition module and subtests of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) that contain a social cognition component (Picture Completion and Comprehension). Group and gender differences in ACS and WAIS-IV performance were assessed, as well as relationships between measures of alcoholism severity and social cognitive functioning. RESULTS: Alcoholics performed significantly worse than nonalcoholics on the ACS measures of Affect Naming and Faces Content. Alcoholic men were impaired relative to alcoholic women on Prosody Face Matching and Faces Content scores. Among alcoholics, longer durations of heavy drinking were associated with poorer performance on Affect Naming, and a greater number of daily drinks were associated with lower Prosody Face Matching performance. For alcoholic women, a longer duration of abstinence was associated with better performance on Affect Naming. CONCLUSIONS: Alcoholic men and women showed different patterns of associations between alcoholism indices and clinically validated social cognition assessments. These findings extend into the social cognition domain, previous literature demonstrating the presence of cognitive deficits in alcoholism, their association with alcoholism severity, and variability by gender. Moreover, because impairments in social cognition can persist despite extended abstinence, they have important implications for relapse prevention.

Convergence and divergence of neuroanatomic correlates and executive task performance in healthy controls and psychiatric participants.

The associations between brain matter volume in the cerebral cortex and set shifting and attentional control as operationalized by the Wisconsin Card Sort Test (WCST) and Condition Three of the Delis-Kaplan version of the Color Word Interference Test (CWIT) were investigated in 15 healthy controls and 16 heterogeneously diagnosed psychiatric patients with self-control problems using voxel based morphometry. Both groups underwent standardized magnetic resonance imaging and neuropsychological assessment. WCST and CWIT variables, and a composite, were regressed across the whole brain. Although CWIT performance levels were the same in both groups, neuroanatomic correlates for the psychiatric participants invoked the left hemisphere language system, but the bilateral dorsal attention system in the healthy controls. On its own, no neuroanatomic correlates were observed for the WCST. But when part of a composite with CWIT, neuroanatomic correlates in the dorsal attention system emerged for the psychiatric participants. Psychometric combinations of manifest executive task variables may best represent higher level latent neuro-cognitive control systems. Factor analytic studies of neuropsychological test performances suggest the constructs being measured are the same across psychiatric and non-diagnosed participants, however, imaging modalities indicate the relevant neural architecture can vary by group.

Dorsal/ventral parcellation of the amygdala: relevance to impulsivity and aggression.

Investigations into the specific association of amygdala volume, a critical aspect of the fronto-limbic emotional circuitry, and aggression have produced results broadly consistent with the 'larger is more powerful' doctrine. However, recent reports suggest that the ventral and dorsal aspects of the amygdala play functionally specific roles, respectively, in the activation and control of behavior. Therefore, parceling amygdala volume into dorsal and ventral components might prove productive in testing hypotheses regarding volumetric association to aggression, and impulsivity, a related aspect of self-control. We sought to test this hypothesis in a group of 41 psychiatric patients who received standard magnetic resonance imaging and a psychometric protocol including aggression and impulsivity measures. Whole amygdala volumes were not associated with aggression or impulsivity, but significant correlations were found when dorsal/ventral amygdalae were analyzed separately. Specifically, left and right ventral amygdala volume was positively associated with motor impulsivity, and left dorsal amygdala was negatively associated with aggression. Results are discussed in terms of an activation and control model of brain-behavior relations. Potential relevance to the continuum of amygdala hyper- to hypo-activation and aggression is discussed.

Hierarchical organization of cortical morphology of decision-making when deconstructing Iowa Gambling Task performance in healthy adults.

The Iowa Gambling Task (IGT) is a measure of decision-making, in which alternative metrics have greater construct validity than conventional metrics. No large scale study has examined the neural correlates in healthy adults. We administered the IGT and structural MRI to 124 healthy participants. We analyzed the conventional IGT metric of advantageous minus disadvantageous choices (i.e., decks C + D minus decks A + B), and three alternative metrics based on choices from decks D and A alone, and all selections from each deck. Using regression and voxel-based morphometry, we examined regional gray matter volumes as predictors of IGT performance. No neural correlates of the conventional metric emerged, and the neural correlates of individual deck selections were disparate from one another. Alternative metrics showed expected neural correlates of decision-making in prefrontal cortex, insula, thalamus, and other regions. IGT alternative metrics have neural correlates consistent with decision-making theory as those difference scores reduce heterogeneity in cognitive processes. The CD-AB metric construct failure may reflect an artificial amalgamation of processes. The D-A metric appears to more successfully combine multiple levels of representation (dorsolateral prefrontal cortex, sub-cortical, cerebellar).

Does the iowa gambling task measure executive function?

The Iowa Gambling Task (IGT) is assumed to measure executive functioning, but this has not been empirically tested by means of both convergent and discriminant validity. We used structural equation modeling (SEM) to test whether the IGT is an executive function (EF) task (convergent validity) and whether it is not related to other neuropsychological domains (discriminant validity). Healthy community-dwelling participants (N = 214) completed a comprehensive neuropsychological battery. We analyzed the conventional IGT metric and three alternative metrics based on the overall difference of advantageous minus disadvantageous choices made during the last 60 IGT responses and advantageous minus disadvantageous choices based on two specific decks of cards (D minus A). An a priori six-factor hierarchical model of neuropsychological functioning was confirmed with SEM. Attention and processing speed were grouped as "non-associative" factors. Fluency, executive functioning, visual learning/memory, and verbal learning/memory were grouped as higher-level "associative" factors. Of the non-associative factors, attention, but not speed, predicted IGT performance. When each associative factor was entered along with attention, only EF improved the model fit and that was only for metrics based on trials 41-100. SEM indicates metrics based on trails 1-100 are influenced by attention, and metrics based on trails 41-100 are influenced by attention and EF. Its associative strength with attention is twice that of EF. Conceptually, the IGT is a multi-trait task involving novel problem-solving and attentional domains to a greater extent, and executive functioning to a lesser extent.