Anxiety levels in dreams: relation to localized cerebral glucose metabolic rate

Functional roles of REM sleep

Rapid eye movement (REM) sleep is an enigmatic and intriguing sleep state. REM sleep differs from non-REM sleep by its characteristic brain activity and from wakefulness by a reduced anti-gravity muscle tone. In addition to these key traits, diverse physiological phenomena appear across the whole body during REM sleep. However, it remains unclear whether these phenomena are the causes or the consequences of REM sleep. Experimental approaches using humans and animal models have gradually revealed the functional roles of REM sleep. Extensive efforts have been made to interpret the characteristic brain activity in the context of memory functions. Numerous physical and psychological functions of REM sleep have also been proposed. Moreover, REM sleep has been implicated in aspects of brain development. Here, we review the variety of functional roles of REM sleep, mainly as revealed by animal models. In addition, we discuss controversies regarding the functional roles of REM sleep.

Neuroanatomical characterization of Fos induction in rat behavioral models of anxiety

Immunohistochemical staining for Fos-like immunoreactivity (Fos-LI) was used to map functional activation in discrete brain regions of rats processed in three empirical models of anxiety: foot shock avoidance responding in a shuttle box, the elevated plus maze, and an air puff-induced ultrasonic vocalization test. The avoidance test and elevated plus maze induced prominent Fos-LI in select brain regions, including the medial prefrontal, cingulate, and ventrolateral orbital cortices, taenia tecta, nucleus accumbens, paraventricular nucleus of the hypothalamus, medial nucleus of the amygdala and lateral septum. Air puff stimuli that produced ultrasonic vocalizations induced Fos-LI to a more limited extent compared to the plus maze and avoidance test, with only the medial prefrontal cortex, medial nucleus of the amygdala, and lateral septum being significantly affected by air-puff. Even though the sensory stimuli and environmental conditions associated with the three anxiety models were markedly different, specific common forebrain regions were affected, i.e. the medial prefrontal cortex, medial amygdala, and lateral septum. It is hypothesized that these regions are components of a circuit in the rat brain related to anxiety or distress. To determine the potential relationship between generalized arousal and the observed induction of Fos-LI in the anxiety models, rats were tested in a non-aversive situation involving marked behavioral activation. Accordingly, after vigorous bar pressing behavior for reinforcement with sweetened condensed milk, induction of Fos-LI was minimal and comparable to that in unhandled control rats. These latter data indicate that the distinctive neuroanatomical patterns of Fos-LI observed in the paradigms related to anxiety were not simply due to generalized behavioral activation. In summary, select common brain regions were identified that express Fos-LI in empirical models of anxiety. These data provide a functional framework to explore neuroanatomical sites of action of psychotherapeutic drugs that influence behavioral responses in these tasks.

The cerebral neurobiology of hope and hopelessness

Hope and hopelessness are useful constructs that have been employed by clinicians in theory making regarding the pathogenesis and course of disease and in the application of various psychological and medical treatments to illness. French (1952) and Frank (1968) viewed hope as a necessary motivating force in influencing an individual to try to overcome inner psychological conflicts and seek to resolve a psychoneurosis. Melges and Bowlby (1969) classified the types of hopelessness in psychopathological processes. Perley et al. (1971), using an objective method for content analysis of small samples of speech (Gottschalk 1974), found that elevated hope scores predicted continuation of psychiatric treatment rather than dropping out. Gottschalk et al. (1967, 1969) found that hope scores derived from verbal samples predicted the duration of survival of patients with terminal cancer receiving irradiation treatment (1969) and predicted relatively favorable outcome in psychotherapy (1967).

The relationship between social alienation and disorganized thinking in normal subjects and localized cerebral glucose metabolic rates assessed by positron emission tomography

This study investigated the relationships between the relatively mild manifestations in verbal behavior of social alienation and disorganized thinking in normal subjects and cerebral glucose metabolic rates measured by positron emission tomography (PET). Three groups of 10 young normal male subjects were injected with D-[18F]deoxyglucose (FDG) during either wakefulness, rapid eye movement (REM), or non-REM (NONREM) sleep, and 32 to 45 minutes later they were asked to report their thoughts, emotions, or dreams and free-associations to these mental events. Nonparametric correlations were obtained between measures of interpersonal social alienation, intrapsychic conflicts, and thought disorder derived from the typescripts of these reports by content analysis--using the Gottschalk-Gleser Social Alienation-Personal Disorganization Scale--and regional cerebral glucose metabolic rates obtained from PET scans. Total social alienation-personal disorganization scores obtained from the reports of wakeful, silent mentations showed significant positive correlations with glucose metabolic rates in the left temporal lobe. The patterns of significant correlations involving these verbal behavior measures derived from the content analysis of verbal reports of dreams or other mental events occurring during REM and non-REM sleep were in different cerebral locations from those found with these variables during silent, waking mentation. Previous observations suggesting that increased left temporal lobe glucose may typify chronic schizophrenia may instead be indicative of a wide range of thought disorder and/or social alienation manifestations occurring, at times transiently and minimally, in normal people.

The effect of anxiety and hostility in silent mentation on localized cerebral glucose metabolism

Ten normal, wakeful, young (average age, 25.3 +/- 6.6 years) male subjects received positron emission tomographic (PET) scans 45 to 120 minutes after an infusion of D-[18 F]deoxyglucose in order to assess localized cerebral glucose metabolic rates during silent visual and other sensory imagery and cognitive mentation. The typescripts of the verbal reports, limited to 5 minutes, of this type of mentation (including free-associations to all the silent mental events), were blindly content-analyzed to provide objective measures of various kinds of anxiety and hostility. Many significant positive and negative correlations were found in medial cortical, lateral cortical, and subcortical gray matter, and white matter areas between the magnitude of the anxiety and hostility aroused in the silent mental processes and localized cerebral glucose metabolic rates. Clearly, energy consumption in the brain, as judged from localized glucose metabolic rates, is highly influenced by the quality and quantity of emotionally tinged private reveries and mental events occurring spontaneously within human subjects. Brain areas involved with the processing of language, sensation, cognition, memory, and emotional reactions appear to be involved especially in these significant correlations. The implications of such findings in the neurosciences and behavioral sciences are discussed.

Glucose metabolism in psychiatric disorders: how can we facilitate comparisons among studies?

Positron emission tomography (PET) offers a possibility to study brain function and its relationship to psychiatric disorders. Clinical studies have demonstrated that several psychiatric diseases are coupled with changes in brain glucose metabolism. Schizophrenia seems to involve a lower metabolism in wide areas of the brain--both cortical and subcortical structures. Depression probably involves dysfunction of the metabolism in dorsolateral prefrontal cortex. Obsessive compulsive disorder, panic disorder, anorexia nervosa and the experience of anxiety may involve increased metabolic rates. The results from the different studies do not allow quantitative comparisons or detailed analyses because of large differences in experimental and clinical methodology. The term Good Clinical PET Practice (GCPP) is suggested to encourage standardization in clinical investigations. GCPP includes standardization of both experimental factors (lumped constant, arterialization, purity of tracer, regions of interest, relative rates) and clinical factors (state of the subject, wakefulness, anxiety, gender, course of the disease) in PET performance.