Coming to grips with a "new" state of consciousness: the study of rapid-eye-movement sleep in the 1960s

The recognition of rapid-eye-movement sleep (REM) and its association with dreaming in 1953 by Aserinsky and Kleitman opened a new world to explore in the brain. Discussions at two major symposia in the early 1960s reveal that a state with characteristics resembling both wakefulness and sleep was overturning accepted views of the regulation of the two states. Participants grappled with the idea that cortical activation could occur during sleep. They struggled with picking a name that would capture the essence of REM without focusing on just one aspect of the state. Questioning whether REM in cats could be homologous with that of humans suggested an anthropocentric focus on human dreaming as the essence of the state. The need for biochemical studies was evident given that deprivation of REM caused a rebound in the amount of subsequent REM, which indicated that simple synaptic activity could not support this phenomenon.

Rhythmic alternating patterns of brain activity distinguish rapid eye movement sleep from other states of consciousness

Rapid eye movement (REM) sleep constitutes a distinct "third state" of consciousness, during which levels of brain activity are commensurate with wakefulness, but conscious awareness is radically transformed. To characterize the temporal and spatial features of this paradoxical state, we examined functional interactions between brain regions using fMRI resting-state connectivity methods. Supporting the view that the functional integrity of the default mode network (DMN) reflects "level of consciousness," we observed functional uncoupling of the DMN during deep sleep and recoupling during REM sleep (similar to wakefulness). However, unlike either deep sleep or wakefulness, REM was characterized by a more widespread, temporally dynamic interaction between two major brain systems: unimodal sensorimotor areas and the higher-order association cortices (including the DMN), which normally regulate their activity. During REM, these two systems become anticorrelated and fluctuate rhythmically, in reciprocally alternating multisecond epochs with a frequency ranging from 0.1 to 0.01 Hz. This unique spatiotemporal pattern suggests a model for REM sleep that may be consistent with its role in dream formation and memory consolidation.

[Neuropsychology of dreams]

INTRODUCTION

Dreams are a universal human experience and studying them from the point of view of neuroscience, consciousness, emotions and cognition is quite a challenge for researchers. Thus, dreams have been addressed from a number of different perspectives ranging from philosophy to clinical medicine, as well as psychiatry, psychology, artificial intelligence, neural network models, psychophysiology or neurobiology.

DEVELOPMENT

The main models are grounded on the biological function of dreams, especially those based on processes involving the consolidation of memory and forgetting, and models of simulation. Similarly, current models are developed upon the neurobiology and the neuropsychology of the REM phases of sleep and how they are differentiated from wakefulness. Thus, neurobiologically speaking, dreams are related to the role of acetylcholine and, neuropsychologically, to the activation of the limbic and paralimbic regions, the activation of the basal ganglia, the activation of cortical areas with a specific modality (especially Brodmann's areas 19, 22 and 37) and the deactivation of the ventromedial, parietal and dorsolateral prefrontal cortex and posterior cingulate.

CONCLUSIONS

Dreams can be considered a state of consciousness that is characterised by a reduced control over their content, visual images and activation of the memory, and which is mediated by motivational incentives and emotional salience.

Neural correlates of dream lucidity obtained from contrasting lucid versus non-lucid REM sleep: a combined EEG/fMRI case study

STUDY OBJECTIVES

To investigate the neural correlates of lucid dreaming.

DESIGN

Parallel EEG/fMRI recordings of night sleep.

SETTING

Sleep laboratory and fMRI facilities.

PARTICIPANTS

Four experienced lucid dreamers.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Out of 4 participants, one subject had 2 episodes of verified lucid REM sleep of sufficient length to be analyzed by fMRI. During lucid dreaming the bilateral precuneus, cuneus, parietal lobules, and prefrontal and occipito-temporal cortices activated strongly as compared with non-lucid REM sleep.

CONCLUSIONS

In line with recent EEG data, lucid dreaming was associated with a reactivation of areas which are normally deactivated during REM sleep. This pattern of activity can explain the recovery of reflective cognitive capabilities that are the hallmark of lucid dreaming.

The roles of the reward system in sleep and dreaming

The mesolimbic dopaminergic system (ML-DA) allows adapted interactions with the environment and is therefore of critical significance for the individual's survival. The ML-DA system is implicated in reward and emotional functions, and it is perturbed in schizophrenia, addiction, and depression. The ML-DA reward system is not only recruited during wakeful behaviors, it is also active during sleep. Here, we introduce the Reward Activation Model (RAM) for sleep and dreaming, according to which activation of the ML-DA reward system during sleep contributes to memory processes, to the regulation of rapid-eye movement (REM) sleep, and to the generation and motivational content of dreams. In particular, the engagement of ML-DA and associated limbic structures prioritizes information with high emotional or motivational relevance for (re)processing during sleep and dreaming. The RAM provides testable predictions and has clinical implications for our understanding of the pathogenesis of major depression and addiction.

Unresponsiveness ≠ unconsciousness

Consciousness is subjective experience. During both sleep and anesthesia, consciousness is common, evidenced by dreaming. A defining feature of dreaming is that, while conscious, we do not experience our environment; we are disconnected. Besides inducing behavioral unresponsiveness, a key goal of anesthesia is to prevent the experience of surgery (connected consciousness), by inducing either unconsciousness or disconnection of consciousness from the environment. Review of the isolated forearm technique demonstrates that consciousness, connectedness, and responsiveness uncouple during anesthesia; in clinical conditions, a median 37% of patients demonstrate connected consciousness. We describe potential neurobiological constructs that can explain this phenomenon: during light anesthesia the subcortical mechanisms subserving spontaneous behavioral responsiveness are disabled but information integration within the corticothalamic network continues to produce consciousness, and unperturbed norepinephrinergic signaling maintains connectedness. These concepts emphasize the need for developing anesthetic regimens and depth of anesthesia monitors that specifically target mechanisms of consciousness, connectedness, and responsiveness.

Assessing the dream-lag effect for REM and NREM stage 2 dreams

This study investigates evidence, from dream reports, for memory consolidation during sleep. It is well-known that events and memories from waking life can be incorporated into dreams. These incorporations can be a literal replication of what occurred in waking life, or, more often, they can be partial or indirect. Two types of temporal relationship have been found to characterize the time of occurrence of a daytime event and the reappearance or incorporation of its features in a dream. These temporal relationships are referred to as the day-residue or immediate incorporation effect, where there is the reappearance of features from events occurring on the immediately preceding day, and the dream-lag effect, where there is the reappearance of features from events occurring 5–7 days prior to the dream. Previous work on the dream-lag effect has used spontaneous home recalled dream reports, which can be from Rapid Eye Movement Sleep (REM) and from non-Rapid Eye Movement Sleep (NREM). This study addresses whether the dream-lag effect occurs only for REM sleep dreams, or for both REM and NREM stage 2 (N2) dreams. 20 participants kept a daily diary for over a week before sleeping in the sleep laboratory for 2 nights. REM and N2 dreams collected in the laboratory were transcribed and each participant rated the level of correspondence between every dream report and every diary record. The dream-lag effect was found for REM but not N2 dreams. Further analysis indicated that this result was not due to N2 dream reports being shorter, in terms of number of words, than the REM dream reports. These results provide evidence for a 7-day sleep-dependent non-linear memory consolidation process that is specific to REM sleep, and accord with proposals for the importance of REM sleep to emotional memory consolidation.

[Phenomenology of dreams]

A phenomenology of dreams searches for meaning, with the aim not only of explaining but also of understanding the experience. What and who is it for? And what about the nearly forgotten dream among the moderns, the banal returning to the nightmare, sleepiness, or dreamlike reverie. Nostalgia for the dream, where we saw a very early state of light, not a ordinaire qu duel. Regret for the dreamlike splendor exceeded by the modeling power of modern aesthetics--film and the explosion of virtual imaging technologies. Disappointment at the discovery of a cognitive permanence throughout sleep and a unique fit with the real upon awaking? An excess of methodological rigor where we validate the logic of the dream, correlating the clinical improvement in psychotherapy and the ability to interpret one's own dreams. The dangerous psychological access when the dream primarily is mine, viewed as a veiled expression of an unspoken desire, or when the dream reveals to me, in an existential conception of man, through time and space, my daily life, my freedom beyond my needs. Might its ultimate sense also mean its abolition? From the story of a famous forgotten dream, based on unexpected scientific data emerges the question: do we dream to forget? The main thing would not be consciousness but confidence, when " the sleeping man, his regard extinguished, dead to himself seizes the light in the night " (Heraclitus).

To what extent do neurobiological sleep-waking processes support psychoanalysis?

Sigmund Freud's thesis was that there is a censorship during waking that prevents memory of events, drives, wishes, and feelings from entering the consciousness because they would induce anxiety due to their emotional or ethical unacceptability. During dreaming, because the efficiency of censorship is decreased, latent thought contents can, after dream-work involving condensation and displacement, enter the dreamer's consciousness under the figurative form of manifest content. The quasi-closed dogma of psychoanalytic theory as related to unconscious processes is beginning to find neurobiological confirmation during waking. Indeed, there are active processes that suppress (repress) unwanted memories from entering consciousness. In contrast, it is more difficult to find neurobiological evidence supporting an organized dream-work that would induce meaningful symbolic content, since dream mentation most often only shows psychotic-like activities.

Hallucinations in narcolepsy with and without cataplexy: contrasts with Parkinson's disease

BACKGROUND

Narcolepsy and Parkinson's disease (PD) are associated with hallucinations, excessive daytime sleepiness, REM sleep behavior disorder (RBD), as well as complete (narcolepsy with cataplexy) vs. partial (PD, narcolepsy without cataplexy) hypocretin-1 deficiency.

OBJECTIVE

To compare the hallucinations associated with narcolepsy to those of PD.

METHODS

One hundred patients with narcolepsy (with and without cataplexy) and 100 patients with PD were consecutively interviewed about their hallucinations (frequency, phenomenology, insight into unreality and association with sleep) as well as their risk factors.

RESULTS

Hallucinations occurred more frequently and with more motor and multimodal aspects in narcolepsy with cataplexy (59%) than in narcolepsy without cataplexy (28%) and PD (26%). Compared to PD, the hallucinations in narcolepsy were less frequently of the passage/presence type (passage: brief visions of a person or animal passing sideways; presence: perception that a living character or an animal is behind or near the subject, without the subject actually seeing, hearing or touching it), more frequently auditory and more often associated with sleep. However, in 40% of the patients with narcolepsy and 54% of the patients with PD, the hallucinations occurred while the patients were wide awake. Patients with cataplexy had reduced immediate insight into the unreality of their hallucinations compared to patients with PD, but the delusions were exceptional (2%), transient and based on hallucinations in both groups. The risk factors for hallucinations were sleep paralysis and RBD in narcolepsy and motor disability and sleepiness in PD.

CONCLUSIONS

The multimodal, dreamlike aspect of hallucinations in narcolepsy with cataplexy could transiently impair the patients' insight. The high frequency of these hallucinations (compared to those in narcolepsy without cataplexy or PD) suggests that complete (more than partial) hypocretin-1 deficiency promotes hallucinations.

The dreaming brain/mind, consciousness and psychosis

Several independent lines of research in neurobiology seem to support the phenomenologically-grounded view of the dreaming brain/mind as a useful model for psychosis. Hallucinatory phenomena and thought disorders found in psychosis share several peculiarities with dreaming, where internally generated, vivid sensorimotor imagery along with often heightened and incongruous emotion are paired with a decrease in ego functions which ultimately leads to a severe impairment in reality testing. Contemporary conceptualizations of severe mental disorders view psychosis as one psychopathological dimension that may be found across several diagnostic categories. Some experimental data have shown cognitive bizarreness to be equally elevated in dreams and in the waking cognition of acutely psychotic subjects and in patients treated with pro-dopaminergic drugs, independent of the underlying disorder. Further studies into the neurofunctional underpinnings of both conditions will help to clarify the use and validity of this model.

Evolution and epilepsy in "Bleak House"

In Charles Dickens's novels, nervous seizures trigger dreamy, clairvoyant episodes in which normally imperceptible connections and relations among events and characters come to light. During such episodes, which the neurologist John Hughlings Jackson would describe as "voluminous" states of consciousness, the boundaries of the self dissolve, and the mind becomes attuned to a range of possible identities or phantom selves. The specters unleashed in this state of nervous "dissolution" haunt Bleak House even as they illuminate relations among members of vastly different social worlds and the great institutional forces that affect the most curious events of the mind.

[Is it still the "royal way"? The dream as a junction of neurobiology and psychoanalysis]

Some decades ago the dream seemed to be randomly generated by brain stem mechanisms in the cortical and subcortical neuronal networks. However, most recent empirical data, studies on brain lesions and functional neuroimaging results have refuted this theory. Several data support that motivation pathways, memory systems, especially implicit, emotional memory play an important role in dream formation. This essay reviews how the results of neurobiology and cognitive psychology can be fitted into the theoretical frameworks and clinical practice of the psychoanalysis. The main aim is to demonstrate that results of neurobiology and empirical observations of psychoanalysis are complementary rather than contradictory.

Between passion and repression: medical views of demon dreams, demonic fetuses, and female sexual madness in late imperial China

This article argues that early Chinese physicians had already related female ailments to their sexual frustration. Moreover, many physicians paid more attention to non-reproductive women – nuns, widows, and unmarried women – as if they were more prone to suffer from unfulfilled desires and sexual frustration and, as a result, produce the sexual dreams and monstrous births that were described in the medical literature of medieval China as physical ailments. The earlier body-oriented etiology of these female illnesses gradually shifted to emotion-oriented perspectives in late imperial China. In particular, the sixteenth- and seventeenth-century doctors began to categorize women's sexual frustration as "yu disorders" or "love madness." In this article I will show not only the changing medical views of female sexual madness throughout the ages, but how these views were shaped by the societies in which both the doctors and patients were situated.

Strengths and weaknesses of McNamara's evolutionary psychological model of dreaming

This article includes a brief overview of McNamara's (2004) evolutionary model of dreaming. The strengths and weaknesses of this model are then evaluated in terms of its consonance with measurable neurological and biological properties of dreaming, its fit within the tenets of evolutionary theories of dreams, and its alignment with evolutionary concepts of cooperation and spirituality. McNamara's model focuses primarily on dreaming that occurs during rapid eye movement (REM) sleep; therefore this article also focuses on REM dreaming.

Lucid dreaming and ventromedial versus dorsolateral prefrontal task performance

Activity in the prefrontal cortex may distinguish the meta-awareness experienced during lucid dreams from its absence in normal dreams. To examine a possible relationship between dream lucidity and prefrontal task performance, we carried out a prospective study in 28 high school students. Participants performed the Wisconsin Card Sort and Iowa Gambling tasks, then for 1 week kept dream journals and reported sleep quality and lucidity-related dream characteristics. Participants who exhibited a greater degree of lucidity performed significantly better on the task that engages the ventromedial prefrontal cortex (the Iowa Gambling Task), but degree of lucidity achieved did not distinguish performance on the task that engages the dorsolateral prefrontal cortex (the Wisconsin Card Sort Task), nor did it distinguish self-reported sleep quality or baseline characteristics. The association between performance on the Iowa Gambling Task and lucidity suggests a connection between lucid dreaming and ventromedial prefrontal function.

The underlying emotion and the dream relating dream imagery to the dreamer's underlying emotion can help elucidate the nature of dreaming

There is a widespread consensus that emotion is important in dreams, deriving from both biological and psychological studies. However, the emphasis on examining emotions explicitly mentioned in dreams is misplaced. The dream is basically made of imagery. The focus of our group has been on relating the dream imagery to the dreamer's underlying emotion. What is most important is the underlying emotion--the emotion of the dreamer, not the emotion in the dream. This chapter discusses many studies relating the dream-especially the central image of the dream--to the dreamer's underlying emotion. Focusing on the underlying emotion leads to a coherent and testable view of the nature of dreaming. It also helps to clarify some important puzzling features of the literature on dreams, such as why the clinical literature is different in so many ways from the experimental literature, especially the laboratory-based experimental literature. Based on central image intensity and the associated underlying emotion, we can identify a hierarchy of dreams, from the highest-intensity, "big dreams," to the lowest-intensity dreams from laboratory awakenings.

Karl Abraham in New York: the contributions of Bertram D. Lewin

Bertram D. Lewin (1896-1971), a leading member of the New York Psychoanalytic Society and Institute, trained at the Berlin Psychoanalytic Institute in the late 1920s. Lewin's thinking was deeply influenced by Karl Abraham, whose delineation of the oral stage of libidinal development provided the theoretical foundation for Lewin's highly original psychoanalytic papers on mania, sleep and dreams. These contributions and his articulation of the oral triad -- the wish to eat, the wish to be eaten and the wish to sleep -- are reviewed and the stimulating influence his thinking exercised on his analytic colleagues is noted.