REVIEW ARTICLE Journal of Biomedical and Pharmaceutical Research 2 (2) 2013, 50-57 * Corresponding author: Prof. Dr. Md. Nazrul Islam, Ph. D. Page50 Page50 Page50 Page50 ISSN: 2279 - 0594 Dream: from Phenomenology to Neurophysiology Dev Kumar Shah, Niraj Khatri Sapkota, Md. Nazrul Islam* Department of Physiology, Chitwan Medical College, Bharatpur, Chitwan, Nepal. ABSTRACT Dream is commonly used to express an unattainable ideal or a very deep and strong desire. Neurophysiological correlation of dreaming are still unclear and many questions remain unresolved, i.e. whether the images in dreams emerge randomly from the brain or they are controlled by currently known/unknown parameters and are determined by any rules; whether dreaming has any meaningful function or it just a byproduct of sleep, etc. Psychoanalytical perspective in cognitive neuroscience helps to achieve a comprehensive understanding of dreaming but it is challenging to interpret rationally. Thus, close interaction between neuroscience and psychoanalysis would probably take the dream research to a new height. KEY WORDS: Dream, brain activity, REM sleep, NREM sleep. INTRODUCTION: Dream represents the conscious awareness of complex brain systems involved in the reprocessing of emotions and memories during sleep (1). Revonsuo refers dreaming to the subjective conscious experiences that we have during sleep (2). Some people rarely remember their dreams and erroneously conclude that they do not dream at all, while others experience vivid dreams with rich visual imagery and emotional content (3). Dreaming was first investigated on an experimental level in the 19 th century. Calkins published the first statistical results about dreaming and argued that some aspects of dream content could be quantified (4). According to psychological studies, visual imagery occurs more frequently in dreams than imagery of other senses (audition, olfaction, touch, and taste). Some elements of real-life events previously experienced by the dreamer often contribute to the scene of the dream and most often, the dream sequence is not within the dreamer’s voluntary control. The dream report is often full of people interacting with each other (e.g. discussions, fights, pursuit, and sexuality) and finally, the dream report often contains strong emotions (5, 6). This article is an attempt to reveal the ambiguities of different aspect of dream like the theories proposed so far to explain its mechanism; its relation with different stages of sleep; activity of different parts of brain during dreaming; content, frequency as well as speculated functions of it. THEORIES OF DREAM: PSYCHOANALYTICAL THEORY: This theory, developed by the neurologist Sigmund Freud (3), proposed that a part of our mind is made up of unconscious thoughts, desires, emotions, and knowledge that influence and guide our behaviors. The dream is a highly meaningful product of unconscious mind under the circumstances of sleep. The meaning of dream is not apparent in its manifest content but in the “latent dream thoughts” some of which are unconscious and have to be uncovered by the process of free association. The latent dream thoughts includes conflicted instinctual (i.e., sexual or aggressive) wishes originating in childhood as well as day residues, thought processes typically from the previous day. The latent dream thoughts are transformed into the manifest dream by primary process mechanisms which include condensation (the combining or fusing of two or more elements into a single one), displacement (a shifting of emphasis from one element to a different one) and symbolization. The primary process mechanisms also code the expression of unconscious mind (the work of dream) and distort before they emerge in the conscious mind of the sleeping subject (manifest content of dream). As a consequence, the dreamer is not disturbed by repressed and unacceptable thoughts (latent content of the dream) and can continue sleeping. Hence, Freud debated that dreams have a meaning that can be interpreted and are considered as guardians of sleep. ACTIVATION-SYNTHESIS HYPOTHESIS: The activation-synthesis model of dream construction proposed by Hobson and McCarley (7) states that the phasic signals arising in the pontine brainstem during REM sleep and impinging upon the cortex and limbic forebrain led directly to the visual and motor hallucinations, emotion, and distinctively bizarre cognition that characterize dream mentation. In the activation portion of model, the authors view the brainstem as