Volker Busch

Neuroplasticity: Changes in grey matter induced by training

Does the structure of an adult human brain alter in response to environmental demands? Here we use whole-brain magnetic-resonance imaging to visualize learning-induced plasticity in the brains of volunteers who have learned to juggle. We find that these individuals show a transient and selective structural change in brain areas that are associated with the processing and storage of complex visual motion. This discovery of a stimulus-dependent alteration in the brains macroscopic structure contradicts the traditionally held view that cortical plasticity is associated with functional rather than anatomical changes.

The Effect of Deep and Slow Breathing on Pain Perception, Autonomic Activity, and Mood Processing—An Experimental Study

OBJECTIVE Deep and slow breathing (DSB) techniques, as a component of various relaxation techniques, have been reported as complementary approaches in the treatment of chronic pain syndromes, but the relevance of relaxation for alleviating pain during a breathing intervention was not evaluated so far. METHODS In order to disentangle the effects of relaxation and respiration, we investigated two different DSB techniques at the same respiration rates and depths on pain perception, autonomic activity, and mood in 16 healthy subjects. In the attentive DSB intervention, subjects were asked to breathe guided by a respiratory feedback task requiring a high degree of concentration and constant attention. In the relaxing DSB intervention, the subjects relaxed during the breathing training. The skin conductance levels, indicating sympathetic tone, were measured during the breathing maneuvers. Thermal detection and pain thresholds for cold and hot stimuli and profile of mood states were examined before and after the breathing sessions. RESULTS The mean detection and pain thresholds showed a significant increase resulting from the relaxing DSB, whereas no significant changes of these thresholds were found associated with the attentive DSB. The mean skin conductance levels indicating sympathetic activity decreased significantly during the relaxing DSB intervention but not during the attentive DSB. Both breathing interventions showed similar reductions in negative feelings (tension, anger, and depression). CONCLUSION Our results suggest that the way of breathing decisively influences autonomic and pain processing, thereby identifying DSB in concert with relaxation as the essential feature in the modulation of sympathetic arousal and pain perception.

Reduced intra-cortical inhibition after sleep deprivation: A transcranial magnetic stimulation study

Sleep deprivation has multiple effects on brain function. It increases the risk for epileptic seizures both in healthy individuals and in patients with epilepsy. Furthermore it represents an effective antidepressive intervention with rapid onset. However, the mechanisms underlying these effects are still largely unknown. Transcranial magnetic stimulation (TMS) can be used as a non-invasive method for the measurement of motor cortex excitability. Here we used TMS for assessing sleep deprivation effects on cortical excitability in healthy individuals. Before and after 24 h of sleep deprivation, parameters of cortical excitability (resting motor threshold, short intracortical inhibition, intracortical facilitation, cortical silent period) were measured in a sample of 15 healthy volunteers (11 women, 4 men, aged between 21 and 30 years with a mean of 24.3±2.7 years). We detected a significant (p=0.042) reduction of short intracortical inhibition (SICI) after sleep deprivation. Motor threshold, intracortical facilitation and contralateral silent period remained unchanged. Our results confirm previous studies which have demonstrated changes of SICI after sleep deprivation. Our findings further suggest that the increased risk for epileptic seizures after sleep deprivation is mediated by a reduction of intracortical inhibition. Whether this mechanism is also involved in mediating the antidepressant effect of sleep deprivation has to be addressed by further studies in depressive patients.

Hypothalamic deep-brain stimulation modulates thermal sensitivity and pain thresholds in cluster headache

ABSTRACT Deep‐brain stimulation (DBS) of the posterior hypothalamus has been shown to be clinically effective for drug‐resistant chronic cluster headache, but the underlying mechanism is still not understood. The hypothalamus as an important centre of homeostasis is connected among others to the trigeminal system via the trigeminohypothalamic tract. We aimed to elucidate whether hypothalamic stimulation affects thermal sensation and pain perception only in the clinically affected region (the first trigeminal branch) or in other regions as well. Thus, we examined three groups: chronic cluster headache patients with unilateral DBS of the posterior hypothalamus (n = 11), chronic cluster headache patients without DBS (n = 15) and healthy controls (n = 29). Perception and pain thresholds for hot and cold stimuli were determined bilaterally in all subjects supraorbitally, at the forearm, and in the lower leg. In DBS patients, thresholds were determined with the stimulator activated and inactivated. Cold pain thresholds at the first trigeminal branch were increased on the stimulated side in the DBS group compared to healthy subjects (p = .015). The DBS group also had higher cold detection thresholds compared to non‐implanted cluster headache patients (p < .05). Short‐term interruption of stimulation did not induce any changes in DBS patients. Clinically relevant differences were found neither between non‐stimulated cluster headache patients and healthy controls nor between the affected and the non‐affected sides in the chronic cluster headache patients without DBS. These results support the notion that neurostimulation of the posterior hypothalamus is specific for cluster headache and only affects certain aspects of pain sensation.

Somatic Symptoms Evoked by Exam Stress in University Students: The Role of Alexithymia, Neuroticism, Anxiety and Depression

Objective The etiology of somatization is incompletely understood, but could be elucidated by models of psychosocial stress. Academic exam stress has effectively been applied as a naturalistic stress model, however its effect on somatization symptoms according to ICD-10 and DSM-IV criteria has not been reported so far. Baseline associations between somatization and personality traits, such as alexithymia, have been studied exhaustively. Nevertheless, it is largely unknown if personality traits have an explanatory value for stress induced somatization. Methods This longitudinal, quasi-experimental study assessed the effects of university exams on somatization — and the reversal of effects after an exam-free period. Repeated-observations were obtained within 150 students, measuring symptom intensity before, during and after an exam period, according to the Screening for Somatoform Symptoms 7-day (SOMS-7d). Additionally, self-reports on health status were used to differentiate between medically explained and medically unexplained symptoms. Alexithymia, neuroticism, trait-anxiety and baseline depression were surveyed using the Toronto-Alexithymia Scale (TAS-20), the Big-Five Personality Interview (NEO-FFI), the State Trait Anxiety Inventory (STAI) and Beck’s Depression Inventory (BDI-II). These traits were competitively tested for their ability to explain somatization increases under exam stress. Results Somatization significantly increased across a wide range of symptoms under exam stress, while health reports pointed towards a reduction in acute infections and injuries. Neuroticism, alexithymia, trait anxiety and depression explained variance in somatization at baseline, but only neuroticism was associated with symptom increases under exam stress. Conclusion Exam stress is an effective psychosocial stress model inducing somatization. A comprehensive quantitative description of bodily symptoms under exam stress is supplied. The results do not support the stress-alexithymia hypothesis, but favor neuroticism as a personality trait of importance for somatization.

Sleep deprivation in chronic somatoform pain-effects on mood and pain regulation.

Sleep deprivation was found to exert complex effects on affective dimensions and modalities of pain perception both in healthy volunteers and patients with major depression. Considering multifaceted links between mood and pain regulation in patients with chronic somatoform pain, it is intriguing to study sleep deprivation effects for the first time in this group of patients. Twenty patients with a somatoform pain disorder according to ICD-10 diagnostic criteria were sleep-deprived for one night, followed by one recovery night. Clinical pain complaints (visual analog scale), detection- and pain thresholds (temperature and pressure) as well as mood states (Profile of Mood States) were assessed on the day prior to the experiment, on the day after sleep deprivation and on the day after recovery sleep. We found a discrepancy between significantly increased clinical pain complaints and unaltered experimental pain perception after sleep deprivation. Only the clinical pain complaints, but not the experimental pain thresholds were correlated with tiredness-associated symptoms. Total mood disturbances decreased and feelings of depression and anger improved significantly after sleep deprivation. However, these changes were not correlated with a change in clinical pain perception. We conclude that sleep deprivation may generally change the reagibility of the limbic system, but mood processing and pain processing may be affected in an opposite way reflecting neurobiological differences between emotional regulation and interoceptive pain processing.

rTMS over the cerebellum modulates temperature detection and pain thresholds through peripheral mechanisms

BACKGROUND Repetitive transcranial magnetic stimulation (rTMS) of motor and prefrontal cortex has been shown to modulate pain perception. Even though evidence suggests an involvement of cerebellar structures in pain processing, the effect of rTMS over the cerebellum on pain perception has not yet been investigated. OBJECTIVE/HYPOTHESIS This study aimed to test the effects of rTMS over the cerebellum on sensory perception, particularly controlling for peripheral stimulation effects. METHODS Sensory perception was determined as temperature detection and temperature pain thresholds. Experiment one explored the effects of four different rTMS protocols (flat figure-of-eight coil; 120% motor resting threshold; 1000 stimuli; 1 Hz and 10 Hz; medial and right lateral cerebellum) on sensory thresholds in 10 healthy volunteers using pairwise comparisons. The most efficient protocol of experiment one was compared in a second experiment with two control conditions (rTMS with a sham coil over the cerebellum [sham] and repetitive magnetic stimulation [rMS] of the neck) by using robust statistics (MANOVA). RESULTS The first experiment demonstrated pronounced effects on sensory perception for 1Hz rTMS over the lateral cerebellum. The second experiment confirmed this result in comparison to sham. However, rMS over the neck had a similar effect like rTMS over the cerebellum. CONCLUSIONS Our findings suggest that changes in sensory perception after rTMS over the cerebellum are largely due to stimulation effects on peripheral structures and support recent reports of analgesic effects of neck rMS. They advocate the critical review of the proposed analgesic effects of rTMS and encourage the future use of proper control conditions in rTMS research.

Sleep Quality during Exam Stress: The Role of Alcohol, Caffeine and Nicotine

Academic exam stress is known to compromise sleep quality and alter drug consumption in university students. Here we evaluated if sleeping problems and changes in legal drug consumption during exam stress are interrelated. We used the Pittsburgh Sleep Quality Index (PSQI) to survey sleep quality before, during, and after an academic exam period in 150 university students in a longitudinal questionnaire study. Self-reports of alcohol, caffeine, and nicotine consumption were obtained. The Perceived Stress Questionnaire (PSQ-20) was used as a measure of stress. Sleep quality and alcohol consumption significantly decreased, while perceived stress and caffeine consumption significantly increased during the exam period. No significant change in nicotine consumption was observed. In particular, students shortened their time in bed and showed symptoms of insomnia. Mixed model analysis indicated that sex, age, health status, as well as the amounts of alcohol and caffeine consumed had no significant influence on global sleep quality. The amount of nicotine consumed and perceived stress were identified as significant predictors of diminished sleep quality. Nicotine consumption had a small-to-very-small effect on sleep quality; perceived stress had a small-to-moderate effect. In conclusion, diminished sleep quality during exam periods was mainly predicted by perceived stress, while legal drug consumption played a minor role. Exam periods may pose an interesting model for the study of stress-induced sleeping problems and their mechanisms.

Theory of Mind and Emotional Awareness in Chronic Somatoform Pain Patients.

Objective The present study aimed at investigating whether chronic pain patients are impaired in Theory of Mind (ToM), or Emotional Awareness. Methods Thirty inpatients suffering from chronic somatoform pain, as well as thirty healthy controls matched for age, sex, and education were recruited. ToM abilities were measured using the Frith-Happé animation task, in which participants interpret video-clips depicting moving geometric forms that mimic social interactions. The responses given were scored for appropriateness and the degree of inferred intentionality according to established protocols. Emotional awareness was measured using the Levels of Emotional Awareness Scale (LEAS), for which participants provide written descriptions of feelings in imaginary emotional situations. Standardized scoring was performed to capture the number and quality of emotional terms used. Results Responses lengths were similar in both groups and for both tasks. Patients attained significantly lower intentionality but not appropriateness scores when interpreting ToM interactions. No significant group differences were found when interpreting goal directed interactions. Emotional awareness scores were significantly lower in patients compared to healthy controls. Conclusions Our results suggest that chronic pain patients are impaired in mentalizing and emotional awareness. Future studies are needed to determine whether these ToM and emotional awareness deficits contribute to the etiology of somatoform pain and whether addressing these deficits in therapeutic interventions can improve polymodal pain therapy.

Severe chronic insomnia is not associated with higher body mass index.

Short sleep duration is widely considered to be a risk factor for weight gain, suggesting that patients suffering from sleep disorders are a risk group. Despite some positive preliminary data on patients with organic sleep disorders, empirical evidence for an increased body mass index in patients with insomnia is scarce. Two‐hundred and thirty‐three patients with a confirmed diagnosis of severe and chronic insomnia without co‐morbidity showing objectively impaired sleep quality were compared with respect to their body mass index with control data derived from a representative population survey matched in gender and age. As a result, patients with insomnia showed a lower body mass index (23.8 kg m−2 versus 27.1 kg m−2; P < 0.0005). Our findings suggest that patients with chronic insomnia do not exhibit overweight. These data are a valuable educational tool to calm patients’ fears about the consequences of insomnia, and contribute to the understanding of chronically disturbed sleep and weight regulation.