Topography of the lambda-like response in rapid eye movement sleep: A current source-density analysis

Abstract

Lambda response (P1 and P2) reflects visual information processing after saccades in wakefulness. Similar potentials also occur after rapid eye movements (REMs) in REM sleep. In this study, current source density (CSD) maps of these potentials were compared. Sixteen healthy, young volunteers participated in the wake and sleep sessions. Saccades were recorded during a self‐paced visual search task, and REMs were recorded during natural nocturnal sleep. The P1 showed a focus of CSD at the occipital site (Oz) in wakefulness but at the parieto‐occipital site (POz) in REM sleep. The P2 had a CSD focus at POz in both states. These results suggest the cortical sources of the P1 after rapid eye movements differ between REM sleep and wakefulness.

Cortical regions activated after rapid eye movements during REM sleep

“…[16][17][18] Previous studies have shown that rapid eye movements during REM sleep elicit similar brain potentials, called lambda-like response, without visual input from the retina. [19][20][21][22][23] This finding suggests that a kind of visual information processing may occur during REM sleep, as is found during wakefulness. In comparison to lambda response that occur during wakefulness, it is also known that the lambda-like responses occur more often in the parietal region (parietal-occipital site).…”

“…The lambda response is assumed to correspond to visual evoked potentials after fixation 16–18 . Previous studies have shown that rapid eye movements during REM sleep elicit similar brain potentials, called lambda‐like response, without visual input from the retina 19–23 . This finding suggests that a kind of visual information processing may occur during REM sleep, as is found during wakefulness.…”

“…This finding suggests that a kind of visual information processing may occur during REM sleep, as is found during wakefulness. In comparison to lambda response that occur during wakefulness, it is also known that the lambda‐like responses occur more often in the parietal region (parietal‐occipital site) 22,23 …”

A new view of “dream enactment” in REM sleep behavior disorder

“…Additional support for this perspective comes from studies of cortical electroencephalogram (EEG) activity in relation to wake-related eye movements (i.e., saccades) and REMs in human adults [47,48]. For example, in recordings from parieto-occipital cortex [47], wake-related saccades were immediately preceded by a so-called readiness potential (“presaccadic negativity”). In contrast, no such potential was observed immediately preceding REMs, suggesting that REMs are not generated in response to activity in visual cortex.…”

“…Also, contrary to the widespread assumption that sleep entails isolation from sensory input (see Figure 1), the cerebral cortex during REM sleep is activated in response to limb and eye movements. Evidence for reafferent activation is clear in infant rats with respect to limb and whisker twitches [25,33,54,56] and in premature human infants with respect to hand twitches [62], and is suggestive in human adults with respect to REMs [47–49]. But again, in contrast with copious evidence detailing the role of the brainstem in the generation of twitches [30,32,38,40,41], there is no such evidence detailing a similar role for motor cortex.…”