fMRI Revealed Reduced Amygdala Activation after Nx4 in Mildly to Moderately Stressed Healthy Volunteers in a Randomized, Placebo-Controlled, Cross-Over Trial.

Social stress contributes to major societal health burdens, such as anxiety disorders and nervousness. Nx4 has been found to modulate stress responses. We investigated whether dampening of such responses is associated with neuronal correlates in brain regions involved in stress and anxiety. In a randomized, placebo-controlled, double-blind, cross-over trial, 39 healthy males took a single dose (three tablets) of either placebo or Nx4, 40 to 60 minutes before an fMRI scan session. We here report on drug effects on amygdala responses during a face-matching task, which was performed during a complex test battery further including resting-state brain connectivity and a social stress experiment. The first of the Primary Outcomes, defined in a hierarchical order, concerned reduced amygdala effects after intake of verum compared to placebo. We found a statistically significant reduction in differential activations in the left amygdala for the contrast negative faces versus forms during verum versus placebo condition. Our results indicate that effects of Nx4 can be monitored in the brain. Previously noted effects on stress responses may thus be modulated by affective brain regions including the amygdala.

Structural brain changes in young males addicted to video-gaming.

Excessive video gaming has a number of psychological and social consequences. In this study, we looked at possible changes in gray and white matter and asked whether these changes are correlated to psychological measures. Twentynine players of violent videogames (mean daily playing time 4.7 h) and age matched controls were subjected to a battery of questionnaires assessing aggression, empathy, hostility, internet addiction and psychological well-being. Diffusion tensor and 3D T1-weighted MR images were obtained to examine gray (via voxel-based morphometry) and white (via tract-based spatial statistics) matter changes. Widespread regions of decreased gray matter in the players were found but no region showed increased intensity of gray matter. Density of gray matter showed a negative correlation with the total length of playing in years in the right posterior cingulate gyrus, left pre- and postcentral gyrus, right thalamus, among others. Furthermore, fractional anisotropy, a marker for white matter structure, was decreased in the left and right cingulum in the players. Both, gray and white matter changes correlated with measures of aggression, hostility, self esteem, and the degree of internet addiction. This study thus shows profound changes of brain structure as a function of excessive playing of violent video games.

Deficient prepulse inhibition of the startle reflex in schizophrenia using a cross-modal paradigm.

OBJECTIVES: To investigate whether the typically reported deficient sensorimotor gating in patients with schizophrenia using unimodal paradigms can also be detected by a cross-modal paradigm which made use of an electrocutaneous-acoustic coupling of stimuli. METHODS: Twenty-one male schizophrenia patients took part in a prepulse inhibition (PPI) paradigm with an electrocutaneous prepulse and an acoustic startle-eliciting pulse. Their results were compared with those from nineteen healthy males. RESULTS: As expected, the patients showed significantly lower PPI than controls. No associations were found between measures of illness severity and PPI. DISCUSSION: To the best of our knowledge, this is the first study showing reduced PPI in patients with schizophrenia by using an electrocutaneous-acoustic prepulse-pulse combination. Hence, this study gives further evidence of a modality-independent sensorimotor gating deficit in schizophrenia. Furthermore, as PPI was also lower than usual in controls using unimodal paradigms, results are interpreted in favour of longer processing times of the electrocutaneous prepulse, which probably led to a shorter perceived stimulus onset asynchrony (SOA) in the brain.

Reduced audiovisual integration in synesthesia--evidence from bimodal speech perception.

Recent research suggests synesthesia as a result of a hypersensitive multimodal binding mechanism. To address the question whether multimodal integration is altered in synesthetes in general, grapheme-colour and auditory-visual synesthetes were investigated using speech-related stimulation in two behavioural experiments. First, we used the McGurk illusion to test the strength and number of illusory perceptions in synesthesia. In a second step, we analysed the gain in speech perception coming from seen articulatory movements under acoustically noisy conditions. We used disyllabic nouns as stimulation and varied signal-to-noise ratio of the auditory stream presented concurrently to a matching video of the speaker. We hypothesized that if synesthesia is due to a general hyperbinding mechanism this group of subjects should be more susceptible to McGurk illusions and profit more from the visual information during audiovisual speech perception. The results indicate that there are differences between synesthetes and controls concerning multisensory integration--but in the opposite direction as hypothesized. Synesthetes showed a reduced number of illusions and had a reduced gain in comprehension by viewing matching articulatory movements in comparison to control subjects. Our results indicate that rather than having a hypersensitive binding mechanism, synesthetes show weaker integration of vision and audition.

Electrophysiological attention effects in a virtual cocktail-party setting.

The selection of one of two concurrent speech messages for comprehension was investigated in healthy young adults in two event-related potential experiments. The stories were presented from virtual locations located 30 degrees to the left and right azimuth by convolving the speech message by the appropriate head-related transfer function determined for each individual participant. In addition, task irrelevant probe stimuli were presented in rapid sequence from the same virtual locations. In experiment 1, phoneme probes (/da/ voiced by the same talkers as attended and unattended messages) and band-pass filtered noise probes were presented. Phoneme probes coinciding with the attended message gave rise to a fronto-central negativity similar to the Nd-attention effect relative to the phoneme probes coinciding with the unattended speech message, whereas noise probes from the attended message's location showed a more positive frontal ERP response compared to probes from the unattended location resembling the so-called rejection positivity. In experiment 2, phoneme probes (as in exp. 1) and frequency-shifted (+400 Hz) were compared. The latter were characterized by a succession of negative and positive components that were modulated by location. The results suggest that at least two different neural mechanisms contribute to stream segregation in a cocktail-party setting: enhanced neural processing of stimuli matching the attended message closely (indexed by the Nd-effect) and rejection of stimuli that do not match the attended message at the attended location only (indexed by the rejection positivity).