inhibition
Research Papers
Neural mechanisms of persistent avoidance in OCD: A novel avoidance devaluation study
Obsessive-Compulsive Disorder (OCD) is characterized by repetitive avoidance behavior which is distressing and associated with marked impairment of everyday life. Recently, paradigms have been designed to explore the hypothesis that avoidance behavior in OCD is consistent with a formal conception of habit. Such studies have involved a devaluation paradigm, in which the value of a previously rewarded cue is altered so that avoidance is no longer necessary. We employed a rule-based avoidance task which included a devaluation, examining behavioral performance on the task and their neural correlates using functional MRI in groups of participants with OCD (n = 44) and healthy control participants (n = 46). Neuroimaging data were analyzed using a general linear model (GLM), modelling valued, devalued and control cues, as well as feedback events. First, while no overall effect of OCD was seen on devaluation performance, patients with longer illness duration showed poorer devaluation performance (χ2 = 13.84, p < 0.001). Reduced devaluation was related to impaired learning on the overtraining phase of the task, and to enhanced feedback activation in the caudate and parietal lobe during within-scanner retraining (T = 5.52, p_FWE = 0.003), across all participants. Second, a significant interaction effect was observed in the premotor cortex (F = 29.03, p_FWE = 0.007) coupled to the devalued cue. Activations were divergent in participants with OCD (lower activation) and healthy controls (higher activation) who did not change responding to the devalued cue following devaluation, and intermediate in participants who did change responding (T = 5.39, p_FWE = 0.003). Finally, consistent with previous work, medial orbitofrontal cortex activation coupled to valued cues was reduced in OCD compared to controls (T = 3.49, p_FWE = 0.009). The findings are discussed in terms of a prediction error-based model of goal-directed and habitual control: specifically, how goal-directed control might be diminished in OCD in favor of habits. They suggest that illness duration might be significant determinant of variation in impaired goal-directed learning in OCD, and be a factor relevant for understanding discrepancies across studies. Overall, the study shows the potential of conceptual replication attempts to provide complementary insights into compulsive behavior and its associated neural circuitry in OCD.
View Full Paper →Preventing relapse in alcohol disorder with EEG-neurofeedback as a neuromodulation technique: A review and new insights regarding its application
Alcohol Use Disorder (AUD) has a disconcertingly high relapse rate (70–80% within a year following withdrawal). Preventing relapse or minimizing its extent is hence a challenging goal for long-term successful management of AUD. New perspectives that rely on diverse neuromodulation tools have been developed in this regard as care supports. This paper focuses on electroencephalogram-neurofeedback (EEG-NF), which is a tool that has experienced renewed interest in both clinical and research areas. We review the literature on EEG-based neurofeedback studies investigating the efficacy in AUD and including at least 10 neurofeedback training sessions. As neurofeedback is a form of biofeedback in which a measure of brain activity is provided as feedback in real-time to a subject, the high degree of temporal resolution of the EEG interface supports optimal learning. By offering a wide range of brain oscillation targets (alpha, beta, theta, delta, gamma, and SMR) the EEG-NF procedure increases the scope of possible investigations through a multitude of experimental protocols that can be considered to reinforce or inhibit specific forms of EEG activity associated with AUD-related cognitive impairments. The present review provides an overview of the EEG-NF protocols that have been used in AUD and it highlights the current paucity of robust evidence. Within this framework, this review presents the arguments in favor of the application of EEG-NF as an add-on tool in the management of alcohol disorders to enhance the cognitive abilities required to maintain abstinence more specifically, with a focus on inhibition and attentional skills.
View Full Paper →Effects of Neurofeedback Training on Inhibitory Capacities in ADHD Children: A Single-Blind, Randomized, Placebo-Controlled Study
Studies performed during the last decades suggest that neurofeedback (NF) training can effectively reduce symptomatology in children with Attention deficit hyperactivity disorder (ADHD). Yet questions remain concerning specific effects of NF training in ADHD children, because these studies did not use a randomized, placebo-controlled approach. To address this issue, such an approach was used in the present study to measure the impact of NF training on inhibitory capacities. Method. Nine ADHD children (with no comorbidity), aged 8 to 13 years, were randomly assigned to either an experimental group (n1/45) or a placebo group (n1/44). For both groups, training protocols comprised 40 one-hr sessions (20 meetings of 2 sessions each). Sensorimotor rhythm=Theta training was used in the experimental group. Prerecorded sessions of the first author's EEG activity were used in the placebo group. Pre- and posttraining assessments consisted of the Conner's Parent Rating Scales (CPRS-R) and neuropsychological tests. A multiple case study strategy was applied for data analysis using a Reliable Change Index when applicable. Results. One experimental participant was a dropout, and one placebo participant had to be discontinued due to adverse effects. The latter participant accepted to undergo posttraining evaluations; hence an Intention-to-Treat analysis was performed on this participant's data. Remaining participants showed significant improvements on the CPRS-R. Improvements were measured on the Variability measure of the CPT-II consistently across the placebo group and on the Inhibition Condition of the Stroop Task for all but one placebo participant. The same trend was found for the Inhibition=Switching Condition (Stroop Task) across the experimental group (n1/44). Conclusion. The small sample size precludes from evaluating specific neurofeedback effects. Still, the presence of placebo responses suggests that other factors, such as motivation or expectations, might contribute to the outcome of NF training in children with ADHD.
View Full Paper →EEG alpha oscillations: The inhibition–timing hypothesis
The traditional belief is that the event-related alpha response can solely be described in terms of suppression or event-related desynchronization (ERD). Recent research, however, has shown that under certain conditions alpha responds reliably with an increase in amplitudes (event-related synchronization or ERS). ERS is elicited in situations, where subjects withhold or control the execution of a response and is obtained over sites that probably are under, or exert top-down control. Thus, we assume that alpha ERS reflects top-down, inhibitory control processes. This assumption leads over to the timing aspect of our hypothesis. By the very nature of an oscillation, rhythmic amplitude changes reflect rhythmic changes in excitation of a population of neurons. Thus, the time and direction of a change – described by phase – is functionally related to the timing of neuronal activation processes. A variety of findings supports this view and shows, e.g., that alpha phase coherence increases between task-relevant sites and that phase lag lies within a time range that is consistent with neuronal transmission speed. Another implication is that phase reset will be a powerful mechanism for the event-related timing of cortical processes. Empirical evidence suggests that the extent of phase locking is a functionally sensitive measure that is related to cognitive performance. Our general conclusion is that alpha ERS plays an active role for the inhibitory control and timing of cortical processing whereas ERD reflects the gradual release of inhibition associated with the emergence of complex spreading activation processes.
View Full Paper →Passive Infrared Hemoencephalography: Four Years and 100 Migraines
Background. One hundred migraine sufferers were treated using passive Infrared Hemoencephalography (pIR HEG) over a period of four years. All subjects met the criteria for at least one of the categories set forth in the International Headache Society (IHS, 1988) classification criteria for headache disorders for primary migraine. Methods. Subjects were treated using the pIR HEG system in 30-minute sessions. A central forehead placement (approximately Fpz) was used for the sensor assembly for all subjects. Changes in headache patterns were examined. After two years, an infrared video imaging system was added to the data collection process and was available for 61 of the 100 subjects. Infrared forehead images were captured at the start and end of each session to examine changes in prefrontal cortical brain activity. Results. Most of the subjects improved control over their migraine headaches. Over 90% of those subjects who completed at least six sessions reported significant improvements in migraine activity. Conclusions. pIR HEG appears to have a strong impact on migraine headaches, even for people who have not had a positive response to medication. Headache response by the end of six sessions appears to be a good predictor of probability of improvement
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