Rapid Eye Movements (REMs) and visual dream recall in both congenitally blind and sighted subjects

Abstract

Our objective was to evaluate rapid eye movements (REMs) associated with visual dream recall in sighted subjects and congenital blind. During two consecutive nights polysomnographic recordings were performed at subjects home. REMs were detected by visual inspection on both EOG channels (EOG-H, EOG-V) and further classified as occurring isolated or in bursts. Dream recall was defined by the existence of a dream report. The two groups were compared using t-test and also the two-way ANOVA and a post-hoc Fisher test (for the features diagnosis (blind vs. sighted) and dream recall (yes or no) as a function of time). The average of REM awakenings per subject and the recall ability were identical in both groups. CB had a lower REM density than CS; the same applied to REM bursts and isolated eye movements. In the two-way ANOVA, REM bursts and REM density were significantly different for positive dream recall, mainly for the CB group and for diagnosis; furthermore for both features significant results were obtained for the interaction of time, recall and diagnosis; the interaction of recall and time was however, stronger. In line with previous findings the data show that blind have lower REMs density. However the ability of dream recall in congenitally blind and sighted controls is identical. In both groups visual dream recall is associated with an increase in REM bursts and density. REM bursts also show differences in the temporal profile. REM visual dream recall is associated with increased REMs activity. 3,4,5,6,7,8 . Keywords Dream recallThe study of dreams is closely related to the ability to recall them. There are different methods to study the capacity for dream recall: the morning recall by means of brief questionnaires or dream diaries or the recall after dream interruption. Both methods, if applied to frequent dreamers, revealed consistent results 9,10 . However, this consistency does not occur in infrequent dreamers, for whom the capacity for recall is greater in provoked awakenings 10 . , although it does increase with interest, motivation, moodiness and stress 14. The capacity for dream recall is also slightly higher in women.The content of dream recall varies throughout the night. At the beginning of the night daily residues, related to every day's activity predominate, whereas later in the night hallucinatory or complex character narrative is more frequent 11 . Oneiric dream contentRecall is also positively related to the vivacity, bizarreness and emotional content of dreams, which in turn are influenced by the oneiric visual content 15 .In fact, the richness and continuity of the visual content increases the capacity for spontaneous recall 16 . For these reasons the recall/visual content binomial assumes a particular relevance in the dreams of blind subjects. The works that consider that blind subjects do not have visual dream contents 17 , were contradicted by several studies, namely by one from our group 18 , which demonstrated that blind people do have the ability to draw their own dreams and,...

Mental Imagery in Dreams of Congenitally Blind People

“…Our report of oneiric visual-like imagery in congenitally blind subjects (Figure 1; Table 3), however, challenges the negative findings in the majority of previous studies [16,17]. On the other hand, our results appear to be in keeping with two studies that have demonstrated (oneiric) visual-like imagery in congenitally and totally blind subjects lacking any previous visual perception or experience [17,41,43].…”

“…Nonetheless, over the years, it has been reported that congenitally blind people can, and do, experience oneiric visuo-spatial imagery in a way that is similar to sighted individuals [5,[41][42][43]. In keeping with this, significant negative correlations between the visual activity index (defined by performing a quantitative analysis of dream content, also see [42]) and occipital alpha power have been demonstrated during REM's dream mentation in congenitally blind subjects [43].…”

The Defensive Activation Theory: REM Sleep as a Mechanism to Prevent Takeover of the Visual Cortex

“…Because the circuitry for REM sleep presumably evolved over tens of millions of years, it is unaffected by our modern ability to defy darkness with electrical light. It thus comes as no surprise that people born blind retain the same PGO circuitry as the sighted (Bértolo et al, 2017), and they dream. However, note that the congenitally-and early blind experience no visual imagery in their dreams but do have other sensory The correlation is significant for both measures.…”

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“…More recent work (Ilic et al, 2023) continues to support that "mental representation of images may not be entirely dependent on visual input" (2023, p. 2). Dream researchers Bértolo et al (2017) concluded based on EEG measurements on dreaming congenitally blind individuals that such persons "are able to generate visual imagery without visual experience" (2017, p. 8). Before such studies, one would always be tempted to say, "They just learned it," because our innate organization tends to be overshadowed by our extensive learning capacities.…”