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Journal: Dreaming

Technology opens up new ways to observe the dreaming brain.

❶Dream reporting following abrupt and gradual awakenings from different types of sleep. The dreams may reflect what we are worried about, or problems that we wish to solve.

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Second, an interest in dreams or a positive attitude toward dreams clearly covaries with DRF Hill et al. Third, several cognitive abilities have been found to covary with DRF. Contradictory results have been reported for the correlation between DRF and memory abilities short-term, long-term, visual, verbal, implicit, and explicit; significant positive correlation: Cory and Ormiston, ; Belicki et al. Cohen, ; Belicki et al. Hiscock and Cohen, ; Richardson, ; Okada et al.

However, several studies have consistently shown that DRF is positively correlated with creativity Fitch and Armitage, ; Schredl, ; Schredl et al. Finally, many authors have reported a correlation between DRF and personality traits.

Subjects with a high DRF are more likely to have a personality with thinner boundaries Hartmann described people with thin boundaries as being open, trustworthy, vulnerable, and sensitive; Hartmann, ; Hartmann et al. However, those results have not always been reproducible e. In conclusion, numerous parameters have been identified that covary with DRF. Schredl stressed in many of his papers that the studied parameters usually explain only a small percentage of the total variance e.

Thus, the DRF variation profile suggests that the production, encoding and recall of dreams are influenced by numerous parameters that probably interact with each other. The neuroscientific approach to dreaming arose at the end of the s with the discovery of REM during human sleep by the American physiologist Nathaniel Kleitman and his team Aserinsky and Kleitman, ; Dement and Kleitman, a. During these sleep episodes with saccades, the researchers noticed a decrease in voltage and an increase in frequency in the EEG, accompanied by an increase in cardiac frequency variability and a decrease in body movements.

They concluded that these physiological modifications indicate a particular sleep stage, which they called REM sleep. Several years later, Fisher et al. Researchers concluded that dreaming occurs during REM sleep. The eye movements of REM sleep would allow the dreamer to scan the imaginary scene of the dream the scanning hypothesis ; the cerebral cortex activation revealed by the rapid EEG would allow intense cognitive activity, creating the complex stories of a dream; and the lack of muscle tone would prevent the dreamer from acting out his dreams.

From that time on, researchers investigated REM sleep to obtain answers about dreaming. In the s, researchers used functional neuroimaging techniques such as positron emission tomography PET to investigate brain activity during REM sleep in humans. This new approach enabled researchers to demonstrate that the functional organization of the brain during REM sleep is different from the functional organization of the brain during wakefulness Maquet et al.

In comparison to wakefulness, brain activity during REM sleep is decreased in some brain regions e. Looking more generally for brain activity correlating with REM sleep the vigilance states considered included wakefulness, slow-wave sleep, and REM sleep , Maquet et al. Based on these results, researchers argued that the particular functional organization of the brain during REM sleep could explain the phenomenological characteristics of dream reports Hobson and Pace-Schott, ; Schwartz and Maquet, ; Maquet et al.

They considered that brain activity increases and decreases during REM sleep could be interpreted on the basis of what we know about brain activity during wakefulness. In this context, the increased occipital cortex activity during REM sleep could explain the visual component of dream reports because neuroimaging results during wakefulness showed that visual imagery with the eyes closed activates the occipital cortex Kosslyn and Thompson, The decreased activity in the temporoparietal junction during REM sleep may explain why dreams are mainly experienced in the egocentric coordinates of the first-person; indeed, during wakefulness, activity in the temporoparietal junction was reported to be greater for allocentric vs.

The increased activity in the hippocampus during REM sleep could explain why dreams are often composed of known images or characters, as the hippocampus is known to be associated with the encoding and retrieval of lived events during wakefulness e. Indeed, during wakefulness, the lateral prefrontal cortex is involved in executive function, cognitive control, and working memory Petrides, ; Koechlin and Hyafil, The increased activity in the medial prefrontal cortex during REM sleep could explain the attribution of thoughts, beliefs, and emotions to the characters in the dream because, during wakefulness, the medial prefrontal cortex is known to participate in mind reading Ruby et al.

In conclusion, results from experimental psychology and neuroscience allow us to better understand the phenomenology of dreaming and the cerebral correlates of some characteristics of dream reports.

Still, what do they tell us about the role of dreaming? What are the current hypotheses about dream function s? At the end of the twentieth century, the neurologist Alan Hobson, who was profoundly anti-psychoanalysis, proposed a theory that deprived dreaming of any function. Hobson argued that dreaming is an epiphenomenon of REM sleep: This lesion resulted in the appearance of movements during REM sleep. Movies from the Jouvet lab show sleeping cats performing complex motor actions with altered control and coordination resembling those of wakefulness, such as fur licking, growling, chasing prey, mastication, and fighting.

Later in his career, Jouvet moved toward a hypothesis focusing on the role of dreaming in the individual dimension. We thus have to explain how certain aspects of psychological heredity found in homozygote twins raised in different surroundings may persist for a whole life psychological individuation. A definitive genetic programming during development by neurogenesis is unlikely due to the plasticity of the nervous system.

That is why we have to consider the possibility of an iterative genetic programming. The internal mechanisms synchronous of paradoxical sleep SP are particularly adapted to such programming. This would activate an endogenous system of stimulation that would stimulate and stabilize receptors genetically programmed by DNA in some neuronal circuits.

The excitation of these neurons during SP leads to oniric behaviors that could be experimentally revealed — the lists of these behaviors are specific to each individual and indirect data suggest a genetic component of this programming. Amongst the mechanisms allowing the iterative programming of SP, sleep is particularly important. Security — and hence the inhibition of the arousal system — is a sine qua non-condition for genetic programming to take place. This process would ensure the stability of personality across time.

The Finnish psychologist Antti Revonsuo recently proposed a hypothesis called threat simulation theory, which explains the fearful characteristics of dream content Revonsuo, ; Valli and Revonsuo, According to this theory, dreams serve as virtual training places to improve threat avoidance or threat fighting ability.

The theory postulates that such nocturnal training makes the dreamer more efficient at resolving threatening situations during wakefulness. Her team showed that, in healthy subjects, the depression level before sleep was significantly correlated with affect in the first REM report.

Her team also observed that low scorers on the depression scale displayed a flat distribution of positive and negative affect in dreams, whereas those with a depressed mood before sleep showed a pattern of decreasing negative and increasing positive affect in dreams reported from successive REM periods Cartwright et al. The researchers concluded that negative dreams early in the night may reflect a within-sleep mood regulation process, whereas those that occur later may indicate a failure in the completion of this process.

Finally, a current mainstream hypothesis in cognitive neuroscience credits sleep and dreaming with a role in memory consolidation for a recent review, see Diekelmann and Born, Numerous studies have shown that brain activity during training is replayed during post-training sleep e.

Decreased performance during the post-training day in sleep-deprived subjects further suggested that the replay of brain activity at night contributes to memory consolidation e. Only recently, however, have experimental results in humans argued in favor of a role of dreaming per se in memory consolidation.

In one study, subjects were trained on a virtual navigation task before taking a nap. Post-nap tests showed that subjects who dreamed about the task performed better than subjects who did not dream note that only 4 out of 50 subjects dreamed about the task in this study; Wamsley et al. Using a different approach, Nielsen and colleagues provided additional arguments supporting a link between dreams and memory Nielsen et al.

The similarity between the delay of episodic event incorporation into dreams and the delay of post-training cellular plasticity in the hippocampus led the Canadian team to suggest a link between dreaming and episodic memory consolidation.

In summary, the preceding section describes the current state of the art on dreaming, its phenomenology and cerebral correlates and hypotheses about its functions.

Some substantial advances have been made, but much remains to be understood. A piece of evidence in favor of a strong link between REM sleep and dreaming is the oneiric behavior the appearance of complex motor behaviors when motor inhibition is suppressed during REM sleep discovered by Sastre and Jouvet in cats and reproduced by Sanford et al. Researchers interpreted these results as the animal acting out its dream.

However, as animals do not talk, the link between oneiric behavior and dream recall cannot be tested experimentally.

This limitation seriously hampers our understanding of dreaming. In humans, complex motor behaviors e. It can be caused by substance withdrawal e. According to physicians experts on this syndrome, some patients report dreams that are consistent with their behaviors in REM sleep Mahowald and Schenck, According to the literature, however, such matches seem to be loose and not systematic. Only one study has tested whether observers can link dream content to sleep behaviors in RBD Valli et al.

In this study, each video recording of motor manifestations was combined with four dream reports, and seven judges had to match the video clip with the correctly reported dream content. The authors found that reported dream content can be linked to motor behaviors at a level better than chance. Note, however, that because the authors obtained only movements and not behavioral episodes for many RBD patients, the link between videos and dream reports was unfairly difficult to make.

It is important to note that motor behavior during sleep can happen outside of REM sleep. Sleepwalking and sleep terrors, which occur during NREM sleep, are usually not considered dream enactments. In addition, Oudiette et al. Consequently, the authors concluded that sleepwalking may represent an acting out of corresponding dreamlike mentation. Recent research suggests that any kind of motor behavior during sleep can be considered an oneiric behavior.

One of the challenges for future research is to test the strength of the link between these oneiric behaviors and dream reports in a controlled and systematic way. Despite the numerous neuroimaging studies of sleep in humans, the neurophysiological correlates of dreaming remain unclear. This phenomenon is difficult to understand given what we currently know about the sleeping brain and about dreaming.

One explanation may rely on the possibility that brain activity during sleep is not as stable as we think. Brain activity during REM sleep in humans is considered to be well understood Hobson and Pace-Schott, ; Schwartz and Maquet, ; Nir and Tononi, , but several results question this notion. First, contrary to the common belief that dorsolateral prefrontal cortex activity decreases during REM sleep, several studies have reported increased activity in the dorsolateral prefrontal cortex during REM sleep Hong et al.

Second, brain activity during REM sleep is heterogeneous. Finally, few congruencies have been noted in the results of studies investigating brain activity during REM sleep Hong et al. Furthermore, few brain regions are consistently reported across the majority of the studies. This inconsistency suggests great intra- and intersubject variability in brain activity during REM sleep in humans.

A challenge for future research will be to find out whether the variability in brain activity during REM sleep can be explained by the variability in dream content.

Because dream reports can be collected after awakenings from any sleep stage, one may hypothesize that the brain activity that subserves dreaming if such brain activity is reproducible across dreams is quite constant throughout the night and can be observed during all sleep stages.

Some results have supported this hypothesis and encouraged further attention in this direction. Interestingly, some authors have suggested that decreased power in the alpha band during wakefulness reflects search and retrieval processes in long-term memory for a review, see Klimesch, This result tells us that internal processes control and shape dream content and thus help us to constrain and shape hypotheses about the function and biological basis of dreaming.

At the end of the nineteenth century, Saint-Denys showed that a sensory stimulus e. The author demonstrated that the external world can influence dream content in a direct or indirect way. Finally, it appears that both external and internal parameters can shape or govern dream content. Nonetheless, few of these parameters are known, and some regularities in the phenomenology of dreams suggest that more influencing parameters remain to be discovered.

For example, some individuals experience recurring themes, characters, or places in their dreams. However, the rule s governing which lived events are incorporated into dreams remain unknown. Do the representations constituting the dream emerge randomly from the brain, or do they surface according to certain parameters?

Psychoanalysis, which was developed by the neurologist Sigmund Freud in the beginning of the twentieth century, proposes answers to the questions raised above. Indeed, his theory of the human mind comprises hypotheses about the rules of selection and organization of the representations that constitute dreams. At the beginning of the twentieth century, Freud presented the concept of the unconscious. He proposed that a part of our mind is made up of thoughts, desires, emotions, and knowledge that we are not aware of, but that nevertheless profoundly influence and guide our behaviors.

In his books e. Its expression, however, is coded within dreams the work of dream , and unconscious thoughts are distorted before they emerge in the conscious mind of the sleeping subject manifest content of the dream.

As a consequence, the dreamer is not disturbed by repressed and unacceptable thoughts latent content of the dream and can continue sleeping this is the reason why Freud considered dreams the guardians of sleep.

As a consequence, Freud developed techniques to decode dreams and provide a way for an analyst to look inside the words and unconscious images of the patient, and to free them through patient insight. One of these techniques is called free association, and is regarded as an essential part of the psychoanalytic therapy process. Free association is the principle that the patient is to say anything and everything that comes to mind.

Over time, the therapist or analyst will draw associations between the many trains of uncensored speech the patient shares during each session. Hence, Freud considered that dreams, as well as slips, have a meaning and can be interpreted, so that one is justified in inferring from them the presence of restrained or repressed intentions Freud, , A psychic process is nothing more than the purpose which it serves and the position which it holds in a psychic sequence.

It gives access to an unknown dimension of ourselves that is fundamental in understanding who we are. It provides access to personal meaning. However, this situation may change as the relationship between psychoanalysis and neuroscience evolves. The starting point was the creation of the International Society for Neuropsychoanalysis in It was founded by neuropsychologist and psychoanalyst Mark Solms with the intention to promote interactions and collaborations between psychoanalysis and neuroscience.

Finally, he presented his model of dreaming, the activation-synthesis hypothesis Hobson and McCarley, ; Hobson et al. In doing so, these chaotically generated signals arising from the brain stem acted as a physiological Rorschach test, initiating a process of image and narrative synthesis involving associative and language regions of the brain and resulting in the construction of the dream scenarios.

He argued that it is generally accepted that brain stem activation is necessary, but not sufficient, to explain the particular characteristics of dream consciousness. What does explain the particular characteristics of dream consciousness, according to Solms, are the following features of brain activity during REM sleep Braun et al. He further argued that his lesion studies Solms, are congruent with neuroimaging results because they showed that a total cessation of dreaming results from lesions in the medial part of the frontal lobe and in the temporoparietal junction whereas no cessation of dreaming was observed for core brainstem lesions or for dorsolateral prefrontal lesions.

Finally he emphasized that the activation of motivational mechanisms such as drives and basic emotions and of posterior perceptual system associated with deactivation of the executive control i. Note that experimental results demonstrating the existence of unconscious representations that guide behavior e.

This debate was a success for Mark Solms and neuropsychoanalysis. He proposes that dreaming and REM sleep are controlled by different brain mechanisms. According to Solms, REM sleep is controlled by cholinergic brain stem mechanisms, whereas dreaming is mediated by forebrain mechanisms that are probably dopaminergic.

This implies that dreaming can be activated by a variety of NREM triggers. Several experimental results support this hypothesis. First, behavioral studies have demonstrated that the link between REM sleep and dream reports is lax.

In addition, in healthy subjects with a normal dream recall frequency around 1 dream recall per week, Schredl, , dream recall after an awakening during REM sleep is not systematic: Second, as Solms argued, the amount of dream recall can be modulated by dopamine agonists Scharf et al.

Dream recall can be suppressed by focal brain lesions at the temporo-parieto-occipital junction and ventromedial prefrontal cortex; Solms, , These lesions do not have any appreciable effects on REM frequency, duration, or density Kerr et al. Finally, some clinical studies suggest that a dream can be triggered by nocturnal seizures in NREM sleep, i.

Some cases of recurring nightmares caused by epileptiform activity in the temporal lobe have indeed been reported Solms, Considering the issues that remain unresolved e. Thus, both psychology and neuroscience have provided results and hypotheses that validate the possibility that dreaming has something to do with personal and meaningful issues. On the other hand, Freud argued that the unconscious, which guides behaviors and desires, express itself during dreams. Note that some experimental studies in psychology have considered the psychoanalytic perspective.

For example, Greenberg et al. They showed that problems occurred very frequently in the manifest dream content and that these problems were nearly systematically related to the problems noted during pre-sleep wakefulness. In addition, they observed that effective dreams i.

This study thus confirmed that personal concerns influence dream content. In addition it provided new results suggesting that dreaming may have some psychological problem-solving function this result recalls the neuroscientific findings that sleep has a cognitive problem-solving function associated with brain reorganization; e.

To proceed further, approaches integrating psychoanalysis and neuroscience must now be developed. This limitation hampers the understanding of psychological and neurophysiological functioning in humans.

These issues must be addressed, and the expertise of psychoanalysts in singularity and personal meaning is needed to do so in neuroscience and to further the understanding of dreaming and of the psyche.

The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. National Center for Biotechnology Information , U. Journal List Front Psychol v. Published online Nov This article was submitted to Frontiers in Psychoanalysis and Neuropsychoanalysis, a specialty of Frontiers in Psychology. Received May 16; Accepted Oct This is an open-access article subject to a non-exclusive license between the authors and Frontiers Media SA, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and other Frontiers conditions are complied with.

This article has been cited by other articles in PMC. Abstract Dreaming is still a mystery of human cognition, although it has been studied experimentally for more than a century. Experimental Research on Dreaming Dreaming and experimental psychology Dream content Dreaming was first investigated on an experimental level in the nineteenth century. Dream report frequency Dream report frequency DRF can vary within subjects and varies substantially among subjects.

Sleep parameters First, DRF varies according to the sleep stage preceding awakening e. Physiological and environmental parameters Dream report frequency deceases with age e. Psychological parameters First, increased professional stress or interpersonal stress resulted in an increase in DRF for a review, see Schredl, Dreaming and neuroscience The neuroscientific approach to dreaming arose at the end of the s with the discovery of REM during human sleep by the American physiologist Nathaniel Kleitman and his team Aserinsky and Kleitman, ; Dement and Kleitman, a.

Hypotheses about dream function s No function At the end of the twentieth century, the neurologist Alan Hobson, who was profoundly anti-psychoanalysis, proposed a theory that deprived dreaming of any function. The threat simulation theory The Finnish psychologist Antti Revonsuo recently proposed a hypothesis called threat simulation theory, which explains the fearful characteristics of dream content Revonsuo, ; Valli and Revonsuo, Emotional regulation Cartwright et al.

Memory consolidation Finally, a current mainstream hypothesis in cognitive neuroscience credits sleep and dreaming with a role in memory consolidation for a recent review, see Diekelmann and Born, Unresolved Issues The link between oneiric behaviors and dream reports A piece of evidence in favor of a strong link between REM sleep and dreaming is the oneiric behavior the appearance of complex motor behaviors when motor inhibition is suppressed during REM sleep discovered by Sastre and Jouvet in cats and reproduced by Sanford et al.

Neurophysiological correlates of dreaming Despite the numerous neuroimaging studies of sleep in humans, the neurophysiological correlates of dreaming remain unclear. Dreaming, Psychoanalysis, and Neuropsychoanalysis Psychoanalysis, which was developed by the neurologist Sigmund Freud in the beginning of the twentieth century, proposes answers to the questions raised above. Conflict of Interest Statement The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Fear, faces, and the human amygdala. The four postulates of Freudian unconscious neurocognitive convergences. Regularly occurring periods of eye motility, and concomitant phenomena, during sleep.

Science , — The function of dream and dreamer variables in the question of dream recall. Tonus of extrinsic laryngeal muscles during sleep and dreaming.

Science , A replication of the day dream-lag effect with comparison of dreams to future events as control for baseline matching. Trait and neurobiological correlates of individual differences in dream recall and dream content.

Dissociated pattern of activity in visual cortices and their projections during human rapid eye movement sleep. The students were woken at various times and asked to fill out a diary detailing whether or not they dreamt, how often they dreamt and whether they could remember the content of their dreams. While previous studies have already indicated that people are more likely to remember their dreams when woken directly after REM sleep, the current study explains why.

Those participants who exhibited more low frequency theta waves in the frontal lobes were also more likely to remember their dreams. This finding is interesting because the increased frontal theta activity the researchers observed looks just like the successful encoding and retrieval of autobiographical memories seen while we are awake.

That is, it is the same electrical oscillations in the frontal cortex that make the recollection of episodic memories e. Thus, these findings suggest that the neurophysiological mechanisms that we employ while dreaming and recalling dreams are the same as when we construct and retrieve memories while we are awake. In another recent study conducted by the same research team, the authors used the latest MRI techniques to investigate the relation between dreaming and the role of deep-brain structures.

In their study, the researchers found that vivid, bizarre and emotionally intense dreams the dreams that people usually remember are linked to parts of the amygdala and hippocampus. While the amygdala plays a primary role in the processing and memory of emotional reactions, the hippocampus has been implicated in important memory functions, such as the consolidation of information from short-term to long-term memory.

Scientists have also recently identified where dreaming is likely to occur in the brain. However, it was not until a few years ago that a patient reported to have lost her ability to dream while having virtually no other permanent neurological symptoms. The patient suffered a lesion in a part of the brain known as the right inferior lingual gyrus located in the visual cortex.

Thus, we know that dreams are generated in, or transmitted through this particular area of the brain, which is associated with visual processing, emotion and visual memories. Taken together, these recent findings tell an important story about the underlying mechanism and possible purpose of dreaming. Dreams seem to help us process emotions by encoding and constructing memories of them.

What we see and experience in our dreams might not necessarily be real, but the emotions attached to these experiences certainly are. Our dream stories essentially try to strip the emotion out of a certain experience by creating a memory of it. This way, the emotion itself is no longer active. In fact, severe REM sleep-deprivation is increasingly correlated to the development of mental disorders.

In short, dreams help regulate traffic on that fragile bridge which connects our experiences with our emotions and memories.

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Need to sleep on that big decision? Your dreams might influence your final choice, suggests new research. Scientists disagree as to what extent dreams reflect subconscious desires, but new research reported in the Journal of Personality and Social Psychology (Vol. 96, No. 2) concludes that dreams do. From ancient times when dreams were considered to hold prophetic powers to the neurological phenomena studied today, dreams remain one of psychology’s most enduring mysteries. Although scientists continue to research the answers to these questions, they build their work on some commonly accepted dream theories.

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Dreams articles and more. Close × Learn More Psychology Download psychology articles, Body Language & Dream Interpretation guides and more Download articles, guides and more! Dreams are the language of a person's subconscious mind. Before a person starts to dream, there are certain cylces or stages that a person goes through in their sleep. Sleeping is important in our lives. Essay/Term paper: Dreaming and sleeping Essay, term paper, research paper: Psychology. See all college papers and term papers on Psychology.