P.1.b.010 Effects of gabapentin on the contractility of gastric smooth muscles

Abstract

EEG recording 45 minutes after smoking their usual amount of cannabis (the drug samples were brought by users themselves). Only those subjects who had levels higher than 4 ng/ml were included in the EEG analysis (N = 13). The psychopathology during the experiment was assessed by the subjects themselves with ASCs and by the experimenter with BPRS. Both scales were applied 120 minutes after drug use and referred to the whole intoxication period. Regression analysis was performed using sLORETA to assess whether activity changes in the brain regions interrelated with the subscales of ASCs and BPRS. The significance of the regression coefficients was assessed using a randomization test that corrects for multiple comparisons to keep the family-wise Type I error rate to 0.05. Summary of results: Results were a negative correlation (r = −0.78, p< 0.05) between the Dread of ego-dissolution subscale of ASCs and sLORETA activity in the beta 3 frequency band in the Cingulate gyrus and Precuneus (corresponding Brodmann Areas: 7, 24, 31) and similarly there was a negative correlation (r = −0.72, p< 0.05) between the anxiety/depression subscale of BPRS and sLORETA activity in analogous brain structures in the beta 2, beta 3 and gamma frequency bands, suggesting a common underlying psychological phenomenon measured by both scales. Conclusions: The decrement of brain activity in midline parietal structures in higher frequency bands correlated with subjectively experienced Dread of ego-dissolution (i.e. anxiety, fear, selfdisorganization, derealization), as well as with the scores of anxiety/depression rated by the experimenter. These brain structures are thought to be involved in the Default Mode Network, where deactivations were reported in relation to different psychological states with pathophysiologically altered consciousness [1]. One of the main hubs of Default Mode Network, the precuneus, is involved in the representation of self and the external world [2], therefore its deactivation should result in self-disorganization and changes in the representation of the external world (as observed by increased scores of Dread of ego-dissolution). The observed increase in anxiety, which is a common denominator of both subscales (a correlation between subscales r = 0.42 was described [3]), may accompany such psychological changes.