BINOCULAR EYE-MOVEMENTS NOT COORDINATED DURING REM-SLEEP

Rapid eye movements (REMs) are a defining characteristic of REM sleep during which vivid dreams occur. It has been suggested that REMs may b e binocularly coordinated and related to ''watching'' dream images. Fo r the first time, binocular eye movements were recorded during natural REM sleep in monkeys to test the conjugate nature of the oculomotor s ystem and the ''scanning hypothesis'' of REMs during sleep. During REM sleep, the lines of sight of the two eyes are frequently misaligned u p to 30 degrees horizontally and/or vertically. Since the lines of sig ht usually don't intersect, there is no fixation point. In stead, each eye is aimed at a different part of the visual field during REM sleep . Furthermore, REMs are not usually conjugate, but are disjunctive or even monocular in horizontal or vertical directions. These data argue against the idea that REMs actually ''track'' dream images, unless eac h eye is watching its own dream! Binocular misalignment and disjunctiv e (even monocular) REMs during sleep suggest that separate left eye an d right eye pathways generate saccades in each eye and control the pos ition of each eye. Binocular coordination cannot be the passive result of anatomical connectivity as has been argued previously, but instead must result from a high-level process as sociated with the awake stat e that coordinates activity in left-eye and right-eye pathways. Hering 's law of equal innervation is not consistent with these data.