Influence of emotional arousal on the N150 of the Auditory Evoked Potential from the rat amygdala.

This study tested whether a general increase in emotional arousal is a sufficient determinant for the evocation of the N150, a negative wave in amygdalar Auditory Evoked Potentials (AEPs). Rats received one of three conditioning protocols: either conditioned stimulus (CS) presentations alone (Control) CS-shock pairings (Paired) or unpaired presentations of the CS and shock (Unpaired). Amygdalar AEPs were recorded in response to the CS. It was hypothesized that if a state of emotional arousal is a sufficient condition for the manifestation of the N150, its amplitude should be enhanced in the Paired and Unpaired conditions relative to the Control condition, which was indeed found. In addition, it was found that the N150 had a larger amplitude in the Paired than in the Unpaired condition. This suggests that an additional N150 increase is established when animals learn the CS-US association. The results are discussed in relation to literature on amygdala function.

Effects of additional oxazepam in long-term users of oxazepam.

Although additional dosages of benzodiazepines in long-term users of benzodiazepines are common, it is unknown whether these additional dosages resort any effect. The effects of an additional 20-mg dosage oxazepam were assessed in a double-blind, balanced-order, crossover randomized study comparing 16 long-term users of oxazepam (patients) with 18 benzodiazepine-naive controls (controls). The effects of 10 and 30 mg oxazepam were assessed at pretest and 2.5 hours after drug administration on: (a) saccadic eye movements as proxy for the sedative effect, (b) acoustic startle response (ASR) as proxy for the anxiolytic effects, (c) memory, (d) reaction time tasks, and (e) subjective measurements. Dose-related effects were found in patients on the peak velocity of saccadic eye movement and on response probability, respectively peak amplitude of the ASR. Comparison with controls, however, suggests that in patients the sedative effects might be mixed up with suppression of sedative withdrawal symptoms, whereas patients were as sensitive as benzodiazepine-naive controls for the effects of an additional dosage on the ASR. Neither 10 nor 30 mg oxazepam challenge affected the reaction time tasks in patients, whereas controls show a dose-related impairment. The memory impairing effects, however, did not differ significantly between patients and controls. In contrast to controls, patients could not discriminate between a 10- and 30-mg dosage as assessed by visual analogue scales and the STAI-DY-1, which might indicate a placebo effect in the 10-mg challenge in patients. We conclude that additional dosages of oxazepam still exert pronounced effects after daily use for more than 10 years.