Maren Boecker

Prefrontal brain activation during stop-signal response inhibition: An event-related functional near-infrared spectroscopy study

Previous lesion and neuroimaging studies have shown that the frontal lobes play an important role in response inhibition. In the present study event-related functional near-infrared spectroscopy (NIRS) was applied to investigate cerebral blood oxygenation in the right and left prefrontal cortex (PFC) in 15 male participants during the performance of a stop-change paradigm. Data analysis showed stronger brain activation in the left and right PFC during successful and failed stopping of initiated responses in comparison to a condition without stopping. Changes in cerebral blood oxygenation were more pronounced in the right than in the left PFC. No substantial activation changes were found during successful or failed changing of initiated responses (response inhibition and subsequent response re-engagement). The findings indicate that NIRS is suitable for the functional identification of prefrontal activation during the inhibition of initiated responses and provide further support for the contribution of the PFC to response inhibition.

Development and validation of the Rasch-based depression screening (DESC) using Rasch analysis and structural equation modelling

Questionnaires for the assessment of depression benefit from modern test construction like item-response-modelling. We developed two parallel 10 item depression questionnaires, the Rasch-based Depression Screening version 1 (DESC-I) and 2 (DESC-II), by combining Rasch analysis and structural equation modelling on patient samples suffering primarily from a mental disorder or from somatic diseases. Both scales base upon a Rasch homogeneous item bank and proved unidimensionality and good model fit. Cut-off scores with good sensitivity and specificity were developed using ROC analyses. Results suggest that DESC may be appropriately used to screen for depression and may be beneficial for repeated measurements.

When response inhibition is followed by response reengagement: An event-related fMRI study

In the course of daily living, changing environmental demands often make our actions, once initiated, unnecessary or even inappropriate. Under such circumstances, the ability to inhibit the obsolete action and to update behavior can be of vital importance. Previous lesion and neuroimaging studies have shown that the right prefrontal cortex and the basal ganglia seem to play an important role in the inhibition of already initiated motor responses. The present study was designed to investigate whether the neural activity of inhibitory motor control was altered if the inhibition process was succeeded by an additional process, namely the reengagement into an alternative action. Therefore, cerebral blood oxygenation during performance of a stop‐change paradigm was registered in 15 male participants using event‐related functional magnetic resonance imaging. Data analysis showed, that during successful and failed stopping and changing (response inhibition and subsequent response reengagement) of initiated motor responses a very similar network was activated including primarily the right inferior frontal cortex (IFC). Besides, stopping‐related activation in right IFC was significantly greater for fast inhibitors than for slow ones. Results of the present study thus further underline the important role of right IFC in response inhibition and suggest that the inhibition process functions similarly regardless whether changing task demands require the complete suppression of an already initiated motor response or its suppression and a subsequent response reengagement into an alternative action. Hum Brain Mapp, 2010.

Stop or stop-change — Does it make any difference for the inhibition process?

In the course of daily living altering environmental conditions or changing internal states often cause us to abandon obsolete planned or initiated actions and force us to update our behavior. The stop-change paradigm, an extension of the very popular stop-signal paradigm, allows the investigation of response inhibition and response re-engagement in a laboratory setting. This is very important as everyday life rarely calls for the complete suppression of actions without subsequent behavioral adjustment. The present review first gives a short overview on stop-signal inhibition and its behavioral and neural models before summarizing the findings in the stop-change domain. In doing so, this review shall contribute to a better understanding of the functional and neural architecture of response inhibition and re-engagement. Moreover, the question is raised whether the same or different inhibition process(es) are involved in stop-signal- and stop-change inhibition.

Serotonergic modulation of response inhibition and re‐engagement? Results of a study in healthy human volunteers

Cognitive functions dependent on the prefrontal cortex, such as the ability to suppress behavior (response inhibition) and initiate a new one (response re‐engagement) is important in the activities of daily life. Central serotonin (5‐HT) function is thought to be a critical component of these cognitive functions. In recent studies, 5‐HT failed to affect stop‐signal reaction time (SSRT), a fundamental process in behavioral inhibition. We were interested if response inhibition and re‐engagement are influenced through central 5‐HT activity as mediated via the 5‐HT transporter.

The role of 5-HT in response inhibition and re-engagement

In animal and human research, the neurotransmitter serotonin (5-HT) has been implicated in inhibitory control. Using functional magnetic resonance imaging (fMRI), the present study investigated the acute effects of pharmacological modulation of the serotonergic system on brain activation during response inhibition and re-engagement in healthy human volunteers. In a randomized double-blind placebo-controlled cross-over design 14 men received either a single oral dose of the selective serotonin reuptake inhibitor (SSRI) escitalopram (10mg) or a placebo. At the time of the expected plasma peak concentration, participants performed a stop-change task during fMRI. Escitalopram did not affect behavioural performance, since the main effect did not reveal significant differences between reaction times of go-, stop- or change-trials. During successful response inhibition, escitalopram, however, was associated with enhanced brain activation in right prefrontal cortex, right supplementary/pre-motor and bilateral cingulate cortex, and subcortical regions. During inhibition failures, escitalopram also modulated a broad network of brain regions, including anterior cingulate, right parietal cortex, right orbitofrontal cortex, and areas in right temporal cortex and subcortical regions. During response re-engagement escitalopram increased brain activation in right inferior frontal gyrus and precuneus as well as in left middle temporal gyrus. The results implicate the involvement of 5-HT in neural regulation of response inhibition and re-engagement. This study also provides evidence that 5-HT affects both action restraint and action cancellation through modulation of activation of brain areas. The results support the view for a fronto-striatal circuitry for response inhibition in conjunction with serotonin.

Influence of cue exposure on inhibitory control and brain activation in patients with alcohol dependence.

Alcohol dependence is a serious condition characterized by persistent desires to drink and unsuccessful efforts to control alcohol consumption despite the knowledge of dysfunction through the usage. The study at hand examined the influence of an alcohol exposure on inhibitory processes. Research provides evidence that trying to resist the temptation to drink exerts self-control, a limited resource which is used during all acts of inhibition. In line with this, studies demonstrate an impaired ability to regulate an already initiated response in alcohol-dependent and healthy subjects when confronted with alcohol-related stimuli. The related neuronal correlates in alcohol-dependent patients remain to be elucidated. The inhibition performance of 11 male alcohol-dependent patients during an alcohol exposure was compared with the task performance during a control condition. Behavioral data and neural brain activation during task performance were acquired by means of functional magnetic resonance imaging. The alcohol cue exposure led to subjectively stronger urges to drink which was accompanied by differential neural activation in amygdala and hippocampus. Moreover, the results revealed typical neural activation during inhibition performance across both conditions. Anyhow, we could not detect any behavioral deficits and only subtle neural differences between induction conditions during the performance of the inhibition task within the inferior frontal cortex. The results suggest that although the sample reports a subjectively stronger urge to drink after the alcohol cue exposure this effect was not strong enough to significantly impair task performance. Coherently, we discover only subtle differential brain activation between conditions during the inhibition task. In opposition to findings in literature our data do not reveal that an exposure to alcohol-related cues and thereby elicited cue reactivity results in impaired inhibition abilities.

Adaptive screening for depression--recalibration of an item bank for the assessment of depression in persons with mental and somatic diseases and evaluation in a simulated computer-adaptive test environment.

OBJECTIVE This study conducted a simulation study for computer-adaptive testing based on the Aachen Depression Item Bank (ADIB), which was developed for the assessment of depression in persons with somatic diseases. Prior to computer-adaptive test simulation, the ADIB was newly calibrated. METHODS Recalibration was performed in a sample of 161 patients treated for a depressive syndrome, 103 patients from cardiology, and 103 patients from otorhinolaryngology (mean age 44.1, SD=14.0; 44.7% female) and was cross-validated in a sample of 117 patients undergoing rehabilitation for cardiac diseases (mean age 58.4, SD=10.5; 24.8% women). Unidimensionality of the itembank was checked and a Rasch analysis was performed that evaluated local dependency (LD), differential item functioning (DIF), item fit and reliability. CAT-simulation was conducted with the total sample and additional simulated data. RESULTS Recalibration resulted in a strictly unidimensional item bank with 36 items, showing good Rasch model fit (item fit residuals<|2.5|) and no DIF or LD. CAT simulation revealed that 13 items on average were necessary to estimate depression in the range of -2 and +2 logits when terminating at SE≤0.32 and 4 items if using SE≤0.50. Receiver Operating Characteristics analysis showed that θ estimates based on the CAT algorithm have good criterion validity with regard to depression diagnoses (Area Under the Curve≥.78 for all cut-off criteria). CONCLUSION The recalibration of the ADIB succeeded and the simulation studies conducted suggest that it has good screening performance in the samples investigated and that it may reasonably add to the improvement of depression assessment.

The Positive Illusory Bias in Children and Adolescents With ADHD: Further Evidence

Objective: This study aimed to examine the accuracy of self-reports of children and adolescents with ADHD in evaluating activity limitations. Method: Self-reports of children/adolescents with ADHD (n = 89) were compared with those of nonreferred children (n = 94), relative to parent reports about children’s competence. Competence was measured with a 34-item rating scale. Behavioral disorders were documented with the Child Behavior Checklist. Results: Children/adolescents with ADHD were much more likely than controls to overestimate their competence in certain daily activities relative to parent reports, demonstrating a positive illusory bias. Positive illusory bias was found to be pronounced in activities, which were expected to be affected by symptoms of ADHD. Overestimations of competencies were more likely to be accompanied with externalizing problems. Conclusion: Results support the presence of the positive illusory bias also in the domain of everyday life activities. Improvement of self-evaluation of competencies should become a focus of treatment.

Can executive control be influenced by performance feedback? Two experimental studies with younger and older adults

Executive control describes a wide range of cognitive processes which are critical for the goal-directed regulation of stimulus processing and action regulation. Previous studies have shown that executive control performance declines with age but yet, it is still not clear whether different internal and external factors—as performance feedback and age—influence these cognitive processes and how they might interact with each other. Therefore, we investigated feedback effects in the flanker task in young as well as in older adults in two experiments. Performance feedback significantly improved executive performance in younger adults at the expense of errors. In older adults, feedback also led to higher error rates, but had no significant effect on executive performance which might be due to stronger interference. Results indicate that executive functions can be positively influenced by performance feedback in younger adults, but not necessarily in older adults.