fMRI evidence for multisensory recruitment associated with rapid eye movements during sleep

Abstract

We studied the neural correlates of rapid eye movement during sleep (REM) by timing REMs from video recording and using rapid event-related functional MRI. Consistent with the hypothesis that REMs share the brain systems and mechanisms with waking eye movements and are visually-targeted saccades, we found REM-locked activation in the primary visual cortex, thalamic reticular nucleus (TRN), ‘visual claustrum’, retrosplenial cortex (RSC, only on the right hemisphere), fusiform gyrus, anterior cingulate cortex, and the oculomotor circuit that controls awake saccadic eye movements (and subserves awake visuospatial attention). Unexpectedly, robust activation also occurred in non-visual sensory cortices, motor cortex, language areas, and the ascending reticular activating system, including basal forebrain, the major source of cholinergic input to the entire cortex. REM-associated activation of these areas, especially non-visual primary sensory cortices, TRN and claustrum, parallels findings from waking studies on the interactions between multiple sensory data, and their ‘binding’ into a unified percept, suggesting that these mechanisms are also shared in waking and dreaming and that the sharing goes beyond the expected visual scanning mechanisms. Surprisingly, REMs were associated with a decrease in signal in specific periventricular subregions, matching the distribution of the serotonergic supraependymal plexus. REMs might serve as a useful task-free probe into major brain systems for functional brain imaging.

Activation of Retinotopic Visual Areas Is Central to REM Sleep Associated Dreams: Visual Dreams and Visual Imagery Possibly Co-Emerged In Evolution

“…However, REMS visual imagery uses very similar neural systems as those used in wakefulness (Borst, & Kosslyn, 2010Sprenger et al, 2010. Nevertheless, recent event-related fMRI showed activation of V1 during REMS (Hong et al, 2009Miyauchi et al, 2009) and the findings that REMS associated visual imagery uses very similar neural systems as those used in wakefulness (Nir & Tononi, 2010Sprenger et al, 2010 support our contention.…”

“…Recently, Hong et al (2009) confirmed the REM-locked activation in the striate cortices. According to Hong et al (2009) (Kosslyn, 1994, p. 75).…”

“…According to Hong et al (2009) (Kosslyn, 1994, p. 75). Accordingly, dreaming is conceptualized as `internally generated images which are fed backwards into the cortex as if they were coming from the outside' (Zeki, 1993, p.…”

“…However, complex retinotopic visual can serve some special function not only during visual perception and imagery but also during REMS associated visual dreams. Since, it appears that numerous retinotopic visual areas are activated during REMS (Igawa et al, 2001Peigneux et al, 2001Hong et al, 2009Miyauchi et al, 2009, it suggests that one of the major aims of REMS is to activate visual imagery directed via subconscious processes. Based on present knowledge, the neuro-anatomo-chemical substrates in the brain for activation of REMS-associated expression of visual imagery may be supported by the diagram shown in Figure 1a and 1b.…”

“…The authors suggested that this can play a role in cognitive processes associated to REMS at least in humans. Recent findings from fMRI experiments proved that not only extrastriate but also primary visual cortex (V1) can be activated in relation to REMS (Hong et al, 2009Miyauchi et al, 2009). In addition, Muckli (2010) based on latest fMRI findings suggested that V1 can be involved in higher cognitive functions.…”