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The Lancet. Neurology Oct 2020Dreams are experiences that occur during sleep, while we are disconnected from the environment. Thanks to recent progress in neuroimaging techniques, it is now becoming... (Review)
Review
Dreams are experiences that occur during sleep, while we are disconnected from the environment. Thanks to recent progress in neuroimaging techniques, it is now becoming possible to relate dream features to specific patterns of brain activity. Some conditions occurring in patients with neurological disorders, such as lucid dreams and parasomnias, not only have diagnostic value, but also offer a window into the dream process. They show that dreaming is reflected in physiological signals, behaviours, and brain activity patterns, and that the body can enact dream content. Yet, the dream body can also be distinct from the real body; in their dreams, patients with congenital paraplegia can walk, those with sleep apnoea rarely suffocate, and phantom limb pain can disappear. These conditions provide valuable models for future studies investigating the mechanisms that underlie oneiric experiences.
Topics: Adult; Dreams; Humans; Nervous System Diseases; Sleep; Sleep Stages; Sleep Wake Disorders
PubMed: 32949545
DOI: 10.1016/S1474-4422(20)30275-1 -
Neuroscience Research Apr 2023Dreams are mental experiences, including perceptions, thoughts, and emotions, that occur during sleep. In dreams, hallucinatory perceptions, particularly visual and... (Review)
Review
Dreams are mental experiences, including perceptions, thoughts, and emotions, that occur during sleep. In dreams, hallucinatory perceptions, particularly visual and motoric, are often accompanied by negative emotions. When people dream, they perceive them as real even though they are bizarre and distorted in time and space. People often cannot recall their dreams, even though people dream every night. Dreaming is a strange physiological phenomenon. Research has demonstrated that dreaming is closely associated with rapid eye movement (REM) sleep. It is known that dreaming also occurs during non-REM (NREM) sleep, but the content appears to be different. Dreams during REM sleep tend to be longer, more vivid, more story-like, and more bizarre than those during NREM sleep. In this review, the neural circuits underlying dreaming and the physiological functions associated with it are summarized. Two major theories have been proposed regarding the neural circuits involved in dreaming. One is that dreams are generated by the activation of neural activity in the brainstem and its signal transmission to the cortex. The other is that dreams are caused by forebrain activation by dopamine. Whereas the physiological function of dreams remains unclear, several hypotheses have been proposed that are associated with memory and emotions.
Topics: Humans; Dreams; Sleep; Sleep, REM; Emotions; Mental Recall
PubMed: 36572252
DOI: 10.1016/j.neures.2022.12.017 -
Seminars in Neurology Mar 2005The discovery of the close association between rapid eye movement (REM) sleep and dreaming and development of sleep laboratory techniques ushered in a new era in the... (Review)
Review
The discovery of the close association between rapid eye movement (REM) sleep and dreaming and development of sleep laboratory techniques ushered in a new era in the study of dreams. For the first time, direct and systematic investigation could be made of such topics as the occurrence, qualities, recollection, and childhood development of dreaming. Experimental methodologies permitted investigation of the responsiveness of dreams to external stimulation and the effects of deprivation of REM sleep. Much effort was devoted to searching for parallels between physiological aspects of REM sleep and characteristics of associated dreams, with modest results. The leading theory of dreaming in the early decades of this research was the psychoanalytic, which views dreams as highly meaningful reflections of unconscious mental functioning. With developments in understanding of the neurophysiology of REM sleep, new theories of dreaming were proposed. The most prominent, the activation-synthesis hypothesis, derived its view of dreaming directly from the neurophysiology of REM sleep, in particular the role of the brain stem, and in its original form regarded dreams as not essentially meaningful. Further developments in neurobiological research, including lesion and brain imaging studies, have established a clearer view of the functional neuroanatomy of REM sleep and dreaming. To what degree, and in what way, implications can be drawn from these findings for the psychology of dreaming is controversial. Some more recent theories of dreaming emphasize an adaptive function related to emotion and a role in learning and memory consolidation.
Topics: Dreams; Humans; Sleep Wake Disorders; Sleep, REM
PubMed: 15798942
DOI: 10.1055/s-2005-867078 -
Current Topics in Medicinal Chemistry 2022The sleep-wake cycle is the result of the activity of multiple neurobiological network interactions. The dreaming feature is one interesting sleep on that represents...
The sleep-wake cycle is the result of the activity of multiple neurobiological network interactions. The dreaming feature is one interesting sleep on that represents sensorial components, mostly visual perceptions, accompaniedby intense emotions. Further complexity has been added to the topic of the neurobiological mechanism of dream generation by the current data suggesting drugs' influence on dream generation. Here, we discuss the review of some of the neurobiological mechanisms of the regulation of dream activity, with special emphasis on the effects of stimulants on dreaming.
Topics: Central Nervous System Agents; Dreams; Emotions; Sleep, REM
PubMed: 35761491
DOI: 10.2174/1568026622666220627162032 -
International Journal of... Aug 2013Dreaming occurs during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, which both are regulated by homeostatic, ultradian, and circadian processes.... (Review)
Review
Dreaming occurs during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, which both are regulated by homeostatic, ultradian, and circadian processes. However, the magnitude of how ultradian REM and NREM sleep and its EEG correlates impact onto dream recall remains fairly unknown. In this review, we address three questions: 1. Is there an ultradian NREM-REM sleep modulation in successful dream recall, which is gated by the circadian clock? 2. What are the key electrophysiological correlates that account for dream recall during NREM and REM sleep and 3. Are there age-related changes in the ultradian and circadian regulation in dream recall and its electrophysiological correlates? Knowledge on the specific frequency and topography NREM and REM sleep differences prior to dream recall may pinpoint to the cerebral correlates that account for this cognitive process, and hint to their possible physiological meaning.
Topics: Activity Cycles; Aging; Circadian Rhythm; Dreams; Electroencephalography; Humans; Mental Recall
PubMed: 23524011
DOI: 10.1016/j.ijpsycho.2013.03.006 -
International Review of Neurobiology 2010Individuals differ greatly in their dream recall frequency, in their incidence of recalling types of dreams, such as nightmares, and in the content of their dreams. This... (Review)
Review
Individuals differ greatly in their dream recall frequency, in their incidence of recalling types of dreams, such as nightmares, and in the content of their dreams. This chapter reviews work on the waking life correlates of these differences between people in their experience of dreaming and reviews some of the neurobiological correlates of these individual differences. The chapter concludes that despite there being trait-like aspects of general dream recall and of dream content, very few psychometrically assessed correlates for dream recall frequency and dream content have been found. More successful has been the investigation of correlates of frequency of particular types of dreams, such as nightmares and lucid dreams, and also of how waking-life experience is associated with dream content. There is also potential in establishing neurobiological correlates of individual differences in dream recall and dream content, and recent work on this is reviewed.
Topics: Dreams; Humans; Memory; Sleep; Symbolism; Wakefulness
PubMed: 20870067
DOI: 10.1016/S0074-7742(10)92008-4 -
CNS & Neurological Disorders Drug... 2017Cannabinoids are derivatives that are either compounds occurring naturally in the plant, Cannabis sativa or synthetic analogs of these molecules. The first and most... (Review)
Review
BACKGROUND & OBJECTIVE
Cannabinoids are derivatives that are either compounds occurring naturally in the plant, Cannabis sativa or synthetic analogs of these molecules. The first and most widely investigated of the cannabinoids is Δ9-tetrahydrocannabinol (Δ9-THC), which is the main psychotropic constituent of cannabis and undergoes significant binding to cannabinoid receptors. These cannabinoid receptors are seven-transmembrane receptors that received their name from the fact that they respond to cannabinoid compounds, including Δ9-THC. The cannabinoid receptors have been described in rat, human and mouse brains and they have been named the CB1 and CB2 cannabinoid receptors. Later, an endogenous molecule that exerts pharmacological effects similar to those described by Δ9-THC and binds to the cannabinoid receptors was discovered. This molecule, named anandamide, was the first of five endogenous cannabinoid receptor agonists described to date in the mammalian brain and other tissues. Of these endogenous cannabinoids or endocannabinoids, the most thoroughly investigated to date have been anandamide and 2-arachidonoylglycerol (2-AG). Over the years, a significant number of articles have been published in the field of endogenous cannabinoids, suggesting a modulatory profile in multiple neurobiological roles of endocannabinoids. The general consensus accepts that the endogenous cannabinoid system includes natural ligands (such as anandamide and 2- AG), receptors (CB1 and CB2), and the main enzymes responsible for the hydrolysis of anandamide and 2-AG (fatty acid amide hydrolase [FAAH] and monoacylglycerol lipase [MAGL], respectively) as well as the anandamide membrane transporter (AMT). To date, diverse pieces of evidence have shown that the endocannabinoid system controls multiple functions such as feeding, pain, learning and memory and has been linked with various disturbances, such as Parkinson´s disease. Among the modulatory properties of the endocannabinoid system, current data indicate that the sleep-wake cycle is under the influence of endocannabinoids since the blocking of the CB1 cannabinoid receptor or the pharmacological inhibition of FAAH activity promotes wakefulness, whereas the obstruction of AMT function enhances sleep. However, no solid evidence is available regarding the role of the endocannabinoid system in an unquestionable emotional component of the sleep: Dream activity. Since dreaming is a mental activity that occurs during sleep (characterized by emotions, sensory perceptions, and bizarre components) and the endocannabinoid system modulates neurobiological processes involving consciousness, such as learning and memory, attention, pain perception, emotions and sleep, it is acceptable to hypothesize that the endocannabinoid system might be modulating dream activity. In this regard, an accumulative body of evidence in human and animal models has been reported regarding the role of the endocannabinoid system in the control of emotional states and dreams. Moreover, preliminary studies in humans have indicated that treatment with cannabinoids may decrease post-traumatic stress disorder symptoms, including nightmares.
CONCLUSION
Thus, based on a review of the literature available in PubMed, this article hypothesizes a conceptual framework within which the endocannabinoid system might influence the generation of dream experiences.
Topics: Animals; Consciousness; Dreams; Emotions; Endocannabinoids; Humans
PubMed: 28240187
DOI: 10.2174/1871527316666170223161908 -
Psychiatry Research Oct 2016Although central to any exhaustive theory of human subjectivity, the relationship between dream and waking consciousness remains uncertain. Some findings suggest that...
Although central to any exhaustive theory of human subjectivity, the relationship between dream and waking consciousness remains uncertain. Some findings suggest that dream consciousness can be influenced by severe disorders of thought content. The suppression of unwanted thoughts has been shown to influence dream content in healthy individuals. In order to better define this phenomenon, we evaluated the persistence of obsessive/compulsive themes across the dream and waking cognition of OCD patients and in a control group of healthy subjects. Participants were administered a shortened version of the Thematic Apperception Test to produce a waking fantasy narration, and were trained to keep a dream diary. Dream and waking narrative contents were analyzed in order to recognize obsessive/compulsive themes, and to calculate Mean Dream Obsession/Compulsion (MDO, MDC) and Mean TAT Obsession/Compulsion (MTO, MTC) parameters. No differences were found between the two populations in terms of MDO, MDC, MTO, nor MTC. Density of obsessive and compulsive themes were significantly higher in dream reports than in waking narratives for both groups. No correlation was observed between MDO/MDC scores and Y-BOCS obsession/compulsion scores in the OCD group. These findings strengthen the discontinuity hypothesis, suggesting that ruminative aspects of cognition are somehow interrupted during dream activity.
Topics: Adult; Cognition; Compulsive Behavior; Consciousness; Dreams; Female; Humans; Male; Middle Aged; Obsessive-Compulsive Disorder; Rumination, Cognitive; Thinking
PubMed: 27525832
DOI: 10.1016/j.psychres.2016.08.008 -
Brain Research Bulletin Jun 1998An average person normally spends at least 90 min to 2 h per night dreaming. Nevertheless, memories of dream events are not retrieved while awake unless the person awoke... (Review)
Review
An average person normally spends at least 90 min to 2 h per night dreaming. Nevertheless, memories of dream events are not retrieved while awake unless the person awoke shortly after a dream. It is hypothesized here that schizophrenic delusions initially arise because a system that normally inhibits the formation of memories of dream events is defective. Therefore, memories of dream events or fragments would be occasionally made and placed in the normal memory store. The only reason that we really know anything happened to us in the past is that we have a memory of it, and having a memory of an event is sufficient to really believe it. Therefore, the schizophrenic would believe that the dream events actually happened. It is proposed that this is the basis of primary delusions. Because memories are represented by strengthened neural connections there will be an accumulation of connections that do not correspond to reality. This accumulation may account for other symptoms of schizophrenia such as thought disorder, loosening of associations, and hallucinations. The brain trying to draw conclusions from several memories may be the basis of secondary delusions. Evidence is presented for the ideas that primary delusions are due to memories of dream events, that a substance, with vasotocin-like bioactivity, is released in the brain during dreaming and inhibits memory formation, that the lateral habenula is a brain area involved in vasotocin actions and is affected by neuroleptics, and that brain mechanisms involved in vasotocin actions show pathological alterations in schizophrenia.
Topics: Delusions; Disease Progression; Dreams; Humans; Inhibition, Psychological; Memory; Models, Psychological; Schizophrenia; Schizophrenic Psychology
PubMed: 9667811
DOI: 10.1016/s0361-9230(98)00011-2 -
The Journal of the American Academy of... 2002There is great interest in brain function as a result of the new laboratory and imaging techniques in the neurosciences. Psychoanalysis has embraced these contributions... (Review)
Review
There is great interest in brain function as a result of the new laboratory and imaging techniques in the neurosciences. Psychoanalysis has embraced these contributions without adequate assessment of whether they bridge the mind/brain divide and provide answers to the questions psychoanalysts ask. A review and critique of the biological theories of dreaming highlights their limitations and points out they do not address the semantics, meaning, and content of dreaming nor the pragmatics of dreaming, its function. At best these theories attempt to provide the syntax of dreaming, the form dreaming takes. Brain biology cannot provide the transduction rules to go from neuronal firing to the psychological experience of dreaming or other mind states.
Topics: Brain; Diagnostic Imaging; Dreams; Humans; Mind-Body Relations, Metaphysical; Neurons; Psychoanalytic Interpretation; Psychoanalytic Theory; Synaptic Transmission
PubMed: 12597109
DOI: 10.1521/jaap.30.4.657.24187