Bimodal Virtual Reality Stroop for Assessing Distractor Inhibition in Autism Spectrum Disorders

Executive functioning deficits found in college students with ASD may have debilitating effects on their everyday activities. Although laboratory studies tend to report unimpaired inhibition in autism, studies of resistance to distractor inhibition reveal difficulties. In two studies, we compared a Virtual Classroom task with paper-and-pencil and computerized Stroop modalities in typically developing individuals and individuals with ASD. While significant differences were not observed between ASD and neurotypical groups on the paper-and-pencil and computerized task, individuals with ASD performed significantly worse on the virtual task with distractors. Findings suggest the potential of the Virtual Classroom Bimodal Stroop task to distinguish between prepotent response inhibition (non-distraction condition) and resistance to distractor inhibition (distraction condition) in adults with high functioning autism.

Evaluation of the Relationship between Brain-Derived Neurotropic Factor Levels and the Stroop Interference Effect in Children with Attention-Deficit Hyperactivity Disorder

INTRODUCTION

Brain-derived neurotropic factor (BDNF) has been suggested to play a role in the pathogenesis of attention-deficit hyperactivity disorder (ADHD). In addition, impairment in executive functions has been reported in children with ADHD. This study investigated the presence of a relationship between Stroop test scores and BDNF levels in children with ADHD.

METHODS

The study was conducted in the Department of Child Psychiatry at Dicle University. The study included 49 children between 6 and 15 years of age (M/F: 42/7), who were diagnosed with ADHD according to DSM-IV, and who did not receive previous therapy. Similar in terms of age and gender to the ADHD group, 40 children were selected in the control group. The Kiddie Schedule for Affective Disorders and Schizophrenia, Present and Lifetime version was administered to all participants. Parents and teachers were administered Turgay DSM-IV-based Child and Adolescent Behavior Disorders Screening and Rating Scale to measure symptom severity in children with ADHD. Children with ADHD underwent the Stroop test. BDNF levels were evaluated in serum by ELISA.

RESULTS

The ADHD and control groups did not differ in terms of BDNF levels. BDNF levels did not differ between ADHD subtypes. There was also no relationship between the Stroop test interference scores and BDNF levels.

CONCLUSION

The findings of the present study are in line with those in studies that demonstrated no significant role of BDNF in the pathogenesis of ADHD.

Using two web-based addiction Stroops to measure the attentional bias in adults with Internet Gaming Disorder

Background and aims People with substance abuse and pathological gamblers show an attentional bias. In a laboratory setting, we found an attentional bias using an addiction Stroop in adults with Internet Gaming Disorder (IGD). We aimed at investigating this effect using two web-based experiments. Methods Study 1: Gamers with IGD, casual gamers, and non-gamers (N = 81, 28.1 ± 7.8 years) completed a web-based addiction Stroop with a fully randomized word order. They saw computer-related and neutral words in four colors and indicated the word color via keypress. Study 2: Gamers with IGD, casual gamers, and non-gamers (N = 87, 23.4 ± 5.1 years) completed a web-based addiction Stroop and a classical Stroop (incongruent color and neutral words), which both had a block design. We expected that in both studies, only the gamers with IGD would react more slowly to computer-related words in the addiction Stroop. All groups were expected to react more slowly to incongruent color words in the classical Stroop. Results In neither study did the gamers with IGD differ in their reaction times to computer-related words compared to neutral words. In Study 2, all groups reacted more slowly to incongruent color words than to neutral words confirming the validity of the online reaction time assessment. Discussion Gamers with IGD did not show a significant attentional bias. IGD may differ from substance abuse and pathological gambling in this respect; alternatively experimenting on the Internet may have introduced error variance that made it harder to detect a bias.

Shape and color naming are inherently asymmetrical: Evidence from practice-based interference

Stroop interference is characterized by strong asymmetry between word and color naming such that the former is faster and interferes with the latter but not vice versa. This asymmetry is attributed to differential experience with naming in the two dimensions, i.e., words and colors. Here we show that training on visual-verbal paired associate tasks equivalent to color and shape naming, not involving word reading, leads to strongly asymmetric interference patterns. In two experiments adults practiced naming colors and shapes, one dimension more extensively (10days) than the other (2days), depending on group assignment. One experiment used novel shapes (ideograms) and the other familiar geometric shapes, associated with nonsense syllables. In a third experiment participants practiced naming either colors or shapes using cross-category shape and color names, respectively, for 12days. Across experiments, despite equal training of the two groups in naming the two different dimensions, color naming was strongly affected by shape even after extensive practice, whereas shape naming was resistant to interference. To reconcile these findings with theoretical accounts of interference, reading may be conceptualized as involving visual-verbal associations akin to shape naming. An inherent or early-developing advantage for naming shapes may provide an evolutionary substrate for the invention and development of reading.

Is semantic activation from print capacity limited? Evidence from the psychological refractory period paradigm

A widely accepted belief across a range of subfields in psychology is that print activates semantics "automatically" in some sense. One such sense is that activating semantics does not require capacity. This view is assessed here in the context of the Psychological Refractory Period (PRP) paradigm because it provides a way of determining whether semantic activation requires a form of capacity. Task 1 was tone classification. Task 2 was Stroop color naming. The distractors consisted of color words on some trials (e.g., BLUE), and semantic associates on others (e.g., TOMATO). Both types of distractors yielded a pattern of data inconsistent with the widespread view that semantic activation is capacity free.

Neural correlates of verbal joint action: ERPs reveal common perception and action systems in a shared-Stroop task

Recent social-cognitive research suggests that the anticipation of co-actors' actions influences people's mental representations. However, the precise nature of such representations is still unclear. In this study we investigated verbal joint representations in a delayed Stroop paradigm, where each participant responded to one color after a short delay. Participants either performed the task as a single actor (single-action, Experiment 1), or they performed it together (joint-action, Experiment 2). We investigated effects of co-actors' actions on the ERP components associated with perceptual conflict (Go N2) and response selection (P3b). Compared to single-action, joint-action reduced the N2 amplitude congruency effect when participants had to respond (Go trials), indicating that representing a co-actor's utterance helped to dissociate action codes and attenuated perceptual conflict for the responding participant. Yet, on NoGo trials the centro-parietal P3 (P3b) component amplitude increased for joint-action, suggesting that participants mapped the stimuli onto the co-actor's upcoming response as if it were their own response. We conclude that people represent others' utterances similarly to the way they represent their own utterances, and that shared perception-action codes for self and others can sometimes reduce, rather than enhance, perceptual conflict.

Novel Symbol Learning-Induced Stroop Effect: Evidence for a Strategy-Based, Utility Learning Model

The automaticity level and attention priority/strategy are two major theories that have attempted to explain the mechanism underlying the Stroop effect. Training is an effective way to manipulate the experience with the two dimensions (ink color and color word) in the Stroop task. In order to distinguish the above two factors (the automaticity or attention/strategy), we revised the training paradigm of MacLeod's study (J Exp Psychol Learn Mem Cogn 14(1):126-135, 1988) by adding a control condition for the Stroop task on Chinese. We found that with training, the changing pattern for the Stroop effect was similar in Stroop tasks in novel symbols and in Chinese, showing markedly increasing interference and marginally decreasing facilitation. The current findings support the strategy-based learning account at early stages of novel learning of written symbols.

Comparison of brain activation patterns during executive function tasks in hoarding disorder and non-hoarding OCD

We examined differences in regional brain activation during tests of executive function in individuals with Hoarding Disorder (HD), Obsessive Compulsive Disorder (OCD), and healthy controls (HC) using functional magnetic resonance imaging (fMRI). Participants completed computerized versions of the Stroop and Go/No-Go task. We found that during the conflict monitoring and response inhibition condition in the Go/No-Go task, individuals with HD had significantly greater activity than controls in the anterior cingulate cortex (ACC) and right dorsolateral prefrontal cortex (DLPFC). HD also exhibited significantly greater right DLPFC activity than OCD. We also observed significant differences in activity between HD and HC and between HD and OCD in regions (ACC, anterior insula, orbitofrontal cortex, and striatum) involved in evaluating stimulus-response-reward associations, or the personal and task-relevant value of stimuli and behavioral responses to stimuli. These results support the hypothesis that individuals with HD have difficulty deciding on the value or task relevance of stimuli, and may perceive an abnormally high risk of negative feedback for difficult or erroneous cognitive behavior.

The Time Course of Activity within the Dorsal and Rostral-Ventral Anterior Cingulate Cortex in the Emotional Stroop Task

Growing evidence from neuroimaging studies suggest that emotional and cognitive processes are interrelated. Anatomical key structures in this context are the dorsal and rostral-ventral anterior cingulate cortex (dACC and rvACC). However, up to now, the time course of activations within these regions during emotion-cognition interactions has not been disentangled. In the present study, we used event-related potentials (ERP) and standardized low-resolution electromagnetic tomography (sLORETA) region of interest (ROI) source localization analyses to explore the time course of neural activations within the dACC and rvACC using a modified emotional Stroop paradigm. ERP components related to Stroop conflict (N200, N450 and late negativity) were analyzed. The time course of brain activations in the dACC and rvACC was strikingly different with more pronounced initial responses in the rvACC followed by increased dACC activity mainly at the late negativity window. Moreover, emotional valence modulated the earlier N450 stage within the rvACC region with higher neural activations in the positive compared to the negative and neutral conditions. Emotional arousal modulated the late negativity stage; firstly in the significant arousal × congruence ERP effect and then the significant higher current density in the low arousal condition within the dACC. Using sLORETA source localization, substantial differences in the activation time courses in the dACC and rvACC could be found during the emotional Stroop task. We suggest that during late negativity, within the dACC, emotional arousal modulated the processing of response conflict, reflected in the correlation between the ex-Gaussian µ and the current density in the dACC.

The Role of Phonological Processing in Semantic Access of Chinese Characters: A Near-Infrared Spectroscopy Study

The Stroop task was used to investigate the role of phonological processing in semantic access for written Chinese language. Fourteen children were recruited to perform the Stroop task, using color characters, their homophones and neutral characters as stimuli. Near-infrared spectroscopy (NIRS) was used to measure the brain activation in the prefrontal cortex (PFC) during the task. In view of better sensitivity, oxy-hemoglobin was chosen to indicate the task activation. In behavioral performance, there was a significant classical Stroop interference effect as indexed by longer response time and higher error rate for the color task than the neutral task, whereas there was no evident interference effect for the color homophones. The NIRS data agreed with the behavioral data, and showed a significant Stroop effect only for the color characters in the bilateral PFC. These results suggested that phonology may not play an important role in semantic activation of Chinese characters for children.

Compensatory Neural Activity in Response to Cognitive Fatigue

Prolonged continuous performance of a cognitively demanding task induces cognitive fatigue and is associated with a time-related deterioration of objective performance, the degree of which is referred to cognitive fatigability. Although the neural underpinnings of cognitive fatigue are poorly understood, prior studies report changes in neural activity consistent with deterioration of task-related networks over time. While compensatory brain activity is reported to maintain motor task performance in the face of motor fatigue and cognitive performance in the face of other stressors (e.g., aging) and structural changes, there are no studies to date demonstrating compensatory activity for cognitive fatigue. High-density electroencephalography was recorded from human subjects during a 160 min continuous performance of a cognitive control task. While most time-varying neural activity showed a linear decline over time, we identified an evoked potential over the anterior frontal region which demonstrated an inverted U-shaped time-on-task profile. This evoked brain activity peaked between 60 and 100 min into the task and was positively associated with better behavioral performance only during this interval. Following the peak and during subsequent decline of this anterior frontal activity, the rate of performance decline also accelerated. These findings demonstrate that this anterior frontal brain activity, which is not part of the primary task-related activity at baseline, is recruited to compensate for fatigue-induced impairments in the primary task-related network, and that this compensation terminates as cognitive fatigue further progresses. These findings may be relevant to understanding individual differences in cognitive fatigability and developing interventions for clinical conditions afflicted by fatigue.

SIGNIFICANCE STATEMENT

Fatigue refers to changes in objective performance and subjective effort induced by continuous task performance. We examined the neural underpinnings of cognitive fatigue in humans using a prolonged continuous performance task and high-density electroencephalography with the goal of determining whether compensatory processes exist to maintain performance in the face of fatigue. We identified brain activity demonstrating an inverted U-shaped time-on-task profile. This brain activity showed features consistent with a compensatory role including: peaking between 60 and 100 min into the task, a positive association with behavioral performance only during this interval, and accelerated performance decline following its peak. These findings may be relevant to understanding individual differences in cognitive fatigue and developing interventions for clinical conditions afflicted by fatigue.

A cognitive fMRI study in non-manifesting LRRK2 and GBA carriers

Mutations in the GBA and LRRK2 genes account for one-third of the prevalence of Parkinson's disease (PD) in Ashkenazi Jews. Non-manifesting carriers (NMC) of these mutations represent a population at risk for future development of PD. PD patient who carry mutations in the GBA gene demonstrates more significant cognitive decline compared to idiopathic PD patients. We assessed cognitive domains using fMRI among NMC of both LRRK2 and GBA mutations to better understand pre-motor cognitive functions in these populations. Twenty-one LRRK2-NMC, 10 GBA-NMC, and 22 non-manifesting non-carriers (NMNC) who participated in this study were evaluated using the standard questionnaires and scanned while performing two separate cognitive tasks; a Stroop interference task and an N-Back working memory task. Cerebral activation patterns were assessed using both whole brain and predefined region of interest (ROI) analysis. Subjects were well matched in all demographic and clinical characteristics. On the Stroop task, in spite of similar behavior, GBA-NMC demonstrated increased task-related activity in the right medial frontal gyrus and reduced task-related activity in the left lingual gyrus compared to both LRRK2-NMC and NMNC. In addition, GBA-NMC had higher activation patterns in the incongruent task compared to NMNC in the left medial frontal gyrus and bilateral precentral gyrus. No whole-brain differences were noted between groups on the N-Back task. Paired cognitive and task-related performance between GBA-NMC, LRRK2-NMC, and NMNC could indicate that the higher activation patterns in the incongruent Stroop condition among GBA-NMC compared to LRRK2-NMC and NMNC may represent a compensatory mechanism that enables adequate cognitive performance.

Ventral striatal hyperconnectivity during rewarded interference control in adolescents with ADHD

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) is characterized by cognitive deficits (e.g., interference control) and altered reward processing. Cognitive control is influenced by incentive motivation and according to current theoretical models, ADHD is associated with abnormal interactions between incentive motivation and cognitive control. However, the neural mechanisms by which reward modulates cognitive control in individuals with ADHD are unknown.

METHOD

We used event-related functional resonance imaging (fMRI) to study neural responses during a rewarded Stroop color-word task in adolescents (14-17 years) with ADHD (n = 25; 19 boys) and healthy controls (n = 33; 22 boys).

RESULTS

Adolescents with ADHD showed increased reward signaling within the superior frontal gyrus and ventral striatum (VS) relative to controls. Importantly, functional connectivity analyses revealed a hyperconnectivity between VS and motor control regions in the ADHD group, as a function of reward-cognitive control integration. Connectivity was associated with performance improvement in controls but not in the ADHD group, suggesting inefficient connectivity.

CONCLUSION

Adolescents with ADHD show increased neural sensitivity to rewards and its interactions with interference control in VS and motor regions, respectively. The findings support theoretical models of altered reward-cognitive control integration in individuals with ADHD.

Parkinson's disease and the Stroop color word test: processing speed and interference algorithms

OBJECTIVE

Processing speed alters the traditional Stroop calculations of interference. Consequently, alternative algorithms for calculating Stroop interference have been introduced to control for processing speed, and have done so in a multiple sclerosis sample. This study examined how these processing speed correction algorithms change interference scores for individuals with idiopathic Parkinson's disease (PD, n = 58) and non-PD peers (n = 68).

METHOD

Linear regressions controlling for demographics predicted group (PD vs. non-PD) differences for Jensen's, Golden's, relative, ratio, and residualized interference scores. To examine convergent and divergent validity, interference scores were correlated with standardized measures of processing speed and executive function.

RESULTS

PD-non-PD differences were found for Jensen's interference score, but not Golden's score, or the relative, ratio, and residualized interference scores. Jensen's score correlated significantly with standardized processing speed but not executive function measures. Relative, ratio, and residualized scores correlated with executive function but not processing speed measures. Golden's score did not correlate with any other standardized measures.

CONCLUSIONS

The relative, ratio, and residualized scores were comparable for measuring Stroop interference in processing speed-impaired populations. Overall, the ratio interference score may be the most useful calculation method to control for processing speed in this population.

Speed and Lateral Inhibition of Stimulus Processing Contribute to Individual Differences in Stroop-Task Performance

The Stroop task is a popular neuropsychological test that measures executive control. Strong Stroop interference is commonly interpreted in neuropsychology as a diagnostic marker of impairment in executive control, possibly reflecting executive dysfunction. However, popular models of the Stroop task indicate that several other aspects of color and word processing may also account for individual differences in the Stroop task, independent of executive control. Here we use new approaches to investigate the degree to which individual differences in Stroop interference correlate with the relative processing speed of word and color stimuli, and the lateral inhibition between visual stimuli. We conducted an electrophysiological and behavioral experiment to measure (1) how quickly an individual’s brain processes words and colors presented in isolation (P3 latency), and (2) the strength of an individual’s lateral inhibition between visual representations with a visual illusion. Both measures explained at least 40% of the variance in Stroop interference across individuals. As these measures were obtained in contexts not requiring any executive control, we conclude that the Stroop effect also measures an individual’s pre-set way of processing visual features such as words and colors. This study highlights the important contributions of stimulus processing speed and lateral inhibition to individual differences in Stroop interference, and challenges the general view that the Stroop task primarily assesses executive control.

Simultanagnosia: when all you can see are trees, the forest still rules

We investigated the nature of covertly processed visual elements in a patient with simultanagnosia, a disorder characterized by the inability to perceive multiple aspects of a visual scene all at once. Using the first letter of the color words red, green, or blue, we created a novel testing paradigm that combined Navon global-local stimuli with a single-letter Stroop task. The letters R, G, or B were arranged in the overall configuration of a large R, G, or B. The patient never could report seeing the larger letter, and always could name the smaller letters. But, when asked to name ink color only, and ignore letter identity, the large letter covertly affected responding. That is, when the large letter was the same as the first letter of the ink color, the patient named ink color more quickly and accurately than when the large letter was incongruent with the correct response. Moreover, when the covert global and overt local visual processing conflicted, the global letter always dominated over the local letters, despite the patient's inability to perceive it consciously. These data show that the covert processing of global visual information in simultanagnosia can dominate overt local information, even across different streams of information processing.

Acute effects of 3G mobile phone radiations on frontal haemodynamics during a cognitive task in teenagers and possible protective value of Om chanting

Mobile phone induced electromagnetic field (MPEMF) as well as chanting of Vedic mantra 'OM' has been shown to affect cognition and brain haemodynamics, but findings are still inconclusive. Twenty right-handed healthy teenagers (eight males and 12 females) in the age range of 18.25 ± 0.44 years were randomly divided into four groups: (1) MPONOM (mobile phone 'ON' followed by 'OM' chanting); (2) MPOFOM (mobile phone 'OFF' followed by 'OM' chanting); (3) MPONSS (mobile phone 'ON' followed by 'SS' chanting); and (4) MPOFSS (mobile phone 'OFF' followed by 'SS' chanting). Brain haemodynamics during Stroop task were recorded using a 64-channel fNIRS device at three points of time: (1) baseline, (2) after 30 min of MPON/OF exposure, and (3) after 5 min of OM/SS chanting. RM-ANOVA was applied to perform within- and between-group comparisons, respectively. Between-group analysis revealed that total scores on incongruent Stroop task were significantly better after OM as compared to SS chanting (MPOFOM vs MPOFSS), pre-frontal activation was significantly lesser after OM as compared to SS chanting in channel 13. There was no significant difference between MPON and MPOF conditions for Stroop performance, as well as brain haemodynamics. These findings need confirmation through a larger trial in future.

Orthographic Reading Deficits in Dyslexic Japanese Children: Examining the Transposed-Letter Effect in the Color-Word Stroop Paradigm

In orthographic reading, the transposed-letter effect (TLE) is the perception of a transposed-letter position word such as “cholocate” as the correct word “chocolate.” Although previous studies on dyslexic children using alphabetic languages have reported such orthographic reading deficits, the extent of orthographic reading impairment in dyslexic Japanese children has remained unknown. This study examined the TLE in dyslexic Japanese children using the color-word Stroop paradigm comprising congruent and incongruent Japanese hiragana words with correct and transposed-letter positions. We found that typically developed children exhibited Stroop effects in Japanese hiragana words with both correct and transposed-letter positions, thus indicating the presence of TLE. In contrast, dyslexic children indicated Stroop effects in correct letter positions in Japanese words but not in transposed, which indicated an absence of the TLE. These results suggest that dyslexic Japanese children, similar to dyslexic children using alphabetic languages, may also have a problem with orthographic reading.

Limits on the generalizability of context-driven control

Context-driven control refers to the fast and flexible weighting of stimulus dimensions that may be applied at the onset of a stimulus. Evidence for context-driven control comes from interference tasks in which participants encounter a high proportion of incongruent trials at one location and a high proportion of congruent trials at another location. Since the size of the congruency effect varies as a function of location, this suggests that stimulus dimensions are weighted differently based on the context in which they appear. However, manipulations of condition proportion are often confounded by variations in the frequency with which particular stimuli are encountered. To date, there is limited evidence for the context-driven control in the absence of stimulus frequency confounds. In the current paper, we attempt to replicate and extend one such finding [Crump, M. J. C., & Milliken, B. (2009). The flexibility of context-specific control: Evidence for context-driven generalization of item-specific control settings. The Quarterly Journal of Experimental Psychology, 62, 1523-1532]. Across three experiments we fail to find evidence for context-driven control in the absence of stimulus frequency confounds. Based on these results, we argue that consistency in the informativeness of the irrelevant dimension may be required for context-driven control to emerge.

Cognitive flexibility and changes in hopelessness across time: A moderation hypothesis

Prior literature has suggested that cognitive flexibility is implicated in the feeling of hopelessness. However, studies on the nature of their relationship have been scarce. This study posits a moderation hypothesis on the relationship between cognitive flexibility and hopelessness. A total of 78 elderly participants (M_age = 70, SD = 6.1) were administered a self-report measure of hopelessness across two time points approximately 10 months apart and a measure of cognitive flexibility. We hypothesized that baseline hopelessness scores would moderate the relationship between cognitive flexibility and hopelessness scores 10 months later. Specifically, among the high baseline hopelessness group, we predicted that cognitively flexible participants would report lower hopelessness scores 10 months later. However, for the low baseline hopelessness group, cognitive flexibility would be unrelated to hopelessness scores 10 months later. The results of a bootstrapped moderation analysis controlling for age, sex, education, and general cognitive status supported our moderation hypothesis and predictions. These findings reveal the complex nature of the relationship between cognitive flexibility and hopelessness. The implications of these findings in the wider clinical context were discussed.

State anxiety impairs attentional control when other sources of control are minimal

Research suggests anxiety impairs attentional control; however, this effect has been unreliable. We argue that anxiety's impairment of attentional control is subtle, and can be obscured by other non-emotional sources of control. We demonstrate this by examining conflict adaptation, an enhancement in attentional control following a trial with high conflict between distracter and target stimuli. Participants completed a Stroop task featuring incongruent (e.g. RED in green font; high-conflict) and control (e.g. +++ in green font; low-conflict) trials. More state-anxious participants showed greater Stroop interference following control trials, but interference was uniformly low following incongruent trials. This suggests state anxiety can impair attention, but other sources of top-down control - such as conflict adaptation - can easily overcome this impairment. This is consistent with recent theories of anxious cognition and shows that anxiety researchers must attend to the dynamics and sources of attentional control.

Abnormalities of the executive control network in multiple sclerosis phenotypes: An fMRI effective connectivity study

The Stroop interference task is a cognitively demanding task of executive control, a cognitive ability that is often impaired in patients with multiple sclerosis (MS). The aim of this study was to compare effective connectivity patterns within a network of brain regions involved in the Stroop task performance between MS patients with three disease clinical phenotypes [relapsing-remitting (RRMS), benign (BMS), and secondary progressive (SPMS)] and healthy subjects. Effective connectivity analysis was performed on Stroop task data using a novel method based on causal Bayes networks. Compared with controls, MS phenotypes were slower at performing the task and had reduced performance accuracy during incongruent trials that required increased cognitive control. MS phenotypes also exhibited connectivity abnormalities reflected as weaker shared connections, presence of extra connections (i.e., connections absent in the HC connectivity pattern), connection reversal, and loss. In SPMS and the BMS groups but not in the RRMS group, extra connections were associated with deficits in the Stroop task performance. In the BMS group, the response time associated with correct responses during the congruent condition showed a positive correlation with the left posterior parietal → dorsal anterior cingulate connection. In the SPMS group, performance accuracy during the congruent condition showed a negative correlation with the right insula → left insula connection. No associations between extra connections and behavioral performance measures were observed in the RRMS group. These results suggest that, depending on the phenotype, patients with MS use different strategies when cognitive control demands are high and rely on different network connections. Hum Brain Mapp, 37:2293-2304, 2016. © 2016 Wiley Periodicals, Inc.

Does cognitive performance map to categorical diagnoses of schizophrenia, schizoaffective disorder and bipolar disorder? A discriminant functions analysis

OBJECTIVES

Despite known overlaps in the pattern of cognitive impairments in individuals with bipolar disorder (BD), schizophrenia (SZ) and schizoaffective disorder (SZA), few studies have examined the extent to which cognitive performance validates traditional diagnostic boundaries in these groups.

METHOD

Individuals with SZ (n=49), schizoaffective disorder (n=33) and BD (n=35) completed a battery of cognitive tests measuring the domains of processing speed, immediate memory, semantic memory, learning, working memory, executive function and sustained attention.

RESULTS

A discriminant functions analysis revealed a significant function comprising semantic memory, immediate memory and processing speed that maximally separated patients with SZ from those with BD. Initial classification scores on the basis of this function showed modest diagnostic accuracy, owing in part to the misclassification of SZA patients as having SZ. When SZA patients were removed from the model, a second cross-validated classifier yielded slightly improved diagnostic accuracy and a single function solution, of which semantic memory loaded most heavily.

CONCLUSIONS

A cluster of non-executive cognitive processes appears to have some validity in mapping onto traditional nosological boundaries. However, since semantic memory performance was the primary driver of the discrimination between BD and SZ, it is possible that performance differences between the disorders in this cognitive domain in particular, index separate underlying aetiologies.

Assessment of Tobacco-Related Approach and Attentional Biases in Smokers, Cravers, Ex-Smokers, and Non-Smokers

According to theories of addictive behaviors, approach and attentional biases toward smoking-related cues play a crucial role in tobacco dependence. Several studies have investigated these biases by using various paradigms in different sample types. However, this heterogeneity makes it difficult to compare and evaluate the results. The present study aimed to address this problem, via (i) a structural comparison of different measures of approach-avoidance and a measure of smoking-related attentional biases, and (ii) using within one study different representative samples in the context of tobacco dependence. Three measures of approach-avoidance were employed: an Approach Avoidance Task (AAT), a Stimulus Response Compatibility Task (SRC), and a Single Target Implicit Association Test (ST-IAT). To assess attentional biases, a modified Stroop task including smoking-related words was administered. The study included four groups: n = 58 smokers, n = 57 non-smokers, n = 52 cravers, and n = 54 ex-smokers. We expected to find strong tobacco-related approach biases and attentional biases in smokers and cravers. However, the general pattern of results did not confirm these expectations. Approach responses assessed during the AAT and SRC did not differ between groups. Moreover, the Stroop did not show the expected interference effect. For the ST-IAT, cravers had stronger approach associations toward smoking-related cues, whereas non-smokers showed stronger avoidance associations. However, no such differences in approach-avoidance associations were found in smokers and ex-smokers. To conclude, these data do not provide evidence for a strong role of implicit approach and attentional biases toward smoking-related cues in tobacco dependency.

The influence of negative urgency, attentional bias, and emotional dimensions on palatable food consumption

We tested a theoretical model concerning the role of attentional bias and negative affect in food consumption that offers important advances. We hypothesized that the effects of negative affect manipulations on food consumption vary as a function of trait levels of negative urgency (NU; tendency to act impulsively when distressed), and attentional bias and that the roles of emotional arousal and negative emotional valence differ and should be studied separately. 190 undergraduate women were randomly assigned to either an anger or neutral mood condition. Women in both conditions completed the Food Stroop, in which the presentation of food and neutral words were counterbalanced. After the task, participants were given the opportunity to eat mandarin oranges and/or chocolate candy while the experimenter was out of the room. The type and quantity of food consumed was counted after the participant departed. As hypothesized, the roles of emotional arousal and valence differed and the effect of the induced emotion was moderated by NU. Women high in NU who experienced emotional arousal were more likely to eat candy and consumed more candy than other women. Emotional valence had no effect on candy consumption. Neither increases in emotional arousal or emotional valence influenced attentional bias to food cues. Attentional bias was also unrelated to food consumption. The impact of negative mood inductions on palatable food consumption appears to operate through emotional arousal and not negative emotional valence, and it may operate primarily for women high in NU.

The neural dynamics of stimulus and response conflict processing as a function of response complexity and task demands

Both stimulus and response conflict can disrupt behavior by slowing response times and decreasing accuracy. Although several neural activations have been associated with conflict processing, it is unclear how specific any of these are to the type of stimulus conflict or the amount of response conflict. Here, we recorded electrical brain activity, while manipulating the type of stimulus conflict in the task (spatial [Flanker] versus semantic [Stroop]) and the amount of response conflict (two versus four response choices). Behaviorally, responses were slower to incongruent versus congruent stimuli across all task and response types, along with overall slowing for higher response-mapping complexity. The earliest incongruency-related neural effect was a short-duration frontally-distributed negativity at ~200 ms that was only present in the Flanker spatial-conflict task. At longer latencies, the classic fronto-central incongruency-related negativity 'N(inc)' was observed for all conditions, but was larger and ~100 ms longer in duration with more response options. Further, the onset of the motor-related lateralized readiness potential (LRP) was earlier for the two vs. four response sets, indicating that smaller response sets enabled faster motor-response preparation. The late positive complex (LPC) was present in all conditions except the two-response Stroop task, suggesting this late conflict-related activity is not specifically related to task type or response-mapping complexity. Importantly, across tasks and conditions, the LRP onset at or before the conflict-related N(inc), indicating that motor preparation is a rapid, automatic process that interacts with the conflict-detection processes after it has begun. Together, these data highlight how different conflict-related processes operate in parallel and depend on both the cognitive demands of the task and the number of response options.

Better cognitive control of emotional information is associated with reduced pro-inflammatory cytokine reactivity to emotional stress

Stress is strongly associated with several mental and physical health problems that involve inflammation, including asthma, cardiovascular disease, certain types of cancer, and depression. It has been hypothesized that better cognitive control of emotional information may lead to reduced inflammatory reactivity to stress and thus better health, but to date no studies have examined whether differences in cognitive control predict pro-inflammatory cytokine responses to stress. To address this issue, we conducted a laboratory-based experimental study in which we randomly assigned healthy young-adult females to either an acute emotional stress (emotionally evocative video) or no-stress (control video) condition. Salivary levels of the key pro-inflammatory cytokines IL-1β, IL-6, and IL-8 were measured before and after the experimental manipulation, and following the last cytokine sample, we assessed participants' cognitive control of emotional information using an emotional Stroop task. We also assessed participants' cortisol levels before and after the manipulation to verify that documented effects were specific to cytokines and not simply due to increased nonwater salivary output. As hypothesized, the emotional stressor triggered significant increases in IL-1β, IL-6, and IL-8. Moreover, even in fully adjusted models, better cognitive control following the emotional (but not control) video predicted less pronounced cytokine responses to that stressor. In contrast, no effects were observed for cortisol. These data thus indicate that better cognitive control specifically following an emotional stressor is uniquely associated with less pronounced pro-inflammatory cytokine reactivity to such stress. These findings may therefore help explain why superior cognitive control portends better health over the lifespan.

Stroop interference associated with efficient reading fluency and prelexical orthographic processing

The Stroop Color-Word Test involves a dynamic interplay between reading and executive functioning that elicits intuitions of word reading automaticity. One such intuition is that strong reading skills (i.e., more automatized word reading) play a disruptive role within the test, contributing to Stroop interference. However, evidence has accumulated that challenges this intuition. The present study examined associations among Stroop interference, reading skills (i.e., isolated word identification, grapheme-to-phoneme mapping, phonemic awareness, reading fluency) measured on standardized tests, and orthographic skills measured on experimental computerized tasks. Among university students (N = 152), correlational analyses showed greater Stroop interference to be associated with (a) relatively low scores on all standardized reading tests, and (b) longer response latencies on orthographic tasks. Hierarchical regression demonstrated that reading fluency and prelexical orthographic processing predicted unique and significant variance in Stroop interference beyond baseline rapid naming. Results suggest that strong reading skills, including orthographic processing, play a supportive role in resolving Stroop interference.

The Role of Intelligence Quotient and Emotional Intelligence in Cognitive Control Processes

The relationship between intelligence quotient (IQ) and cognitive control processes has been extensively established. Several studies have shown that IQ correlates with cognitive control abilities, such as interference suppression, as measured with experimental tasks like the Stroop and Flanker tasks. By contrast, there is a debate about the role of Emotional Intelligence (EI) in individuals' cognitive control abilities. The aim of this study is to examine the relation between IQ and EI, and cognitive control abilities evaluated by a typical laboratory control cognitive task, the Stroop task. Results show a negative correlation between IQ and the interference suppression index, the ability to inhibit processing of irrelevant information. However, the Managing Emotions dimension of EI measured by the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT), but not self-reported of EI, negatively correlates with the impulsivity index, the premature execution of the response. These results suggest that not only is IQ crucial, but also competences related to EI are essential to human cognitive control processes. Limitations and implications of these results are also discussed.

The impact of initiation: Early onset marijuana smokers demonstrate altered Stroop performance and brain activation

Marijuana (MJ) use is on the rise, particularly among teens and emerging adults. This poses serious public health concern, given the potential deleterious effects of MJ on the developing brain. We examined 50 chronic MJ smokers divided into early onset (regular MJ use prior to age 16; n=24) and late onset (age 16 or later; n=26), and 34 healthy control participants (HCs). All completed a modified Stroop Color Word Test during fMRI. Results demonstrated that MJ smokers exhibited significantly poorer performance on the Interference subtest of the Stroop, as well as altered patterns of activation in the cingulate cortex relative to HCs. Further, early onset MJ smokers exhibited significantly poorer performance relative to both HCs and late onset smokers. Additionally, earlier age of MJ onset as well as increased frequency and magnitude (grams/week) of MJ use were predictive of poorer Stroop performance. fMRI results revealed that while late onset smokers demonstrated a more similar pattern of activation to the control group, a different pattern was evident in the early onset group. These findings underscore the importance of assessing age of onset and patterns of MJ use and support the need for widespread education and intervention efforts among youth.

The effect of orthographic and emotional neighbourhood in a colour categorization task

This study investigated whether and how the strength of reading interference in a colour categorization task can be influenced by lexical competition and the emotional characteristics of words not directly presented. Previous findings showed inhibitory effects of high-frequency orthographic and emotional neighbourhood in the lexical decision task. Here, we examined the effect of orthographic neighbour frequency according to the emotional valence of the higher-frequency neighbour in an emotional orthographic Stroop paradigm. Stimuli were coloured neutral words that had either (1) no orthographic neighbour (e.g. PISTIL [pistil]), (2) one neutral higher-frequency neighbour (e.g. tirade [tirade]/TIRAGE [draw]) or (3) one negative higher-frequency neighbour (e.g. idiome [idiom]/IDIOTE [idiotic]). The results showed that colour categorization times were longer for words with no orthographic neighbour than for words with one neutral neighbour of higher frequency and even longer when the higher-frequency neighbour was neutral rather than negative. Thus, it appears not only that the orthographic neighbourhood of the coloured stimulus words intervenes in a colour categorization task, but also that the emotional content of the neighbour contributes to response times. These findings are discussed in terms of lexical competition between the stimulus word and non-presented orthographic neighbours, which in turn would modify the strength of reading interference on colour categorization times.

Functional activation during the Stroop is associated with recent alcohol but not marijuana use among high-risk youth

Despite studies showing the relevance of different decision-making abilities, including response inhibition, to likelihood of using substances during adolescence, few have examined these neural processes among high-risk, substance-using youth. The current study explored associations between alcohol and marijuana use and functional activation differences during Stroop performance among a large sample (N=80) of ethnically-diverse, high-risk youth in an fMRI-based task. In the absence of associations between substance use and task behavioral performance, adolescents with greater alcohol use showed less activation during the more cognitively difficult portion of the task across clusters in bilateral cuneus and precuneus, and right and left superior temporal gyrus. No associations were observed with marijuana use. The current results may suggest neural patterns of deactivation in regions important for cognitive control, such that alcohol use may confer additional risk for future decreased inhibition among these high-risk adolescents. The ability to inhibit prepotent responses has been shown to predict later response to treatment, and early interventions to encourage further development of cognitive control could represent promising options for treatment.

Amygdala responses to salient social cues vary with oxytocin receptor genotype in youth

Depression, anxiety, and posttraumatic stress disorder are linked to altered limbic morphology, dysregulated neuroendocrine function, and heightened amygdala responses to salient social cues. Oxytocin appears to be a potent modulator of amygdala reactivity and neuroendocrine responses to psychosocial stress. Given these stress regulatory effects, there is increasing interest in understanding the role of oxytocin in vulnerability to stress-related clinical disorders. The present study examines the impact of a common functional variant within the oxytocin receptor (OXTR) gene (rs2254298) on structure and function of the amygdala in a high-risk sample of urban, low-income, minority youth with a high incidence of early life stress (ELS). Compared to G/G homozygotes, youth carrying the OXTR A-allele showed increased amygdala volume, reduced behavioral performance, and heightened amygdala response during two functional magnetic resonance imaging (fMRI) tasks that involved viewing socially-relevant face stimuli. Higher amygdala response was related to ELS in A-allele carriers but not G/G homozygotes. These findings underscore a series of relations among a common oxytocin system gene variant, ELS exposure, and structure and function of the amygdala in early life. Heightened amygdala response to salient social cues in OXTR A-allele carriers may elevate risk for emotional psychopathology by increasing amygdala involvement in disambiguating environmental cues, particularly for individuals with ELS.

Impact of short-term meditation and expectation on executive brain functions

Meditation improves executive functions such as attention and working memory processes. However, it remains unclear to what extent contextual effects contribute to these improvements, since the role of meditation-associated expectations has not been investigated so far. In a randomized, single-blind, deceptive, between-subject design we compared the impact of short-term meditation (MG) on executive functioning with an expectation (ECG) and a passive control group (CG) as well as the effect of positive and negative outcome expectations. Fifty-nine healthy meditation-naïve volunteers participated on three consecutive days (20 min/session). Five groups were examined: 2 MGs, 2 ECGs and 1 CG. While one MG and one ECG were given positive suggestions concerning the effect of meditation on attention, the other two groups were given negative suggestions. MGs practised a focused attention meditation technique; ECGs were told that they were practising meditation but were given instructions for a sham meditation. CG participants sat in silence with their eyes closed. Interference control (Stroop task), selective sustained attention (d2 task), figural and verbal fluency measures of executive functions were assessed. Results indicate that suggestions have a substantial impact on interference control and verbal fluency, with positive suggestions leading to an increase in performance, whereas negative suggestions impeded improvement. This proof of concept study demonstrates the importance of the implementation of a credible ECG to elucidate context effects in meditation processes. It also indicates that suggestions can modulate the small effect of meditation on verbal fluency.

The relationship between top-down attentional control and changes in weight

AIM

To investigate the relationship between top-down attentional control in the presence of food cues and weight change over a 3-month period.

METHOD

A Stroop task adapted to include background images of high-fat food and neutral items was completed by participants (N=60). Top-down attentional control was assessed by adaptation effects (Stroop effect is smaller when the previous trial is incongruent). To assess weight change, measurements were taken immediately after the Stroop task (T1) and again 3-months later (T2). Differences in weight between T1 and T2 were calculated and three groups formed: weight gain (n=20); weight loss (n=20); and no change in weight (n=20).

RESULTS

Differences in top-down attentional control were observed according to weight change. Participants who demonstrated reduced top-down attentional control also exhibited changes in weight (both loss and gain) over the 3-months. In contrast, the weight of participants who maintained top-down attentional control in the Stroop task remained stable.

CONCLUSIONS

Findings suggest that attentional control may have a role to play in actual eating behavior. Individuals who demonstrated reduced levels across of top-down attentional control also experienced changes in their weight over the 3-month period. Whether individuals lost or gained weight attentional control was reduced. This reduction was, however, not specific to high-fat food cues, but a general reduction in attentional control across both image conditions.

The time course of the aversive conflict signal

The idea that conflicts are aversive signals recently has gained strong support by both physiological as well as psychological evidence. However, the time course of the aversive signal has not been subject to direct investigation. In the present study, participants had to judge the valence of neutral German words after being primed with conflict or non-conflict Stroop stimuli in three experiments with varying SOA (200 ms, 400 ms, 800 ms) and varying prime presentation time. Conflict priming effects (i.e., increased frequencies of negative judgments after conflict as compared to non-conflict primes) were found for SOAs of 200 ms and 400 ms, but absent (or even reversed) with a SOA of 800 ms. These results imply that the aversiveness of conflicts is evaluated automatically with short SOAs, but is actively counteracted with prolonged prime presentation.

Beliefs in being unlucky and deficits in executive functioning: an ERP study

There has been initial evidence to support the Dysexecutive Luck hypothesis, which proposes that beliefs in being unlucky are associated with deficits in executive functioning (Maltby et al., 2013). The present study tested the Dysexecutive Luck hypothesis by examining whether deficits in the early stage of top down attentional control led to an increase of neural activity in later stages of response related selection process among those who thought themselves to be unlucky. Individuals with these beliefs were compared to a control group using an Event-Related Potential (ERP) measure assessing underlying neural activity of semantic inhibition while completing a Stroop test. Results showed stronger main interference effects in the former group, via greater reaction times and a more negative distributed scalp late ERP component during incongruent trials in the time window of 450–780 ms post stimulus onset. Further, less efficient maintenance of task set among the former group was associated with greater late ERP response-related activation to compensate for the lack of top-down attentional control. These findings provide electrophysiological evidence to support the Dysexecutive Luck hypothesis.

Cognitive control and schizophrenia: The greatest reliability of the Stroop task

Three components of cognitive inhibition were compared in patients with schizophrenia and healthy controls. Nineteen patients with schizophrenia were compared to 30 healthy controls, matched for age, sex, and educational level. Cognitive inhibition was examined by (i) access to relevant information (Reading with distraction task), (ii) suppression of no longer relevant information (Trail Making Test B), and (iii) restraint of cognitive resources to relevant information (Stroop Test, Hayling Sentence Completion Test, Go/No-Go Test). Beck Depression Inventory, and Positive and Negative Syndrome Scale were also used. Compared to healthy controls, patients with schizophrenia and stabilized for at least 6 months were slower in the inhibition condition at the Stroop task, read more distractors at the RWD, and made more perseverative errors at the TMT, even after controlling for age, Mini-Mental State Examination score, information speed processing, and accuracy. This difference remained significant after taking into account the level of depressive symptoms and the severity of psychotic symptoms. In multivariate analyses, only the Stroop interference index explained cognitive inhibition deficit in patients with schizophrenia. The abnormal cognitive inhibition process observed in patients with schizophrenia could therefore concerns the ability to restraint, rather than the access or the suppression processes.

Neurotransmitter changes during interference task in anterior cingulate cortex: evidence from fMRI-guided functional MRS at 3 T

Neural activity as indirectly observed in blood oxygenation level-dependent (BOLD) response is thought to reflect changes in neurotransmitter flux. In this study, we used fMRI-guided functional magnetic resonance spectroscopy (MRS) to measure metabolite/BOLD associations during a cognitive task at 3 T. GABA and glutamate concentration in anterior cingulate cortex (ACC) were determined by means of MRS using the SPECIAL pulse sequence before, during and after the performance of a manual Stroop task. MRS voxel positions were centred around individuals' BOLD activity during Stroop performance. Levels of GABA and glutamate showed inverted U-shape patterns across measurement time points (before, during, and after task), glutamine increased linearly and total creatine did not change. The GABA increase during task performance was associated with ACC BOLD signal changes in both congruent and incongruent Stroop conditions. Using an fMRI-guided MRS approach, an association between induced inhibitory neurotransmitter increase and BOLD changes was observed. The proposed procedure might allow the in vivo investigation of normal and dysfunctional associations between neurotransmitters and BOLD signal crucial for cerebral functioning.

Less than meets the eye: reappraising the clinical relevance of attentional bias in addiction

Recent years have seen an explosion of interest in attentional bias in addiction, particularly its clinical relevance. Specifically, numerous articles claimed to demonstrate either that (1) attentional bias measured in treatment settings could predict subsequent relapse to substance use, or (2) direct modification of attentional bias reduced substance use and improved treatment outcomes. In this paper, we critically evaluate empirical studies that investigated these issues. We show that the evidence regarding both of these claims is decidedly mixed, and that many of the studies that appear to yield positive findings have serious methodological and statistical limitations. We contend that the available literature suggests that attentional bias for drug cues fluctuates within individuals because it is an output of the underlying motivational state at that moment in time, but there is no convincing evidence that it exerts a causal influence on substance use. Future research should make use of experience sampling methodology to characterise the clinical significance of fluctuations in attentional bias over time.

Reaction time variability and related brain activity in methamphetamine psychosis

BACKGROUND

This study investigated the dynamics of cognitive control instability in methamphetamine (MA) abuse, as well its relationship to substance-induced psychiatric symptoms and drug use patterns.

METHODS

We used an ex-Gaussian reaction time (RT) distribution to examine intraindividual variability (IIV) and excessively long RTs (tau) in an individual's RT on a Stroop task in 30 currently drug-abstinent (3 months to 2 years) MA abusers compared with 27 nonsubstance-abusing control subjects. All subjects underwent functional magnetic resonance imaging while performing the Stroop task, which allowed us to measure the relationship between IIV and tau to functional brain activity.

RESULTS

Elevated IIV in the MA compared with the control group did not reach significance; however, when the MA group was divided into those subjects who had experienced MA-induced psychosis (MAP+) (n = 19) and those who had not (n = 11), the MAP+ group had higher average IIV compared with the other groups (p < .03). In addition, although control subjects displayed a relationship between IIV and conflict-related brain activity in bilateral prefrontal cortex such that increased IIV was associated with increased activity, the MAP+ group displayed this relationship in right prefrontal cortex only, perhaps reflecting elevated vigilance in the MAP+ group. Greater IIV did not correlate with severity of use or months MA abstinent. No group differences emerged in tau values.

CONCLUSIONS

These results suggest increased cognitive instability in those MA-dependent subjects who had experienced MA-induced psychosis.

Cognitive inhibition in older high-lethality suicide attempters

BACKGROUND

People who attempt suicide often display cognitive impairments, particularly poor cognitive control. Could poor cognitive control contribute to high suicide rates in old age? A component of cognitive control, cognitive inhibition-active suppression of task-irrelevant processing-is very sensitive to aging and has been linked to attempted suicide. We investigated cognitive inhibition in older high-lethality suicide attempters, closely resembling suicide victims, as well as low-lethality attempters, and control groups with and without depression and suicidal ideation.

METHODS

A total of 102 participants aged 60 years and older (17 psychiatrically healthy control subjects, 38 depressed control subjects, 16 suicide ideators, 14 low-lethality suicide attempters, and 17 high-lethality suicide attempters) underwent comprehensive clinical and cognitive assessments. They completed the Delis-Kaplan Executive Function System Color-Word Interference Test, a validated modification of the Stroop test.

RESULTS

High-lethality suicide attempters demonstrated a distinct pattern of cognitive inhibition deficits. Compared with psychiatrically healthy control subjects and suicide ideators, high-lethality attempters took longer to complete inhibition trials, even after accounting for potential confounding factors (age, education, Mini mental state examination score, information processing speed, and accuracy). Compared with non-suicidal depressed and healthy control subjects, low-lethality suicide attempters committed more uncorrected errors; however, this difference was not specific to the inhibition condition.

CONCLUSIONS

Older suicide attempters are a cognitively heterogeneous group. Poor cognitive control in high-lethality attempters may undermine their ability to solve real-life problems, precipitating a catastrophic accumulation of stressors. Meanwhile, low-lethality attempters' poor performance may reflect a careless approach to the task or faulty monitoring.

A translational investigation targeting stress-reactivity and prefrontal cognitive control with guanfacine for smoking cessation

Stress and prefrontal cognitive dysfunction have key roles in driving smoking; however, there are no therapeutics for smoking cessation that attenuate the effects of stress on smoking and enhance cognition. Central noradrenergic pathways are involved in stress-induced reinstatement to nicotine and in the prefrontal executive control of adaptive behaviors. We used a novel translational approach employing a validated laboratory analogue of stress-precipitated smoking, functional magnetic resonance imaging (fMRI), and a proof-of-concept treatment period to evaluate whether the noradrenergic α2a agonist guanfacine (3 mg/day) versus placebo (0 mg/day) reduced stress-precipitated smoking in the laboratory, altered cortico-striatal activation during the Stroop cognitive-control task, and reduced smoking following a quit attempt. In nicotine-deprived smokers (n=33), stress versus a neutral condition significantly decreased the latency to smoke, and increased tobacco craving, ad-libitum smoking, and systolic blood pressure in placebo-treated subjects, and these effects were absent or reduced in guanfacine-treated subjects. Following stress, placebo-treated subjects demonstrated decreased cortisol levels whereas guanfacine-treated subjects demonstrated increased levels. Guanfacine, compared with placebo, altered prefrontal activity during a cognitive-control task, and reduced cigarette use but did not increase complete abstinence during treatment. These preliminary laboratory, neuroimaging, and clinical outcome data were consistent and complementary and support further development of guanfacine for smoking cessation.

Attention and control of manual responses in cognitive conflict: Findings from TMS perturbation studies

The article reviews studies that have used the perturbation approach of Transcranial Magnetic Stimulation (TMS) to assess the control of attention and manual response selection in conflict situations as elicited in three established paradigms: the Simon paradigm, the Flanker paradigm, and the Stroop paradigm. After describing the experimental conflict paradigms and briefly introducing TMS we review evidence for the involvement of different frontal and parietal cortical regions in the control of attention and response selection. For example, areas such as the frontal eye field (FEF) appear to significantly contribute to the encoding of spatial attributes of stimuli and areas of the parietal cortex, such as angular gyrus (AG), mediate the allocation of spatial attention and orienting. The dorsal medial frontal cortex (dMFC), supramarginal gyrus (SMG) and pre-supplementary motor area (pre-SMA) appear to be more related to response-related aspects of the conflicts (i.e., enhancement of signals related to correct movements, transformation of spatial information action codes, resolution of response selection conflicts, respectively). The reviewed studies illustrate crucial benefits but also limitations of TMS as well as the value of the combination of TMS with other methods. We suggest topics and approaches for future studies.

Cognitive control network function in alcohol use disorder before and during treatment with lorazepam

Individuals with alcohol use disorders (AUDs) have deficits in cognitive control, but how they change with treatment is unclear. Seven patients with AUD and anxiety from an open-label trial of disulfiram plus lorazepam performed a multisensory Stroop task during fMRI (both pre and post initiation of treatment), and were compared to nine healthy controls (HCs) (n = 16; Albuquerque, NM; years 2009-2012). Evoked BOLD signal and resting state functional connectivity were compared (HC vs. AUD; Scan 1 vs. Scan 2). AUD demonstrated hyperactivity and altered connectivity in the cognitive control network compared to HC, but treatment did not normalize function.

Stroop interference in adults with dyslexia

Prior research on developmental dyslexia using Stroop tasks with young participants has found increased interference in participants with dyslexia relative to controls. Here we extend these findings to adult participants, and introduce a novel test of Stroop incongruity, whereby the color names appeared on an object colored in the incongruent color. The results imply that impaired inhibitory and executive attentional mechanisms are still deficient in adults with dyslexia and that other forms of attentional mechanisms, such as object-based attention, might also be impaired in dyslexia. Dyslexia arises not only from deficits in phonological processing, but from attentional mechanisms as well.

Culture modulates the brain response to human expressions of emotion: electrophysiological evidence

To understand how culture modulates on-line neural responses to social information, this study compared how individuals from two distinct cultural groups, English-speaking North Americans and Chinese, process emotional meanings of multi-sensory stimuli as indexed by both behaviour (accuracy) and event-related potential (N400) measures. In an emotional Stroop-like task, participants were presented face-voice pairs expressing congruent or incongruent emotions in conditions where they judged the emotion of one modality while ignoring the other (face or voice focus task). Results indicated that while both groups were sensitive to emotional differences between channels (with lower accuracy and higher N400 amplitudes for incongruent face-voice pairs), there were marked group differences in how intruding facial or vocal cues affected accuracy and N400 amplitudes, with English participants showing greater interference from irrelevant faces than Chinese. Our data illuminate distinct biases in how adults from East Asian versus Western cultures process socio-emotional cues, supplying new evidence that cultural learning modulates not only behaviour, but the neurocognitive response to different features of multi-channel emotion expressions.

A signal detection analysis of executive control performance among adolescent inhalant and cannabis users

BACKGROUND

Inhalant users have multiple comorbid issues (e.g., polydrug use) that complicate identifying inhalant-specific cognitive deficits.

OBJECTIVES

The aim of the present study was to use signal detection theory to identify inhalant-specific differences in executive control.

METHODS

We examined three well-matched groups: 19 inhalant users, 19 cannabis users, and 19 controls using Stroop and Go/No-Go tasks.

RESULTS

Inhalant users demonstrated significantly lower d-prime scores relative to controls, but not cannabis users, on both tasks, suggesting possible executive deficits relative to controls. CONCLUSIONS/IMPORTANCE: The results of this study raise questions regarding inhalant toxicity and the vulnerability of the adolescent brain to drugs of abuse.

Three key regions for supervisory attentional control: evidence from neuroimaging meta-analyses

The supervisory attentional system has been proposed to mediate non-routine, goal-oriented behaviour by guiding the selection and maintenance of the goal-relevant task schema. Here, we aimed to delineate the brain regions that mediate these high-level control processes via neuroimaging meta-analysis. In particular, we investigated the core neural correlates of a wide range of tasks requiring supervisory control for the suppression of a routine action in favour of another, non-routine one. Our sample comprised n=173 experiments employing go/no-go, stop-signal, Stroop or spatial interference tasks. Consistent convergence across all four paradigm classes was restricted to right anterior insula and inferior frontal junction, with anterior midcingulate cortex and pre-supplementary motor area being consistently involved in all but the go/no-go task. Taken together with lesion studies in patients, our findings suggest that the controlled activation and maintenance of adequate task schemata relies, across paradigms, on a right-dominant midcingulo-insular-inferior frontal core network. This also implies that the role of other prefrontal and parietal regions may be less domain-general than previously thought.

Hemodynamic monitoring of middle cerebral arteries during cognitive tasks performance

AIM

The aim of this study was to obtain temporal pattern and hemispheric dominance of blood flow velocity (BFV) changes and to assess suitability of different cognitive tasks for monitoring of BFV changes in the middle cerebral arteries (MCA).

METHODS

BFV were recorded simultaneously in MCA during performance of phonemic verbal fluency test (pVFT), Trail Making Tests A and B (TMTA and TMTB) and Stroop tests in 14 healthy, right-handed volunteers aged 20-26 years.

RESULTS

A significant increase of BFV in both MCA was obtained during performance of all cognitive tasks. Statistically significant lateralization was found during performance of Stroop test with incongruent stimuli, while TMTB was found to have the best activation potential for MCA.

CONCLUSION

Our findings specify TMTB as the most suitable cognitive test for monitoring of BFV in MCA.