Project: "Brain Activity During Dreaming Consciousness: Towards an Evolutionary Perspective"

The project consists of four parts:
1. The first part is to state a basic hypothesis relating dreaming consciousness (formal properties that make a dream a dream) to brain activity during dreaming including selective regional brain activation, selective neuromodulation and selective synchronization between regions in the brain.
2. The second is to provide evidence for the hypothesis from brain imaging and lesion studies.
3. The third part is to provide phenomenological evidence from dream reports.
4. The fourth part is an attempt to understand dreaming consciousness from an evolutionary perspective.

Can forgetfulness of waking events during dreaming inform on the function of sleep?

Introduction. When we are dreaming our memory for facts at best seems inconsistent, and our memory for actual episodes that occurred during the day is pretty miserable. And yet according to the latest research it seems that sleep is important, and maybe even necessary, for the laying down of memories for facts and events that occurred during the day (Stickgold, 1998). This is a conundrum (forgetfulness on the one hand and memory consolidation on the other) that may be related to why we sleep. Since sleep potentially makes the animal very vulnerable, one would expect that there must be some very good reason why sleep evolved and persisted. At one time it was thought that sleep served as a rest for the brain, but this can't be entirely true since for a good portion of the night the brain is not resting but is in a highly activated state called paradoxical or REM sleep. Most recently, there is increasing evidence that sleep, both paradoxical and non-dreaming sleep, is correlated with improved memory for new material learned during the day.

Results of the Fall 1998 project

In the Fall of 1998 I analyzed a character identification database of dream reports (Kahn, 1998). I found that characters known to the dreamer are often not recognized by the dreamer in ways commonly used when awake, for example, by a person's appearance, or behavior, or face. Instead, the dreamer often states "I just knew who it was." This finding was correlated with PET brain imaging studies where it was found that some areas of the brain are more active and others less active in dreaming compared to waking. We hypothesized that this led to a dissociation between brain areas that affect consciousness. Specifically, in dreaming one is not always able to "consciously" identify a face and the name associated with this face because the specialized areas for face recognition (fusiform gyrus) and naming (parts of the frontal and parietal cortex) are not firing in synchrony. This happens because there is only minimal activation of the prefrontal area, even though there is full activation of the fusiform, as found in the PET studies. Some sort of recognition, however, is taking place, perhaps by an emotional feeling, leading the dreamer to say he 'just knows' who that person is.

The project to be undertaken at the KLI in the Fall of 1999 consists of two parts. The first part is an empirical study which is a follow-up to the study performed at the KLI in the Fall of 1998. The proposed follow-up study looks at what the dreamer remembers well and what he forgets or gets wrong about waking reality in his/her dream. This will give us information on the kinds of memory that remains intact and the kinds that do not. These dream reports will be studied in conjunction with existing brain imaging studies to identify specific changes in brain activity with memory impairment in dreaming.

The protocol that will be used to collect data in the Spring of 1999 is shown below. It is the data from this study that will be analyzed at the KLI in the Fall of 1999.

Protocol for empirical study

Rationale. When we dream of people do they appear to us as they would if we were to visualize them during waking consciousness? This study is designed to elicit preliminary evidence on this question.

1. Identity of Characters – State the identity of the character as you determined it in your dream (e.g., my father, my wife, my boyfriend, policemen, group at a party, old man...in the appropriate column

2. Kinds of Identity will be recorded in the next column:

Kind of Identity N = a named (i.e., non-novel character), includes any specific identification such as "my current boyfriend," "my Mom," "Bill S." These are specific individuals who may not be identical in all ways to their waking counterpart but whom you identify within your dream with a specific real known personage.

Kind of Identity G = a generic character(s), which denotes a non-specific identification such as "a friend," "a policeman," "a man with a gun," "a group of people at a party," "a wealthy man," "my lover" but who is not an individual you actually know in your waking life. A character is identified generically if any characterization beyond gender and age is made, e.g., " a wealthy man" is generically identified.

Kind of Identity U = unknown character. A novel character definitely present in the dream but identified only by age or gender without a particular role or interactive relationship with you the dreamer such as an elderly man, or a girl, a woman, a man.

3. Differences between dreamed and waking characters – For all identified characters that you know (N) that you believe represent someone in your waking life, you are to ask yourself "is there something "different" with this character compared to the way you know him/her in real life?" Is there something in this dream character that is at odds with the way you know him/her in real life? This difference could be the dream character's appearance, behavior, face, age, relationship to you, or his/her gender. You will be given a choice of ways the dream character is different from the way you know him/her in real life. You are to mark in the appropriate column which of the given choices most closely matches this difference.

Basic Identity: Mark ID if the dream character is exactly like the waking character in every way. Mark N if the character had a different name from the person they represent in real life. For example, you dream about your wife and know it's your wife but she is called by another name in the dream. Appearance/Behavior: The character had the right name in the dream (e.g., John, or my mother, or Aunt Sadie) but the face or appearance or behavior is different than the person has in real life. Mark F if the face was different. Mark A if his/her appearance was different. Mark B if his/her behavior was different. Mark K if you couldn't pin point the difference but you 'just know' he/she is different. Mark? If you can't remember why he/she was different.

Basic Facts

Mark age if the age of the character you dreamt about, say your son, is very different in real life. So, if you dream about your son Mark who today is 15, but in the dream appears the way he was when a toddler, you would mark Age (even if you too are a different age in the dream than in real life.) Mark D if the character in the dream is alive but in reality the character is dead. For example, in the dream you are having a conversation with your grandmother who in real life has been dead for several years. Mark S if the named or generic character in the dream is of a different gender than in real life.. For example, if the character dreamt about is a man you know named Jim, but in the dream he appears as a woman. Relationship Mark R if the relationship you have with the character in your dream is not the same as it is in real life. For example if in the dream you are married to the character, you are his/her boy/girl friend, his her lover, etc., but you are not in real life at the moment (even if at one time you were).

Feelings

Mark EMS if the feelings/emotions evoked in you by the dream character differ from those evoked in you by the real person in waking.

4. If any of the choices in the previous column doesn't match the difference between the character dreamt about and the one he represents in real life, mark an X in this column and explain in the detail log

5. In the next column mark a T for true if an event in your dream actually happened in real life. You should not mark an event T if it merely resembled the event in real life. An example of an event that should be marked T is if you dream that you had lunch with your Mom in a given restaurant and you actually just did that. However, if you did not have lunch with your mother in that restaurant, or you had lunch with your father rather than your mother you would not mark T. Similarly, if you dreamt that you and your boyfriend went camping and you actually just did go camping with him you should mark a T in this column. However, if in real life you went camping with your sister (or anyone else) you would not mark it as T. So, for an event that occurred in the dream to be marked as T it must be very close to an event that actually happened in real life.

Relating empirical study with function of sleep

In conjunction with this empirical study, the second part of the proposed study hopes to speculate on the function of sleep. If sleep is necessary for certain kinds of memory consolidation and learning, as much of the literature indicates, can the results of the empirical study, which informs on specific kinds of memory loss in dreaming and its relationship to specific changes in brain activity, be reconciled with the laying down of wake memories? Is there a relationship between forgetting certain waking events during dreaming and the learning and laying down of certain kinds of memories of the day during sleep? For example, we almost never dream about an actual event that happened during waking hours like having a cup of coffee at Starbucks after work and reading the novel Martin Dressler there. This informs us on the kinds of brain memory processes that are not active during dreaming sleep. We will speculate on if, and how, this might be connected to memory consolidation of waking memories during sleep.

Summary. This study is aimed at increasing our knowledge of the relationship between brain activity as determined from brain imaging studies, and memory as studied phenomenologically from dream reports. Last year we emphasized that the peculiar cognition of dreaming can be accounted for by a changed brain chemistry (from aminergic in waking to cholinergic in dreaming) and a selective activation of limbic brain areas coupled with a deactivation of the logical and executive areas of the brain during dreaming. This year we hope to continue to investigate the relationship between brain processes and cognition by studying the peculiar memory lapses found in dreaming and by relating these to brain activity observed in PET imaging taken during dreaming sleep. We will speculate on the function of sleep, and the broader question, why did sleep evolve?

REFERENCES Kahn, D. (1998). Consciousness as Activation of, and Synchrony between specific brain areas: special case of dreaming. Report for the KLI. Stickgold R. (1998). Sleep: off-line memory reprocessing. Trends in Cognitive Sciences 2: 484-492.

Ph.D. Physics, Yale University. Research Fellow Department of Psychiatry, Harvard Medical School, Harvard University  

Recent Publications:

Hobson, J.A., Pace-Schott, E.F., Stickgold, R. and Kahn, D. (1998). To dream or not to dream? Relevant data from new neuroimaging and electrophysiological studies. Current Opinion in Neurobiology. 239-244.

Kahn, D., Krippner, S., Combs, A. (Submitted). Dreaming and the self-organizing brain.

Kahn, D., Pace-Schott, E.F., Stickgold, R. and Hobson, J.A. (1998). Specification of the activation-synthesis model of dreaming: A review of recent findings on regional brain activity and neurochemistry during REM.  The Association for the study of Dreams Abstracts

Kahn, D., Krippner, S., Combs, A. Dreaming Brain as a self-organizing system. Towards a Scientific Study of Consciousness, Tuscon III Abstracts

Kahn, D., Pace-Schott, E.F., and Hobson, J.A. (1998). Neuropsychology of dreaming consciousness. Towards a Scientific Study of Consciousness, Tuscon III Abstracts

Kahn, D., Pace-Schott, E.F., and Hobson, J.A. (1997). Consciousness in waking and dreaming: the roles of neuronal oscillation and neuromodulation in determining similarities and differences.  Neuroscience 78:13-38.

Kahn, D., Pace-Schott, E.F., and Hobson, J.A. (1997). Amygdala activation, emotion and dreaming: a new look at the activation synthesis model. Association for the study of dreams abstracts.

Kahn, D., Pace-Schott, E.F., and Hobson, J.A. (1996). Binding and consciousness in the wake and dream states. Association for the study of dreams abstracts.

Kahn, D., and Hobson, J.A. (1995). Coherent oscillations in the wake and REM states suggest a self-organizing brain. Association for the study of dreams abstracts

Kahn, D., and Hobson, J.A. (1994). Unpredictability and meaning in self-organized dreaming. Association for the study of dreams abstracts

Kahn, D., and Hobson, J.A. (1993). Self-organization theory of dreaming. Dreaming 3:151-178.

Talks at the KLI

"Brain Activity During Dreaming Consciousness"
KLI Brown Bag Discussions 1998

"Consciousness while asleep: Feelings evoked by Dreamcharacter"
KLI Brown Bag Discussions 1999

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