Inhoudsopgave jaargang 5 (2010) / nummer 1

Instrumentele conditionering van frontaalkwabactiviteit bij gezonde jongvolwassenen

Een dubbelblind placebogecontroleerd onderzoek naar eeg-neurofeedback

HESSEL JAN ENGELBREGT, GILLES KOK, RUUD VIS, DANIEL KEESER, JAN BEREND DEIJEN

Neurofeedbacktraining (nft) is een methode waarvan wordt gedacht dat het hersenactiviteit kan beïnvloeden. Over deze techniek die veelal door psychologen wordt gebruikt, zijn veel publicaties verschenen in wetenschappelijke tijdschriften. Toch heeft nft binnen de psychologische en neurowetenschappelijke gemeenschap een status die in het gunstigste geval marginaal kan worden genoemd. Mogelijk is dit het gevolg van methodologische beperkingen die alle gepubliceerde onderzoeken naar nft kenmerkt.

In dit artikel beschrijven we een dubbelblind, placebogecontroleerd onderzoeksdesign. Dit design hebben we getoetst op praktische haalbaarheid door middel van een studie bij een groep van 25 gezonde studenten. Hierbij kreeg een controlegroep (n = 12) een pseudo-nft. De experimentele groep (n = 10) kreeg nft ter verhoging van frontale beta-activiteit (12-18 Hz) en inhibitie van de frequentieband 35-45 Hz. Dit leidde niet tot een duidelijk verbeterd cognitief presteren, wel tot de verwachte veranderingen in hersenactiviteit tijdens de behandeling. Op basis van deze methodologische toets denken we dat onze aanpak een haalbare oplossing biedt voor de methodologische problemen uit het verleden. nft is daarmee een toetsbaar fenomeen, volgens huidige evidence-based maatstaven.

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This thesis investigated the effect of acute psychological stress and (beta)-adrenergic receptor ((beta)AR) stimulation on the mobilization of CD8+ T lymphocytes (CD8TLs) and progenitor cell (PC) populations. Chapter 2 demonstrated that CD8TL stress- and (beta)AR- sensitivity increases in parallel with greater effector functions and cell differentiation. As Cytomegalovirus (CMV) infection influences CD8TL differentiation, Chapter 3 compared the mobilization of cytotoxic lymphocytes in CMV seropositive and seronegative individuals; CMV infection enhanced the stress reactivity of CD8TLs, CD4TLs and NKT-like cells. Chapter 4 examined whether antigen-specificity could modulate CD8TL stress- and (beta)AR-sensitivity. CMV-specific cells demonstrated enhanced mobilization compared to the total-memory CD8TL and the total Epstein-Barr virus (EBV) population. In Chapter 5, we demonstrated that PC subsets, capable of both replenishing leukocyte populations and maintaining endothelial integrity, were also mobilized by acute psychological stress. This result was not replicated by (beta)ARagonist infusion suggesting the involvement of (alpha)AR or non-adrenergic mechanism. In sum, the current findings suggest that stress mobilization serves to protect the host by increasing immune protection and tissue repair mechanisms. However, such a response may also be detrimental dependent on the circumstance, i.e., infection versus inflammation.

Using virtual reality technology for exposure therapy to treat patients with anxiety disorders is attracting considerable research attention. The ability to monitor patient anxiety level helps therapists to set appropriate anxiety arousing situations. Physiological measure has been put forward as objective indicator of anxiety levels. Because of individual variation, they need a baseline recording which is often conducted in neutral virtual world which does not include phobic stressors. Still because of the novelty of the virtual world, reports in the literature suggest that individuals already show some level of arousal when placed in these worlds. This paper presents two studies which look at the effect two different neutral virtual worlds can have on individuals. Findings suggest that a neutral world does not have to result in an increased level of arousal.

Background
When making decisions, children with oppositional defiant disorder (ODD) are thought to focus on reward and ignore penalty. This is suggested to be associated with a state of low psychophysiological arousal.
Methods
This study investigates decision making in 18 children with oppositional defiant disorder and 24 typically developing control subjects. Children were required to choose between three alternatives that carried either frequent small rewards and occasional small penalties (advantageous), frequent large rewards and increasing penalties (seductive), or frequent small rewards and increasing penalties (disadvantageous). Penalties in the seductive and disadvantageous alternatives increased either in frequency or magnitude in two conditions. Heart rate (HR) and skin conductance responses to reinforcement were obtained.
Results
In the magnitude condition, children with ODD showed an increased preference for the seductive alternative (carrying large rewards); this was not observed in the frequency condition. Children with ODD, compared with typically developing children, displayed greater HR reactivity to reward (more HR deceleration) and smaller HR reactivity to penalty. Correlation analyses showed that decreased HR responses to penalty were related to an increased preference for large rewards. No group differences were observed in skin conductance responses to reward or penalty.
Conclusions
The findings suggest that an increased preference for large rewards in children with ODD is related to a reduced cardiac reactivity to aversive stimuli. This confirms notions of impaired decision making and altered reinforcement sensitivity in children with ODD and adds to the literature linking altered autonomic control to antisocial behavior.

Aims In this study we investigated the effects of the physical work environment on two physiological measures of the stress response.Methods and results Circadian variations in vagally mediated heart rate variability (HRV) and the morning rise in cortisol were evaluated in 60 participants working in a government building either in a traditional (individual offices and old cubicles; n= 40) or a modern workspace (individualized cubicles with improved views and lighting; n= 20). Results revealed significant linear (B = 1.03; confidence interval: 1.05 to 1.01, P [ 0.05) and quadratic (B = 1.001; confidence interval: 1.00041.002, P [ 0.05) trends by office type interactions for indices of vagally mediated HRV. Individuals in the old office space had flatter slopes and thus less circadian variation including less HRV at night, and a larger rise in cortisol upon awakening compared with those in the new office space.Conclusion These results indicate that physical features of the work environment may affect two aspects of the physiological stress response: circadian variations in HRV and the morning rise in cortisol. These findings have important social, economic, and public health implications for work environment risk factors on health.

Reactive aggression (RA) is an angry response to perceived provocation. Proactive aggression (PA) is a pre-meditated act used to achieve some goal. This study test hypotheses that (1) individuals high in RA and PA will differ in resting levels of autonomic arousal and (2) RA will be related to emotional and behavioral problems, while PA only to behavioral problems. Parents of 68 children (age 6–13) reported on child symptoms, reactive/proactive aggression, and behavior problems. Resting heart rate (HR), skin conductance (SC), and HR variability (HRV) were measured in 42 of the children. RA was significantly related to decreased HRV and a trend for decreased SC, while PA was significantly related to increased SC and HRV. RA was significantly related to increased internalizing behaviors and attention deficits, while PA was significantly related to increased hyperactivity/impulsivity and delinquent behavior problems. Findings support a distinction between child reactive (hot-tempered) and proactive (cold-tempered) aggression in autonomic, emotional (i.e., internalizing problems), and behavioral (i.e., attention deficits, hyperactivity/impulsivity, and delinquent behavior) functioning, and are discussed in relation to theories of antisocial behavior.

Autonomic nervous system (ANS) specificity of emotion remains controversial in contemporary emotion research, and has received mixed support over decades of investigation. This study was designed to replicate and extend psychophysiological research, which has used multivariate pattern classification analysis (PCA) in support of ANS specificity. Forty-nine undergraduates (27 women) listened to emotion-inducing music and viewed affective films while a montage of ANS variables, including heart rate variability indices, peripheral vascular activity, systolic time intervals, and electrodermal activity, were recorded. Evidence for ANS discrimination of emotion was found via PCA with 44.6% of overall observations correctly classified into the predicted emotion conditions, using ANS variables (z=16.05, p<.001). Cluster analysis of these data indicated a lack of distinct clusters, which suggests that ANS responses to the stimuli were nomothetic and stimulus-specific rather than idiosyncratic and individual-specific. Collectively these results further confirm and extend support for the notion that basic emotions have distinct ANS signatures.

Questionnaire and interview assessment can provide reliable data on attitudes and self-perceptions on emotion, and experimental laboratory assessment can examine functional relations between stimuli and reactions under controlled conditions. On the other hand, ambulatory assessment is less constrained and provides naturalistic data on emotion in daily life, with the potential to (1) assure external validity of laboratory findings, (2) provide normative data on prevalence, quality and intensity of real-life emotion and associated processes, (3) characterize previously unidentified emotional phenomena, and (4) model real-life stimuli for representative laboratory research design. Technological innovations now allow for detailed ambulatory study of emotion across domains of subjective experience, overt behavior and physiology. However, methodological challenges abound that may compromise attempts to characterize biobehavioral aspects of emotion in the real world. For example, emotional effects can be masked by social engagement, mental and physical workloads, as well as by food intake and circadian and quasi-random variation in metabolic activity. The complexity of data streams and multitude of factors that influence them require a high degree of context specification for meaningful data interpretation. We consider possible solutions to typical and often overlooked issues related to ambulatory emotion research, including aspects of study design decisions, recording devices and channels, electronic diary implementation, and data analysis.

Context: Stress is suggested to lead to metabolic dysregulations as clustered in the metabolic syndrome, but the underlying biological mechanisms are not yet well understood.Objective: We examined the relationship between two main str systems, the autonomic nervous system and the hypothalamic-pituitary-adrenal (HPA) axis, with the metabolic syndrome and its components.Design: The design was baseline data (yr 2004–2007) of a prospective cohort: the Netherlands Study of Depression and Anxiety (NESDA).Setting: The study comprised general community, primary care, and specialized mental health care.Participants: This study included 1883 participants aged 18–65 yr.Main Outcome Measures: Autonomic nervous system measures included heart rate, respiratory sinus arrhythmia (RSA; high RSA reflecting high parasympathetic activity), and preejection period (PEP; high PEP reflecting low sympathetic activity). HPA axis measures included the cortisol awakening response, evening cortisol, and a 0.5 mg dexamethasone suppression test as measured in saliva. Metabolic syndrome was based on the updated Adult Treatment Panel III criteria and included high waist circumference, serum triglycerides, blood pressure, serum glucose, and low high-density lipoprotein cholesterol.Results: RSA and PEP were both independently negatively associated with the presence of the metabolic syndrome, the number of metabolic dysregulations as well as all individual components except high-density lipoprotein cholesterol (all P < 0.02). Heart rate was positively related to the metabolic syndrome, the number of metabolic dysregulations, and all individual components (all P < 0.001). HPA axis measures were not related to metabolic syndrome or its components.Conclusion: Our findings suggest that increased sympathetic and decreased parasympathetic nervous system activity is associated with metabolic syndrome, whereas HPA axis activity is not.