Residual effects of hypnotics on disengagement of spatial attention

In an earlier study, we postulated that the residual effects of hypnotics could induce a spatial attention disengagement deficit independent of any decrease in alertness. To test this hypothesis, we compared the residual effects of zolpidem, zopiclone and flunitrazepam in two ocular saccade tests, gap and overlap. In the gap paradigm, the lateral target is illuminated 200 ms after the extinguishing of the central target. In the overlap paradigm, the central target stayed on when the lateral target was illuminated. Zopiclone increases latency in the overlap, but not in the gap test, which appears to be specific to a deficit of disengagement of spatial attention. Zopiclone impairs the saccadic precision in gap, but not in overlap, which may be interpreted as an impairment of visuospatial memory. The effects of zolpidem are limited to visuospatial impairment. The effects of flunitrazepam are massive and probably the results of a decrease in alertness.