Jens Blechert

Autonomic and Respiratory Characteristics of Posttraumatic Stress Disorder and Panic Disorder

Objective: Posttraumatic stress disorder (PTSD) and panic disorder (PD) are two anxiety disorders with prominent psychophysiological symptoms. The PTSD criterion of persistent hyperarousal suggests autonomic dysregulation, and the disorder has been associated with elevated heart rate. In contrast, PD has been associated with respiratory abnormalities such as low end-tidal Pco2. An integrated analysis of automatic and respiratory function in a direct comparison of these anxiety disorders is currently lacking. Methods: Electrodermal, cardiovascular, and respiratory psychophysiology was examined in 23 PTSD patients, 26 PD patients, and 32 healthy individuals at baseline and during threat of shock. Results: At baseline, the PTSD patients, in contrast to the other two groups, were characterized by attenuated parasympathetic and elevated sympathetic control, as evidenced by low respiratory sinus arrhythmia (a measure of cardiac vagal control) and high electrodermal activity. They also displayed elevated heart rate and cardiovascular sympathetic activation in comparison with healthy controls. PD patients exhibited lower Pco2 (hypocapnia) and higher cardiovascular sympathetic activation compared with healthy controls. PTSD patients, but not PD patients, sighed more frequently than controls. During the threat of shock phase, the PTSD group demonstrated blunted electrodermal responses. Conclusions: Persistent hyperarousal symptoms in PTSD seem to be due to high sympathetic activity coupled with low parasympathetic cardiac control. Respiratory abnormalities were also present in PTSD. Several psychophysiological measures exhibited group-comparison effect sizes in the order of 1.0, supporting their potential for enhancing differential diagnosis and possibly suggesting utility as endophenotypes in genetic studies of anxiety disorders. CSI = cardiovascular sympathetic index; CVT = cardiac vagal tone; ESI = electrodermal sympathetic index; HR = heart rate; HP = heart period; RSA = respiratory sinus arrhythmia; NS-SCR = number of nonspecific skin conductance fluctuations; HRV = heart rate variability; SCL = skin conductance level; Pco2 = end-tidal partial pressure of expired CO2; PDS = Posttraumatic Diagnostic Scale; PTSD = posttraumatic stress disorder; PD = panic disorder; STAI = State-Trait Anxiety Inventory; BDI = Beck Depression Inventory; SCRamp = amplitude of nonspecific skin conductance responses; ECG = electrocardiogram; lnHF = high-frequency power of HP variability; lnLF = low-frequency power of HP variability; lnVLF = very low-frequency power of HP variability; MANOVA = multivariate analysis of variance; HC = healthy controls.

Fear conditioning in panic disorder: Enhanced resistance to extinction.

Enhanced conditionability has been proposed as a crucial factor in the etiology and maintenance of panic disorder (PD). To test this assumption, the authors of the current study examined the acquisition and extinction of conditioned responses to aversive stimuli in PD. Thirty-nine PD patients and 33 healthy control participants took part in a differential aversive conditioning experiment. A highly annoying but not painful electrical stimulus served as the unconditioned stimulus (US), and two neutral pictures were used as either the paired conditioned stimulus (CS+) or the unpaired conditioned stimulus (CS-). Results indicate that PD patients do not show larger conditioned responses during acquisition than control participants. However, in contrast to control participants, PD patients exhibited larger skin conductance responses to CS+ stimuli during extinction and maintained a more negative evaluation of them, as indicated by valence ratings obtained several times throughout the experiment. This suggests that PD patients show enhanced conditionability with respect to extinction.

The temporal dynamics of emotion regulation: An EEG study of distraction and reappraisal

Distraction and reappraisal are two widely used forms of emotion regulation. The process model of emotion regulation (Gross, 1998) holds that they differ (1) in when they act on the emotion-generative process, and (2) in their impact on subsequent responses to regulated stimuli. We tested these two predictions by measuring electrocortical responses to neutral and emotional images during two phases. In the regulation phase, images were watched or regulated using distraction or reappraisal. During the re-exposure phase, the same images were passively watched. As predicted, during regulation, distraction reduced the late positive potential (LPP) earlier than reappraisal. Upon re-exposure, images with a distraction (but not reappraisal) history elicited a larger LPP than images with an attend history. This pattern of results suggests that distraction and reappraisal intervene at separate stages during emotion generation, a feature which may have distinct consequences that extend beyond the regulatory episode.

Emotion regulation choice: A conceptual framework and supporting evidence

Choice behavior is considered the fundamental means by which individuals exert control over their environments. One important choice domain that remains virtually unexplored is that of emotion regulation. This is surprising given that healthy adaptation requires flexibly choosing between regulation strategies in a manner that is responsive to differing situational demands. In the present article, we provide a broad conceptual framework that systematically evaluates the rules that govern the ways individuals choose between different emotion regulation strategies. This conceptual account is buttressed by empirical findings from 6 studies that show the effects of hypothesized emotional, cognitive, and motivational determinants of regulation choice (Studies 1-3) and illuminate the mechanisms that underlie choices between different emotion regulation strategies (Studies 4-6). Broad implications and future directions are discussed.

Food-pics: an image database for experimental research on eating and appetite.

Our current environment is characterized by the omnipresence of food cues. The sight and smell of real foods, but also graphically depictions of appetizing foods, can guide our eating behavior, for example, by eliciting food craving and influencing food choice. The relevance of visual food cues on human information processing has been demonstrated by a growing body of studies employing food images across the disciplines of psychology, medicine, and neuroscience. However, currently used food image sets vary considerably across laboratories and image characteristics (contrast, brightness, etc.) and food composition (calories, macronutrients, etc.) are often unspecified. These factors might have contributed to some of the inconsistencies of this research. To remedy this, we developed food-pics, a picture database comprising 568 food images and 315 non-food images along with detailed meta-data. A total of N = 1988 individuals with large variance in age and weight from German speaking countries and North America provided normative ratings of valence, arousal, palatability, desire to eat, recognizability and visual complexity. Furthermore, data on macronutrients (g), energy density (kcal), and physical image characteristics (color composition, contrast, brightness, size, complexity) are provided. The food-pics image database is freely available under the creative commons license with the hope that the set will facilitate standardization and comparability across studies and advance experimental research on the determinants of eating behavior.

Intuitive eating is associated with interoceptive sensitivity. Effects on body mass index.

Intuitive eating is relevant for adaptive eating, body weight and well-being and impairments are associated with dieting and eating disorders. It is assumed to depend on the ability to recognize ones signs of hunger and fullness and to eat accordingly. This suggests a link to the individual ability to perceive and processes bodily signals (interoceptive sensitivity, IS) which has been shown to be associated with emotion processing and behavior regulation. This study was designed to clarify the relationships between IS as measured by a heartbeat perception task, intuitive eating and body mass index (BMI) in N=111 healthy young women. Intuitive eating was assessed by the Intuitive Eating Scale (IES) with three facets, reliance on internal hunger and satiety cues (RIH), eating for physical rather than emotional reasons (EPR), and unconditional permission to eat when hungry (UPE). IS was not only positively related to total IES score and RIH and EPR, and negatively predicted BMI, but also proved to fully mediate the negative relationship between RIH, as well as EPR and BMI. Additionally, the subjective appraisal of ones interoceptive signals independently predicted EPR and BMI. IS represents a promising mechanism in research on eating behavior and body weight.

Orbitofrontal reward sensitivity and impulsivity in adult attention deficit hyperactivity disorder

Impulsivity symptoms of adult attention deficit hyperactivity disorder (ADHD) such as increased risk taking have been linked with impaired reward processing. Previous studies have focused on reward anticipation or on rewarded executive functioning tasks and have described a striatal hyporesponsiveness and orbitofrontal alterations in adult and adolescent ADHD. Passive reward delivery and its link to behavioral impulsivity are less well understood. To study this crucial aspect of reward processing we used functional magnetic resonance imaging (fMRI) combined with electrodermal assessment in male and female adult ADHD patients (N=28) and matched healthy control participants (N=28) during delivery of monetary and non-monetary rewards. Further, two behavioral tasks assessed risky decision making (game of dice task) and delay discounting. Results indicated that both groups activated ventral and dorsal striatum and the medial orbitofrontal cortex (mOFC) in response to high-incentive (i.e. monetary) rewards. A similar, albeit less strong activation pattern was found for low-incentive (i.e. non-monetary) rewards. Group differences emerged when comparing high and low incentive rewards directly: activation in the mOFC coded for the motivational change in reward delivery in healthy controls, but not ADHD patients. Additionally, this dysfunctional mOFC activity in patients correlated with risky decision making and delay discounting and was paralleled by physiological arousal. Together, these results suggest that the mOFC codes reward value and type in healthy individuals whereas this function is deficient in ADHD. The brain-behavior correlations suggest that this deficit might be related to behavioral impulsivity. Reward value processing difficulties in ADHD should be considered when assessing reward anticipation and emotional learning in research and applied settings.

Learning as a Model for Neural Plasticity in Major Depression

BACKGROUND The neuroplasticity hypothesis of depression proposes that a dysfunction of neural plasticity-the basic ability of living organisms to adapt their neural function and structure to external and internal cues-might represent a final common pathway underlying the biological and clinical characteristics of the disorder. This study examined learning and memory as correlates of long-term synaptic plasticity in humans to further test the neuroplasticity hypothesis of depression. METHODS Learning in three tasks, for which memory consolidation has been shown to depend on local synaptic refinement in areas of interest (hippocampus-dependent declarative word-pair learning, amygdala-dependent fear conditioning, and primary-cortex-dependent visual texture discrimination), was assessed in 23 inpatients who met International Classification of Disease, 10th Revision, criteria for severe unipolar depression and 35 nondepressed comparison subjects. RESULTS Depressed subjects showed a significant deficit in declarative memory consolidation and enhanced fear acquisition as indicated by skin conductance responses to conditioned stimuli, in comparison with nondepressed subjects. Depressed subjects demonstrated impaired visual discrimination at baseline, not allowing for valid group comparisons of gradual improvement, the plasticity-dependent phase of the task. CONCLUSIONS The results of the study are consistent with the neuroplasticity hypothesis of depression, showing decreased synaptic plasticity in a dorsal executive network that comprises the hippocampus and elevated synaptic plasticity in a ventral emotional network that includes the amygdala in depression. Evaluation of further techniques aimed at modulating synaptic plasticity might prove useful for developing novel treatments for major depressive disorder.

Experiential, autonomic, and neural responses during threat anticipation vary as a function of threat intensity and neuroticism☆

Anticipatory emotional responses play a crucial role in preparing individuals for impending challenges. They do this by triggering a coordinated set of changes in behavioral, autonomic, and neural response systems. In the present study, we examined the biobehavioral impact of varying levels of anticipatory anxiety, using a shock anticipation task in which unpredictable electric shocks were threatened and delivered to the wrist at variable intervals and intensities (safe, medium, strong). This permitted investigation of a dynamic range of anticipatory anxiety responses. In two studies, 95 and 51 healthy female participants, respectively, underwent this shock anticipation task while providing continuous ratings of anxiety experience and electrodermal responding (Study 1) and during fMRI BOLD neuroimaging (Study 2). Results indicated a step-wise pattern of responding in anxiety experience and electrodermal responses. Several brain regions showed robust responses to shock anticipation relative to safe trials, including the hypothalamus, periaqueductal gray, caudate, precentral gyrus, thalamus, insula, ventrolateral PFC, dorsomedial PFC, and ACC. A subset of these regions demonstrated a linear pattern of increased responding from safe to medium to strong trials, including the bilateral insula, ACC, and inferior frontal gyrus. These responses were modulated by individual differences in neuroticism, such that those high in neuroticism showed exaggerated anxiety experience across the entire task, and reduced brain activation from medium to strong trials in a subset of brain regions. These findings suggest that individual differences in neuroticism may influence sensitivity to anticipatory threat and provide new insights into the mechanism through which neuroticism may confer risk for developing anxiety disorders via dysregulated anticipatory responses.

Restricted Autonomic Flexibility in Children with Social Phobia.

BACKGROUND Psychophysiological hyperresponsiveness to social-evaluative stress plays a key role in current theories of social phobia (SP). Owing to the early onset of this disorder, the study of children with SP can help to improve etiological models. However, research to date has failed to clarify whether children with SP are physiologically hyperresponsive to stress or not. In addition, the existence of elevated pre-stressor baseline group differences complicates the interpretation of acute stress responses and therefore poses a challenge for this line of research. Drawing on current models of autonomic control to explain the relationship between baseline and stress responding in SP children and healthy controls (HC), we acquired a broad set of autonomic measures in our study. METHOD To index baseline and stress reactivity and to assess autonomic flexibility, we assessed a comprehensive array of sympathetic and parasympathetic measures in SP children (aged 8 to 12 years; n = 30) and healthy control children (HC, n = 26), while exposing them to the Trier Social Stress Test for Children (TSST-C). RESULTS At baseline, the SP children showed higher levels of sympathetic (heart rate, electrodermal activity) and lower levels of parasympathetic (respiratory sinus arrhythmia, RSA) activation when compared to the HC children. During the TSST-C, the SP children showed similar HR responses but a limited RSA reactivity and a slower HR recovery relative to the HC children. CONCLUSION Our study extends previous research by showing elevated baseline arousal and comparable stress responding in SP children relative to HC children. In addition, based on the autonomic flexibility model, we provide a potential explanation for the null findings of previous studies during stress. The pattern of elevated baseline heart rates and reduced RSA point to restricted autonomic flexibility in children with SP.