The Power of mind: Blocking visual perception by hypnosis.

The present study investigated the effects of suggestion on the processing of visual stimuli. Participants counted rare visual stimuli presented on a screen, once during a hypnosis condition where they were suggested that their vision of the screen is blocked by a virtual wooden board in front of their eyes and once during a control condition without suggestion. In the hypnosis condition, counting performance was about 20% worse than in the control condition. At the same time, the P3b amplitude of the event-related brain potential was about 37% reduced. Smaller P3b amplitudes were significantly associated with deficient counting performance, and this effect was largest in participants who reported the blockade as real. In contrast, earlier brain responses (N1, P2) that reflect basic processing of the visual stimuli were not affected by the suggested blockade. We conclude that the suggestion of the blockade affects later stages of visual perception, leaving early processes intact. This illustrates the impact of suggestions and the power of mind.

Altered activation of the ventral striatum under performance-related observation in social anxiety disorder.

BACKGROUND: Social anxiety disorder (SAD) is characterized by fear of social and performance situations. The consequence of scrutiny by others for the neural processing of performance feedback in SAD is unknown. METHODS: We used event-related functional magnetic resonance imaging to investigate brain activation to positive, negative, and uninformative performance feedback in patients diagnosed with SAD and age-, gender-, and education-matched healthy control subjects who performed a time estimation task during a social observation condition and a non-social control condition: while either being monitored or unmonitored by a body camera, subjects received performance feedback after performing a time estimation that they could not fully evaluate without external feedback. RESULTS: We found that brain activation in ventral striatum (VS) and midcingulate cortex was modulated by an interaction of social context and feedback type. SAD patients showed a lack of social-context-dependent variation of feedback processing, while control participants showed an enhancement of brain responses specifically to positive feedback in VS during observation. CONCLUSIONS: The present findings emphasize the importance of social-context processing in SAD by showing that scrutiny prevents appropriate reward-processing-related signatures in response to positive performances in SAD.

Laser heat hyperalgesia is not a feature of non-specific chronic low back pain.

BACKGROUND: Based upon studies using mechanical pin-prick, pressure, electrical or heat stimuli applied to painful and/or pain-free parts of the body, chronic low back pain (CLBP) has been shown to be associated with generalized and enhanced pain sensitivity and altered brain responses to noxious stimuli. To date, no study examined the processing of noxious laser heat pulses, which are known to selectively excite thermal nociceptors located in the superficial skin layers, in CLBP. METHODS: We studied laser heat pain thresholds (LHPTs) and nociceptive laser-evoked brain electrical potentials (LEPs) following skin stimulation of the pain-affected back and the pain-free abdomen using noxious laser heat stimulation in 16 CLBP patients and 16 age- and gender-matched healthy controls (HCs). RESULTS: We observed no statistically significant differences in LHPTs between CLBP patients and HCs, neither on the back nor on the abdomen. Furthermore, we found no evidence for altered brain responses between CLBP patients and HCs in response to stimulation of the back and abdomen in single-trial latencies and amplitudes of LEP components (N2, P2). CONCLUSION: The results are in contrast to previous studies showing hypersensitivity to different experimental noxious stimuli (e.g., contact heat). We argue that these discrepancies may be due to low spatial and temporal summation within the central nervous system following laser heat stimulation. Our results indicate important methodological differences between laser heat and thermode stimulation that should be taken into account when interpreting results, such as from thermal quantitative sensory testing.

[Emotional impact of facial palsy]. / Emotionale Auswirkungen einer Fazialisparese.

Facial palsy is not only a movement disorder but leads also to an emotional and communicative disorder in chronic stage but also in some patients already during the acute phase of the disease. The present review describes the current knowledge of the neurobiological and psychological fundamentals on the relation of facial movement and its emotional context. So far there is not much knowledge on the impact of a facial palsy on the interaction between facial movement, emotional processing and communicative skills of the patient. The emotional contagion seems to be reduced in patients with facial palsy. The ability to express emotions seems also to be reduced. Moreover, the patients feel to be perceived negatively. In fact, most of the expressions of patients with facial palsy are allocated with a negative affect even when the patients are smiling. Patients with facial palsy react with negative stress, anxiety and depression. The patients avoid social contacts. In turn, this reinforces the communicative disorder. The otorhinolaryngologist can use the Facial Disability Index as a simple questionnaire to detect such dysfunctions. Diagnostics that are necessary to develop a therapy program are presented in this review. Standardized therapy concepts that are not only treat the movement disorder but also the emotional context is missing so far. Finally, the review will give an outlook on potential therapy strategies.

Connectivity analysis of somatosensory evoked potentials in patients with major depression. Analysis of connectivity.

OBJECTIVES: Connectivity analysis was used to investigate the processing of intracutaneous stimuli and directed interactions within the pain matrix in patients with major depression (MD) and healthy controls (HCs), by means of frequency selective generalized partial directed coherence (gPDC). METHODS: Eighteen patients with MD and 18 HCs underwent stimulations consisting of moderately painful intracutaneous electrical stimuli to the right and left middle fingers. Connectivity analysis was based on nine selected EEG electrodes. RESULTS: Stimulus-induced changes of the gPDC in a pre/post stimulus comparison and changes in the connectivity pattern in the post-stimulus condition were found. We could identify network changes correlating to the side stimulated, as well as differences between HCs and MD patients. CONCLUSIONS: These data support the suggestion that pain processing in response to noxious stimulation in MD patients is different compared to healthy controls, suggesting aberrant functional connectivity. Generalized partial directed coherence is shown to be a promising method to detect changes in connectivity in both within- and between-subject designs.

[Stimulation of tiny skin areas for selective stimulation of C fibres]. / Selektive C-Faser-Stimulation durch Stimulation winziger Hautareale.

BACKGROUND: It has been found difficult to stimulate the primary C-fibre afferents separately from those of Adelta fibres. A necessary and sufficient condition for the investigation of the C-fibre system is the selective stimulation of C fibres without activation of Adelta fibres. The stimulation of tiny skin areas allows such a selective activation of C fibres. METHODS AND RESULTS: The main aspects of the method for stimulation of tiny skin areas as well as some results obtained by this method are reported here. The application of this method is compared with applications of other methods that allow an investigation of central processing of human C-fibre input. CONCLUSION: The stimulation of tiny skin areas represents a simple method for selective stimulation of C fibres.