Rapid eye movements (REMs) and visual dreams are salient features of REM sleep. However, it is unclear whether the eyes scan dream images. Several lines of evidence oppose the scanning hypothesis: REMs persist in animals and humans without sight (pontine cats, foetus, neonates, born-blinds), some binocular REMs are not conjugated (no focus point), REMs occur in parallel (not in series) with the stimulation of the visual cortex by ponto-geniculo-occipital spikes, and visual dreams can be obtained in non REM sleep. Studies that retrospectively compared the direction of REMs to dream recall recorded after having awakened the sleeper yielded inconsistent results, with a concordance varying from 9 to 80%. However, this method was subject to methodological flaws, including the bias of retrospection and neck atonia that does not allow the determination of the exact direction of gaze. Using the model of RBD (in which patients are able to enact their dreams due to the absence of muscle atonia) in 56 patients, we directly determined if the eyes moved in the same directions as the head and limbs. When REMs accompanied goal-oriented motor behaviour during RBD (e.g., framing something, greeting with the hand, climbing a ladder), 90% were directed towards the action of the patient (same plane and direction). REMs were however absent in 38% of goal-oriented behaviours. This directional coherence between limbs, head and eye movements during RBD suggests that, when present, REMs imitate the scanning of the dream scene. Because REMs index and complexity were similar in patients with RBD and controls, this concordance can be extended to normal REM sleep. These results are consistent with the model of a brainstem generator activating simultaneously images, sounds, limbs movements and REMs in a coordinated parallel manner, as in a virtual reality.

中文翻译：

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快速眼动睡眠期间眼睛快速运动的“扫描假说”：证据的回顾。

快速眼动（REM）和视觉梦想是REM睡眠的重要特征。但是，尚不清楚眼睛是否扫描梦境图像。几条证据反对扫描假说：REM在动物和人类中无视（猫，猫，胎儿，新生儿，天生瞎子）持续存在，一些双眼REM没有共轭（无焦点），REM并行发生（不是串联发生） ）通过脑桥枕枕尖刺激视觉皮层，在非REM睡眠中可以实现视觉梦想。回顾性地比较了唤醒睡眠者后记录的REM与梦回回忆的方向的研究结果不一致，一致性从9％到80％不等。但是，这种方法存在方法上的缺陷，包括回溯和颈部无力状态的偏差，这些偏差无法确定凝视的确切方向。使用RBD模型（其中由于没有肌肉肌萎缩症，患者能够实现梦想），我们对56名患者进行了建模，我们直接确定了眼睛是否朝着与头部和四肢相同的方向移动。当REM在RBD期间伴随着目标导向的运动行为（例如，构架某些东西，用手打招呼，爬梯子）时，90％被定向到患者的动作（相同的平面和方向）。但是，在38％的目标导向行为中没有REM。RBD期间肢体，头部和眼睛运动之间的这种方向性连贯性表明，当存在REM时，REM会模仿梦境的扫描。由于RBD患者和对照组的REM指数和复杂性相似，这种一致性可以扩展到正常的REM睡眠。这些结果与脑干发生器的模型一致，如虚拟现实中那样，它们以协调的并行方式同时激活图像，声音，肢体运动和REM。