Model-based and model-free decisions in alcohol dependence

BACKGROUND

Human and animal work suggests a shift from goal-directed to habitual decision-making in addiction. However, the evidence for this in human alcohol dependence is as yet inconclusive.

METHODS

Twenty-six healthy controls and 26 recently detoxified alcohol-dependent patients underwent behavioral testing with a 2-step task designed to disentangle goal-directed and habitual response patterns.

RESULTS

Alcohol-dependent patients showed less evidence of goal-directed choices than healthy controls, particularly after losses. There was no difference in the strength of the habitual component. The group differences did not survive controlling for performance on the Digit Symbol Substitution Task.

CONCLUSION

Chronic alcohol use appears to selectively impair goal-directed function, rather than promoting habitual responding. It appears to do so particularly after nonrewards, and this may be mediated by the effects of alcohol on more general cognitive functions subserved by the prefrontal cortex.

Pavlovian-to-instrumental transfer in alcohol dependence: a pilot study

BACKGROUND

Pavlovian processes are thought to play an important role in the development, maintenance and relapse of alcohol dependence, possibly by influencing and usurping ongoing thought and behavior. The influence of pavlovian stimuli on ongoing behavior is paradigmatically measured by pavlovian-to-instrumental transfer (PIT) tasks. These involve multiple stages and are complex. Whether increased PIT is involved in human alcohol dependence is uncertain. We therefore aimed to establish and validate a modified PIT paradigm that would be robust, consistent and tolerated by healthy controls as well as by patients suffering from alcohol dependence, and to explore whether alcohol dependence is associated with enhanced PIT.

METHODS

Thirty-two recently detoxified alcohol-dependent patients and 32 age- and gender-matched healthy controls performed a PIT task with instrumental go/no-go approach behaviors. The task involved both pavlovian stimuli associated with monetary rewards and losses, and images of drinks.

RESULTS

Both patients and healthy controls showed a robust and temporally stable PIT effect. Strengths of PIT effects to drug-related and monetary conditioned stimuli were highly correlated. Patients more frequently showed a PIT effect, and the effect was stronger in response to aversively conditioned CSs (conditioned suppression), but there was no group difference in response to appetitive CSs.

CONCLUSION

The implementation of PIT has favorably robust properties in chronic alcohol-dependent patients and in healthy controls. It shows internal consistency between monetary and drug-related cues. The findings support an association of alcohol dependence with an increased propensity towards PIT.

Overactive Performance Monitoring as an Endophenotype for Obsessive-Compulsive Disorder: Evidence From a Treatment Study

OBJECTIVE

Overactive performance monitoring, as measured by the error-related negativity in the event-related brain potential, represents one of the most robust psychophysiological alterations in obsessive-compulsive disorder (OCD). It has been proposed as an endophenotype for OCD because it is heritable and more prevalent in families of OCD patients. Consistent with this notion, it is also independent of symptom profile and symptom severity in cross-sectional studies. Longitudinally, it has been shown to be state independent in pediatric patients with OCD. The purpose of the present study was to investigate the state dependency of error monitoring by examining adult OCD patients before and after symptom reduction through cognitive-behavioral therapy (CBT).

METHOD

Error-related and correct-related negativity as electrophysiological indicators of performance monitoring were recorded from 45 OCD patients and 39 healthy comparison subjects while performing a flanker task. Patients were assessed before starting and after completing a standard 30-session CBT, including exposure and response prevention, and healthy comparison subjects were tested after a comparable time interval.

RESULTS

Pretreatment, patients with OCD were characterized by enhanced error-related and correct-related negativity compared with healthy comparison subjects. This difference persisted after treatment when symptoms were substantially reduced. There was no significant correlation between symptom improvement and changes in performance monitoring and no difference in performance monitoring between treatment responders and nonresponders.

CONCLUSIONS

This is the first longitudinal study in adult OCD patients showing stability of enhanced error monitoring following successful symptom reduction through CBT. It supports the hypothesis that overactive performance monitoring is an endophenotype that indicates vulnerability for OCD.

Overactive performance monitoring in obsessive-compulsive disorder is independent of symptom expression

Overactive performance monitoring has been consistently reported in obsessive-compulsive disorder (OCD). OCD is a clinically heterogeneous disorder and is characterized by several symptom dimensions that may have partially distinct neural correlates. We examined whether performance-monitoring alterations are related to symptom severity and symptom dimensions. Electrocortical correlates of performance monitoring were assessed in 72 OCD patients and 72 matched healthy comparison participants during a flanker task. Amplitudes of the error- and correct-related negativity as well as delta and theta power were used to quantify performance-monitoring activity, and a composite measure was derived using factor analysis. Symptom dimension scores were obtained from the Yale-Brown Obsessive Compulsive Scale symptom checklist. OCD patients showed increased electrocortical responses associated with correct and erroneous responses compared to healthy comparison participants. In patients, no correlations were obtained between performance monitoring and global symptom severity as well as lifetime symptom dimension scores. Only a statistical trend was found that higher symmetry/hoarding scores were associated with reduced performance-monitoring activity. For present symptom dimensions scores, an association with rituals/superstitious symptoms was obtained such that higher scores were associated with greater performance-monitoring activity. However, for both dimensions, subjects with low scores or high scores on each dimension were characterized by overactive performance monitoring compared to healthy controls. Overactive brain processes during performance monitoring are a neural correlate of OCD that is independent of global symptom severity and can be observed for all symptom dimensions. This supports the notion of overactive performance monitoring being a candidate endophenotype for OCD.

TMS over the right precuneus reduces the bilateral field advantage in visual short term memory capacity

BACKGROUND

Several studies have demonstrated a bilateral field advantage (BFA) in early visual attentional processing, that is, enhanced visual processing when stimuli are spread across both visual hemifields. The results are reminiscent of a hemispheric resource model of parallel visual attentional processing, suggesting more attentional resources on an early level of visual processing for bilateral displays [e.g. Sereno AB, Kosslyn SM. Discrimination within and between hemifields: a new constraint on theories of attention. Neuropsychologia 1991;29(7):659-75.]. Several studies have shown that the BFA extends beyond early stages of visual attentional processing, demonstrating that visual short term memory (VSTM) capacity is higher when stimuli are distributed bilaterally rather than unilaterally.

OBJECTIVE/HYPOTHESIS

Here we examine whether hemisphere-specific resources are also evident on later stages of visual attentional processing.

METHODS

Based on the Theory of Visual Attention (TVA) [Bundesen C. A theory of visual attention. Psychol Rev 1990;97(4):523-47.] we used a whole report paradigm that allows investigating visual attention capacity variability in unilateral and bilateral displays during navigated repetitive transcranial magnetic stimulation (rTMS) of the precuneus region.

RESULTS

A robust BFA in VSTM storage capacity was apparent after rTMS over the left precuneus and in the control condition without rTMS. In contrast, the BFA diminished with rTMS over the right precuneus.

CONCLUSION

This finding indicates that the right precuneus plays a causal role in VSTM capacity, particularly in bilateral visual displays.

Default mode network subsystem alterations in obsessive-compulsive disorder

BACKGROUND

Although neurobiological models of obsessive-compulsive disorder (OCD) traditionally emphasise the central role of corticostriatal brain regions, studies of default mode network integrity have garnered increasing interest, but have produced conflicting results.

AIMS

To resolve these discrepant findings by examining the integrity of default mode network subsystems in OCD.

METHOD

Comparison of seed-based resting-state functional connectivity of 11 default mode network components between 46 patients with OCD and 46 controls using functional magnetic resonance imaging.

RESULTS

Significantly reduced connectivity within the dorsal medial prefrontal cortex self subsystem was identified in the OCD group, and remained significant after controlling for medication status and life-time history of affective disorders. Further, greater connectivity between the self subsystem and salience and attention networks was observed.

CONCLUSIONS

Results indicate that people with OCD show abnormalities in a neural system previously associated with self-referential processing in healthy individuals, and suggest the need for examination of dynamic interactions between this default mode network subsystem and other large-scale networks in this disorder.

Investigating category- and shape-selective neural processing in ventral and dorsal visual stream under interocular suppression

Recent behavioral and neuroimaging studies using continuous flash suppression (CFS) have suggested that action-related processing in the dorsal visual stream might be independent of perceptual awareness, in line with the "vision-for-perception" versus "vision-for-action" distinction of the influential dual-stream theory. It remains controversial if evidence suggesting exclusive dorsal stream processing of tool stimuli under CFS can be explained by their elongated shape alone or by action-relevant category representations in dorsal visual cortex. To approach this question, we investigated category- and shape-selective functional magnetic resonance imaging-blood-oxygen level-dependent responses in both visual streams using images of faces and tools. Multivariate pattern analysis showed enhanced decoding of elongated relative to non-elongated tools, both in the ventral and dorsal visual stream. The second aim of our study was to investigate whether the depth of interocular suppression might differentially affect processing in dorsal and ventral areas. However, parametric modulation of suppression depth by varying the CFS mask contrast did not yield any evidence for differential modulation of category-selective activity. Together, our data provide evidence for shape-selective processing under CFS in both dorsal and ventral stream areas and, therefore, do not support the notion that dorsal "vision-for-action" processing is exclusively preserved under interocular suppression.

The suggestible brain: posthypnotic effects on value-based decision-making

Hypnosis can affect perception, motor function and memory. However, so far no study using neuroimaging has investigated whether hypnosis can influence reward processing and decision-making. Here, we assessed whether posthypnotic suggestions can diminish the attractiveness of unhealthy food and whether this is more effective than diminishing attractiveness by one's own effort via autosuggestion. In total, 16 participants were hypnotized and 16 others were instructed to associate a color cue (blue or green) with disgust regarding specific snacks (sweet or salty). Afterwards, participants bid for snack items shown on an either blue or green background during functional magnetic resonance imaging measurement. Both hypnosis and autosuggestion successfully devalued snacks. This was indicated by participants' decision-making, their self-report and by decreased blood oxygen level-dependent signal in the ventromedial prefrontal cortex (vmPFC), a region known to represent value. Different vmPFC subregions coded for cue and snack type. The cue had significantly stronger effects on vmPFC after hypnosis than after autosuggestion, indicating that hypnosis was more effective in genuinely reducing value. Supporting previous findings, the precuneus was involved in the hypnotic effects by encoding whether a snack was sweet or salty during hypnotic cue presentation. Our results demonstrate that posthypnotic suggestions can influence valuation and decision-making.

Cognitive-behavioral therapy as continuation treatment to sustain response after electroconvulsive therapy in depression: a randomized controlled trial

BACKGROUND

Although electroconvulsive therapy (ECT) is the most effective acute antidepressant intervention, sustained response rates are low. It has never been systematically assessed whether psychotherapy, continuation ECT, or antidepressant medication is the most efficacious intervention to maintain initial treatment response.

METHODS

In a prospective, randomized clinical trial, 90 inpatients with major depressive disorder (MDD) were treated with right unilateral ultra-brief acute ECT. Electroconvulsive therapy responders received 6 months guideline-based antidepressant medication (MED) and were randomly assigned to add-on therapy with cognitive-behavioral group therapy (CBT-arm), add-on therapy with ultra-brief pulse continuation electroconvulsive therapy (ECT-arm), or no add-on therapy (MED-arm). After the 6 months of continuation treatment, patients were followed-up for another 6 months. The primary outcome parameter was the proportion of patients who remained well after 12 months.

RESULTS

Of 90 MDD patients starting the acute phase, 70% responded and 47% remitted to acute ECT. After 6 months of continuation treatment, significant differences were observed in the three treatment arms with sustained response rates of 77% in the CBT-arm, 40% in the ECT-arm, and 44% in the MED-arm. After 12 months, these differences remained stable with sustained response rates of 65% in the CBT-arm, 28% in the ECT-arm, and 33% in the MED-arm.

CONCLUSIONS

These results suggest that ultra-brief pulse ECT as a continuation treatment correlates with low sustained response rates. However, the main finding implicates cognitive-behavioral group therapy in combination with antidepressants might be an effective continuation treatment to sustain response after successful ECT in MDD patients.

Seeing "changes" that aren't there: facial and object discrimination in body dysmorphic disorder

Cognitive-behavioral models of body dysmorphic disorder (BDD) suggest the disorder is characterized by several interpretive, attentional, and perceptual biases that contribute to its maintenance or even development. In addition, the role of aesthetic sensitivity has been discussed in BDD. However, previous research examining the ability to identify subtle changes in facial features and geometrical objects has produced mixed results. The purpose of the current study was to further evaluate facial and object discrimination among individuals with BDD (n=35), individuals with a dermatological condition (n=35), and mentally healthy control participants (n=35) using a facial and object discrimination paradigm assessing the sensitivity for changes in symmetry, color, and size. Overall, the groups did not differ with respect to their performance in detecting actual changes in facial or object images. However, there was a significant group difference when they were presented with a series of unchanged facial but not object images: the BDD group rated identical facial images significantly more often as being changed, relative to individuals without BDD. The current results are discussed in light of the existing literature on facial and object discrimination in BDD.

Amygdala hyperactivation during symptom provocation in obsessive-compulsive disorder and its modulation by distraction

Anxiety disorders have been linked to a hyperactivated cortico-amygdalar circuitry. Recent findings highlight the amygdala's role in mediating elevated anxiety in obsessive–compulsive disorder (OCD). However, modulation of amygdala hyperactivation by attentional distraction – an effective emotion regulation strategy in healthy individuals – has not yet been examined. While undergoing functional magnetic resonance imaging twenty-one unmedicated OCD patients and 21 controls performed an evaluation and a distraction task during symptom provocation with individually tailored OCD-relevant pictures. To test the specificity of responses, additional aversive and neutral stimuli were included. Significant group-by-picture type interactions were observed within fronto–striato–limbic circuits including the amygdala. In these regions patients showed increased BOLD responses during processing of OCD triggers relative to healthy controls. Amygdala hyperactivation was present across OCD symptom dimensions indicating that it represents a common neural correlate. During distraction, we observed dampening of patients' amygdala hyperactivity to OCD-relevant stimuli. Augmented amygdala involvement in patients during symptom provocation, present across OCD symptom dimensions, might constitute a correlate of fear expression in OCD linking it to other anxiety disorders. Attentional distraction seemed to dampen emotional processing of disorder-relevant stimuli via amygdala downregulation. The clinical impact of this strategy to manage anxiety in OCD should be further elucidated.

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Investigating modulation of amygdala hyperactivation during OCD symptom provocation

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Increased fronto–striato–limbic activity to symptom triggers in patients vs. controls

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Dampening of amygdala hyperactivity to OCD-relevant stimuli during distraction

Autonomic responses and neural-cardiac coupling during individually tailored symptom provocation in obsessive-compulsive disorder

Elevated anxiety in obsessive-compulsive disorder (OCD) has been linked to cortico-limbic hyperactivation, whereas hyperarousal of the autonomous nerve system (ANS) has inconsistently been found. We investigate ANS functioning during symptom provocation with individually tailored OCD-relevant pictures in 14 unmedicated patients and 14 controls and link it to activation in brain areas involved in ANS regulation. In addition to OCD-triggers, aversive and neutral control stimuli were included. Both groups showed increased skin conductance and heart rate changes to aversive control stimuli, whereas only patients demonstrated augmented skin conductance responses to OCD-triggers. Overall ANS hyperarousal in patients relative to controls was found at trend level. Activity in limbic and paralimbic areas in OCD patients was increased to both generally aversive and OCD-relevant stimuli, whereas dorsolateral prefrontal cortex (DLPFC) hyperactivation, covarying with cardiac responses in patients but not in controls, was present for disorder-relevant triggers only. Despite the small study group, these preliminary findings suggest ANS hyperactivity during OCD symptom provocation that could reflect arousal to the perceived threatening value of OCD-triggers and might mediate elevated anxiety.

Neural correlates of impaired volitional action control in schizophrenia patients

Slowed initiation of volitional but not visually guided saccades indicates impaired volitional action control in schizophrenia patients (SZ). The present study aimed at identifying neural correlates of this specific deficit. Fourteen SZ and 13 healthy control participants (HC) underwent functional magnetic resonance imaging while performing volitional and visually guided saccades. SZ showed increased latencies in volitional but not in visually guided saccades. Brain activation during volitional saccades compared to visually guided saccades was increased in SZ compared to HC in several areas: the supplementary eye fields, suggesting inefficient production of volitional saccades; the prefrontal cortex, pointing to altered top down control on complex eye movements; and the left middle temporal area, suggesting changes in early sensory and attention processing during the volitional control of saccades in SZ.

Timing effects of antecedent- and response-focused emotion regulation strategies

Distraction and cognitive reappraisal influence the emotion-generative process at early stages and have been shown to effectively attenuate emotional responding. Inhibiting emotion-expressive behavior is thought to be less beneficial due to later implementation, but empirical results are mixed. Thus, the current study examined the temporal dynamics of these emotion regulation strategies at attenuating the late positive potential (LPP) while participants were shown unpleasant pictures. Results revealed that all strategies successfully reduced the LPP and self-reported negative affect. We confirmed that distraction attenuated the LPP earlier than cognitive reappraisal. Surprisingly, expressive suppression affected emotional responding as early as distraction. This suggests that suppression was used preventively and disrupted the emotion-generative process from the very beginning instead of targeting the emotional response itself. Thus, the obtained results point to the importance of considering the point in time when response-focused emotion regulation strategies are being implemented.

Abnormally high degree connectivity of the orbitofrontal cortex in obsessive-compulsive disorder

IMPORTANCE

Neurobiological models of obsessive-compulsive disorder (OCD) predict hyperactivity in brain circuits involving the orbitofrontal cortex and the basal ganglia, but it is unclear whether these areas are also characterized by altered brain network properties.

OBJECTIVES

To determine regions of abnormal degree connectivity in patients with OCD and to investigate whether connectivity measures are affected by antidepressant medication in OCD.

DESIGN

Case-control cross-sectional study using resting-state functional magnetic resonance imaging and a data-driven, model-free method to test for alterations in the degree of whole-brain, distant, and local connectivity in unmedicated patients with OCD compared with healthy controls.

SETTING

Outpatient clinic for OCD.

PARTICIPANTS

Twenty-three patients with OCD (12 women, 11 men) receiving no medication, 23 patients with OCD (14 women, 9 men) treated with antidepressant medication, and 2 equally sized control samples matched for age, sex, handedness, educational level, and IQ.

MAIN OUTCOME MEASURES

Statistical parametric maps testing the degree of distant and local functional connectivity of each voxel (hub analysis at voxel level) and OCD symptom severity.

RESULTS

Unmedicated patients with OCD showed greater distant connectivity in the orbitofrontal cortex and subthalamic nucleus and greater local connectivity in the orbitofrontal cortex and the putamen. Furthermore, distant connectivity of the orbitofrontal cortex and the putamen positively correlated with global OCD symptom severity. Medicated patients with OCD showed reduced local connectivity of the ventral striatum compared with the unmedicated patients.

CONCLUSIONS AND RELEVANCE

Consistent with neurobiological models of OCD, the orbitofrontal cortex and the basal ganglia are hyperconnected in unmedicated patients. The finding of distant connectivity alterations of the orbitofrontal cortex and the basal ganglia represents initial evidence of greater connections with distant cortical areas outside of corticostriatal circuitry. Furthermore, these data suggest that antidepressant medication may reduce connectivity within corticobasal ganglia-thalamo-cortical circuits in OCD.