خواب مغز / ذهن، آگاهی و روانپریشی

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.

Although almost all the funding pioneers of the modern scientific approach to mental disorders have in some way or another commented on the similarities between dreaming and insanity (Bleuler, 1966, Freud, 1958, Jung, 1936, Kraepelin, 1906 and Minkowski, 1997), only few contemporary researchers have attempted to bind these complex phenomena (Gottesmann, 2006 and Hobson, 2004). Indeed, most of the evidence supporting this observation belongs to a phenomenological perspective, which intrinsically lies on debatable premises due to its reliance on the verbalization of subjective experiences (Mishara, 2007 and Parnas et al., 2008). However, several recent neurobiological findings on both the architecture of dream sleep and severe mental disorders offer intriguing opportunities to bridge mental functioning to underlying brain activity across states. Sigmund Freud was amongst the first to consider dreams at the centre of a complex theorization of mental functioning, and whether or not such theory may now be reconciled with neurobiology remains open to debate (Carhart-Harris, 2007, Hobson, 2004 and Solms, 2004). Indeed, psychiatry’s current loss of interest in dreaming may in part be attributed to a refusal of the central tenet of psychoanalysis, that has often been considered the extreme opposite of a rational scientific approach to the mind. Moreover, dreaming is usually considered a physiological phenomenon of little use in the clinical approach to mental disorders, although several psychologically-oriented investigators have shown statistically significant disorder-specific variations in the dreams of psychiatric patients (Cartwright et al., 2006, Sauteraud and Menny, 1997, Schredl and Engelhardt, 2001 and Zanasi et al., 2010). Dreaming is one of several subjective experiences which may yield significant insight into the functioning of the brain/mind, but two peculiar aspects make it particularly useful in terms of experimental evaluation. First of all, dreaming is generated by the brain in absence of interaction with the external world, possibly the purest form of mental production of a healthy brain (Revonsuo, 2006). Secondly, dreaming recurs with high frequency and little interindividual variability in most human subjects. Although an obvious inter- and intra-individual variability can be found in terms of dream content, the formal organization of this type of mentation appears to be fixed (Scarone et al., 2008 and Stickgold et al., 1994). It has been suggested that themes, emotions and plots of dreams and their intrinsic bizarreness are as much generic to human consciousness as to individual consciousness (Hobson & Kahn, 2007). Two recent theories on dreaming both consider this phenomenon a biologically determined system that has served an evolutionary function for mankind (Hobson, 2009 and Revonsuo, 2000). Although they have been reached from different perspectives, Antti Revonsuo’s Threat Simulation Theory and Allan Hobson’s Protoconsciousness Theory both imply that the phenomenology of dreams is generic and shared amongst individuals. In this paper we will review evidence in support of the view that the dreaming brain/mind resembles psychosis independent of diagnostic categorizations, and may as such be considered a useful experimental model of this complex phenomenon. We believe a convergence of phenomenological and neurobiological observations to be necessary in order to clearly identify these two states of consciousness and their

In spite of several promising advances in neuroscience and psychiatric disorders, clinicians and researchers alike are still at some distance from addressing the core of the problem, the loss of touch with reality. The possibility of using a universal and shared experience to which any observer may have a direct access makes the dreaming model of psychosis particularly useful. Furthermore, dreaming may be studied neurobiologically in healthy subjects that have never taken psychotropic medications or other psychoactive substances. Indeed, research into psychosis is often complicated by the presence of significant drug regimens of which some major effects cannot be excluded. Schizophrenia – a multifaceted disorder – is still the clinical condition within which psychosis may be diagnosed most frequently, and peer-reviewed research into neurobiological and experiential correlates of psychosis is usually derived from schizophrenic patients. For this reason, it is frequent to find an erroneous equation schizophrenia = psychosis in clinical practice and research settings, whereas several aspects of psychosis are known to occur in different disorders and schizophrenia with no relevant psychotic symptoms can occur. It is well known that a great variety of predisposing conditions may precipitate psychosis, namely schizophrenia, manic-depressive illness, unipolar depression, mental retardation, drug intoxication and withdrawal, several metabolic or neurological conditions affecting the anatomy and physiology of the brain. Furthermore, psychosis can occur in response to sensory deprivation such as seclusion and highly stressful events, and underlying neurobiological mechanisms have been hypothesized to involve stress-response cascades resulting in hyperdopaminergic activity in the cortex (Corcoran, Gallitano, Leitman, & Malaspina, 2001). Amongst these conditions, the psychotic experience can be variously expressed from an isolated reference ideation, abnormal self experiences or neurological hallucinoses to full blown, agitated florid substance-induced psychoses. Likewise, dreaming is not a binary experience, either recurring or not, but it may be conceptualized along a continuum from brief sleep-related hallucinatory experiences to intensely vivid or even lucid REM-rebound dreams. Although it is not clear how sleep resembles psychosis, a common underlying mechanism may be found in an evolutionary perspective, with similar processes occurring at the genetic, biochemical and ultimately neurofunctional level in both the emergence of dream sleep in all human subjects and of psychosis in a relatively small percentage of them. In these terms, dreaming has been hypothesized to be a subjective experience lacking secondary consciousness, several aspects of which can be similarly found to diminish in most psychoses (Hobson, 2009).