Introduction

Mankind has always wondered what dreams mean and what purpose they serve. Some have invoked divine origin, mythological origin and psychological reasons for dreaming. Others have hypothesized that dreams can serve as guidance on how to live our wake lives. Some have also explored dream physiology, hypothesized a neurocognitive theory of dreaming, a mind clearing function for dreaming and developed a brain basis for dreaming1,2.

Few, however, have studied how dreams form. Several authors that have include Hobson and McCarley in their Activation Synthesis theory of dreaming, though Hobson and McCarley mostly address the activation mechanism of dreaming and not how dreams form, the synthesis component of their activation Synthesis theory2. Kahn and Hobson address only the self-organizing part of dream formation in their self-organization theory of dreaming3,4. Domhoff addresses the neurocognitive aspects of dreaming in his neurocognitive theory of dreaming5. Nir and Tononi address the question of dreaming as imagination compared to dreaming as perception, but not the mechanism of dream formation30.

This paper hypothesizes that dream formation occurs when the raw material of dreams is combined through a process of emergence without the brain-mind directing the process unless becoming lucid. The raw material of dreams is individual thoughts, feelings and images that arise in the mind when asleep which may come from day residue, distant memories or even from randomly generated thoughts. The experimental evidence for absence of executive direction comes from studies6,7 which show that in dreaming the role of the brain’s executive regions is minimized unless becoming aware one is dreaming (becoming lucid). When lucid the executive areas reactivate so the lucid dream incorporates both undirected and directed thoughts8. In both the lucid and non-lucid state a dream is the emergent product of interacting thoughts, feelings and images.

This paper also hypothesizes that the neural basis for emergence of a dream from individual activity in the mind is the collective neuronal firing that emerges from activity of individual neurons as neurons that initially only fired individually begin to fire collectively. Experimental evidence for the emergence of collective neuronal firing comes from studies of neuronal firing in cultures9.

Emergence

Emergence happens when new properties and behaviors arise whose characteristics cannot be predicted from knowledge of the constituents10,11. For example, when individuals or societies interact with one another, the collective behavior of the whole is different from that of its parts. We call this resulting behavior emergent. Emergent products transcend and are different from the elements that made them up. The emergent product is not directly specified in the interaction laws of the individuals.

Emergence is ubiquitous in physical systems and in nature12,13,14,15. It is a common process by which something whole emerges from its parts. Examples include the emergence of a laser from multiple frequencies of light, an intricate termite mound arising from the collective work of termites16, a waterproof raft arising from simple body attaching behavior of fire ants, 17, a multicellular organism arising from the food seeking behaviors of single celled organisms18, flocking formations arising from simple rules followed by individual birds such as, keep a distance away to match the neighbors’ velocity and stay close to a nearest neighbor19,20, and like-minded humans self-organize into city neighborhoods 21,22. Emergence can also create a top-down feedback from the final emergent product to the individuals that went into making the final product – the termite mound influences the subsequent behavior of termites, the flock influences the motion of individual birds and city neighborhoods change the behavior of the people living there.

The above are mostly examples of emergent systems that lead to overall predictable structure or behavior, such as the termite nest and bird flocking 10. In these cases, the emergent system comes from relatively simple behavior (the laying down of scent and the dropping and picking up behavior of termites, flying near the group but not too close to any individual bird), and result in a predictable outcome (a termite mound, flocking formation).

Other emergent systems are ones in which the final form cannot be predicted in advance. Dreams, we hypothesize are an example of this kind of emergent system. Since dreams emerge from the collective interaction of thoughts, feelings, and images, and given the large combinatorial possibilities and diversity of thoughts, feelings and images, dream content is largely unpredictable despite the occurrence of recurring themes such as being chased, being unprepared or missing travel connections, or because of persisting wake-life anxieties. Although there are recurring themes in dreams, the exact dream, however, is almost never repeated unless the dreamer suffers from Post Traumatic Stress Disorder, where a traumatic event is relived nightly.

As for a function for dreams, researchers have postulated that the dream helps to make new connections or help with wake-life situations and issues by acting as a simulation of them in a safe environment23, though other dream researchers believe dreams have meaning but serve no function in ones wake life5. While we do not directly address the function or lack of function of dream content in this paper, dreaming is functional because it brings disparate elements into a dream structure. The emergence of a dream from loosely connected memory fragments and images forms the core functionality of the dream.

Dream report

The following dream report is taken from a study in which subjects were asked to write a dream report, record all the characters that appeared and to compare thinking within the dream to thinking when awake. This dream report illustrates the formation of a dream as characters, objects and feelings appear. The dream continues to evolve as the on-going dream changes and new characters and objects appear.

Excerpt from dream of CR “Me and Mom”

I am suddenly in the car with my mother… As we drive we end up at the Golden Gate Bridge which was here in Massachusetts. There is a camcorder somewhere in the car. Next we go to South Boston where a new Pizza Hut is having an opening day. Ryan is helping to run the opening. He does not resemble Ryan. I stare at him noticing his features were not his, but it is him. A woman I used to work with at a grocery store comes and is being interviewed. She begins to complain that Ryan gave her half a cookie when she ordered, not a whole one,…As she talks she is playing with some change on the counter. Next, my mother is now running a cash register … My mother jumps up, but does not resemble her anymore. Heavier and shorter. A person shows up in front of me. I wonder if this person is my sister but I am not sure. Ryan turns into a guy I know from school who makes me nervous. Next I am looking at the camcorder from the car and my roommate shows up beside me. I show her the shots of the Golden Gate Bridge my brother got from the front seat.

This example doesn’t prove, of course, that emergence is the only way a dream can form. It is an example of disparate elements evolving into a dream (in car with mother, woman being interviewed, feeling nervous, Golden Gate Bridge, camcorder, cookie, cash register, Ryan, her sister, her roommate, etc.). The specific memory fragments in the mind of the dreamer may have a psychological basis, may reflect current concerns, or may occur for no obvious reason, but they are still fragments until a dream emerges. Even if the individual memory fragments had a psychological basis, the dream that emerges goes beyond these to produce something entirely new that are not predictable from these elements from which the dream was created. If dreams were not emergent, thoughts, feelings and images would remain unconnected fragments3. The dream transcends these in the sense that the dream has a structural form not yet present in the thoughts and images that went into making up the dream. The structural form is the narrative of the dream that contains what Hobson, 1 has called the formal properties of dreams, namely, uncertainty, discontinuity, incongruity and bizarreness. These properties all appear in the above dream report.

Demonstration of collective neuron firing

On a neural level, the collective emergence of a dream from the interaction of thoughts and feelings is related to the emergence of collective neuron firing from the interaction of individual neurons. 9 demonstrated this emergence of collective neuron firing in a recent study in which researchers grew neurons in culture. Using a high-contrast bright-field image they found bursts of coordinated neuronal firing in the early process of cell division. Even though the neuron activity began in a non-coordinated way, it evolved into a state of coherent activity in a few days when many neurons became simultaneously activated. The firing of single neurons thus produced a connection network whereby multitudes of neurons evolved into a state of coherent activity. The authors state that the neuron activity was characterized by “robust, nearly periodic, episodes of collective neuronal firing” and that even though the firing that preceded the bursts seemed to generate randomly, the bursts originated from only a few regions that arose as an emergent property from an implosive concentration of neuronal interactions9.

In addition to the emergence of collective neuronal firing from neurons in culture is the emergence of collective neuronal oscillations in living brains. These collective oscillations included alpha, beta and theta waves, ponto-genicolo-occiptal (PGO) waves and 40 Hz gamma oscillations and the in the dreaming brain24. The 40 Hz gamma oscillations has been associated with cognitive processing when awake and when dreaming24,25, and when gamma waves were induced via transcranial alternating stimulation that reactivated executive portions of the brain, dreaming became lucid8.

Daydreaming, and changes in the sleeping brain

We may ask if daydreaming with only minimal overt direction from the daydreamer may too arise out of an emergent process. The answer is yes, but the differences between daydreaming and night dreaming are important. The most important of which is the radical change in brain chemistry that occurs when dreaming at night, especially in REM sleep. Even though dreams emerge in all stages of sleep they are generally more complex during the rapid eye movement (REM) stage of sleep when brain network connectivity and the brain’s ability to integrate information are high26 and the brain’s chemistry changes. The chemical changes that occur in REM sleep include an enhanced cholinergic and diminished aminergic concentration of norepinephrine from the locus coeruleus, of serotonin from the dorsal raphe nucleus, and histamine from the tuberomammillary nucleus1. Since aminergic modulation is required for attentive behavior, the lack of aminergic modulation together with an enhanced cholinergic modulation in dreaming leads to hallucinatory effects, bizarreness and altered logic in dreams. These often go unrecognized because of the inability to perform reality checks while sleeping.

Also, when dreaming in REM sleep there is dramatic changes in the brain’s regional activity. These regional changes in brain activity include diminished activation of the executive portion of the brain, the dorsal lateral prefrontal cortex and also the precuneus in the parietal lobe6,7. This lessened activity from the executive prefrontal cortex and the precuneus leads to disengagement of executive control over the dream story, makes one unaware of lying in bed asleep and makes one unaware that one is dreaming unless the prefrontal and parietal areas reactivate leading to lucid dreaming27,8. The limbic emotional system, on the other hand, is generally more active in dreaming sleep compared to when awake contributing to the heightened emotional quality of dreams6,7.

Taken together, a dream unlike a daydream emerges from activity that takes place in a brain that has changed from a balanced aminergic-cholinergic milieu when awake to a highly cholinergic one, and that has changed from balanced regional brain activation when awake to one where the executive and self-awareness portions are diminished and the emotional limbic system is enhanced. Further, while the mind is free to wander when daydreaming, unlike the large repertoire of topics that occur in night dreaming, studies have shown that in a daydream we often find ourselves making plans for a future event thinking, about what to wear or what to bring, or we might find ourselves dwelling on what we said in a past conversation.

Conclusion

This paper has hypothesized that dreams form through the process of emergence.

The dream as an emergent product leads to dream content that is largely unpredictable even when knowing individual content. This is a hallmark of emergence, something new is created from the collective interaction of initially individually interacting elements.

Dreams have meaning and dreams serve a function but not necessarily because of the specific content of the dream. Rather it is because the emergent dream gives rise to a story. Before memories coalesced into a dream, meaning resided only in the individual images. When a dream forms, however, meaning resides in the story and in the experience felt from the story. The creation of the dream serves the function of tying individual memories into a whole. Functionality comes only after the disparate memories form into a dream. This kind of functionality is independent of the specific content of the dream.

The dreamer once awake can use the story/experience that emerges to uncover meaning. We argue that the very process of dreaming is functional because a dream has emerged from the collective interaction of individual memories leading to new, modified and unusual situations that may provide new ways to think about and experience life.

Examples of emergence in nature illustrate how emergence can be functional. A termite nest is formed from the collective interaction of individual termites. The emergence of a termite next insures the survival of the termite colony, without the nest, the individual termites would die.

The emergence of a bridge constructed of and by ants insures the survival of the species. Before the emergence of the bridge made up by the collective interaction of individual ants, the ants would have starved to death unable to reach a food source on the other side of a body of water.

The emergence of a multi cellular organism, the slime mold insures the survival of a colony of individual amoebae. The individual amoeba has no way to move to a food source. The collective interaction of the amoeba results in the emergence of an organism that cam propel itself to find a food source.

The emergence of a neighborhood, town and city from the collective interaction of like-minded people help create infrastructure suitable for larger numbers of people.

Limitations

A limitation of emergence theory applied to dream formation is that it does not directly address how subjective experience arises from brain activity, that is, the theory of emergence does not address how the brain and its neurons lead to the subjective experience of dreaming (or to any subjective experience).

One can speculate that the process of emergence not only leads to a dream but to the very subjective experience of dreaming itself from the interaction of neural activity and brain chemistry. This has yet to be demonstrated. Here we content ourselves with hypothesizing that a dream is a product of an emergent process arising form the interaction of thoughts, feelings and images in the mind of the dreamer and that it’s neural basis may be the emergence of collective neuronal firing. Dreaming, no less than waking is a fundamental state of consciousness23,28,29 and dreams are the emergent products of this state of consciousness.