STATE-DEPENDENT RETRIEVAL AND MIDAZOLAM

This experiment investigated the phenomenon of state-dependent retrieval with midazolam by comparing performance after midazolam + placebo with that after reversal with the benzodiazepine antagonist flumazenil, in tests of explicit and semantic memory and judgements of recency. The subjects completed analogue rating scales and psychomotor tests to provide measures of sedation. Midazolam (0.05 mg/kg) impaired recall and recognition of pictures and performance in the digit-symbol substitution task. There were no significant state-dependent effects with this dose. Midazolam (0.075 mg/kg) impaired recall and recognition of words and pictures and recognition of coloured slides of complex scenes. There were significant state-dependent effects on all the recognition tests, i.e. the group tested after reversal with flumazenil (0.5 mg) performed worse than that tested after placebo. Midazolam (0.075 mg(kg) also impaired recency judgements and performance in the number cancellation and digit-symbol substitution tests, but there were no state-dependent effects in these tests. To determine whether subjects had insight into their memory impairments, for each task they were asked to rate on an analogue scale whether they thought their memory would be 'better or worse than usual'. Those tested with midazolam (0.075 mg/kg) showed no insight into their memory impairments and there were negative correlations between actual and estimated performance. However those reversed with flumazenil were aware their memory was worse than usual and had positive correlations between actual and estimated performance, similar to those shown by subjects tested undrugged.