Distortions of vision and pain: two functional facets of D-lysergic acid diethylamide.

D-lysergic acid diethylamide (LSD) produces distortions of visual perception and analgesia. Evidence is advanced from a functional standpoint that the observed visual effects result from an attenuation of light-evoked input to the dorsal lateral geniculate nucleus (LGN) from the purely centripetal pathways of the retina. More slowly responding visual afferents or those with more complex receptive fields seem to be affected most. LSD analgesia, accompanied by severe psychotic symptoms, appears to result from drug actions on a centrifugally controlled pain system involving neurons of the midbrain raphe.