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PubMed1998

Angiotensin II-nitric oxide interaction on sympathetic outflow in conscious rabbits.

Increasing evidence suggests that endogenous NO inhibits sympathetic outflow in anesthetized animals. However, in a recent study from this laboratory, we were unable to find any evidence of increased renal sympathetic nerve activity (RSNA) in response to blockade of NO synthesis in conscious rabbits. Because angiotensin II (Ang II) increases sympathetic outflow, one factor for this discrepancy may be the difference in the resting level of Ang II, which may be lower in well-trained conscious animals. In the present study, the effects of blockade of NO synthesis with Nomega-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg IV) on resting RSNA with and without a background intravenous infusion of Ang II (10 ng.kg(-1).min(-1)) was investigated in conscious rabbits. Intravenous administration of L-NAME (30 mg/kg) caused an increase in mean arterial blood pressure (MAP, from 80.4+/-2.9 to 92.8+/-2.5; P=.0001) and a decrease in RSNA (from 100+/-0% to 53.4+/-8.6%, P=.0016). When the elevated blood pressure was returned to control by infusion of hydralazine (0.01 to 0.06 mg.kg(-1).min(-1)), RSNA returned to the level before L-NAME administration. During a sustained infusion of Ang II (10 ng.kg(-1).min(-1)), L-NAME increased MAP from 89.2+/-2.9 to 109.0+/-4.3 mm Hg (P=.0101) and decreased RSNA from 100.0+/-0% to 53.7+/-7.5% (P=.0013). Under this circumstance, however, when the MAP was returned to the level that existed before the administration of L-NAME, RSNA increased significantly above the level that existed before the administration of L-NAME (164.5+/-17.7% versus 100+/-0%, P=.0151). The enhancement of the sympathetic response by Ang II was completely blocked by the AT1 receptor antagonist, losartan. In contrast, during a background infusion of phenylephrine, which increased MAP to the same level as produced by Ang II, L-NAME had no effect on RSNA when MAP was returned to the control level. Nomega-Nitro-D-arginine methyl ester had no effect on MAP and RSNA. Intravenous infusion of Ang II alone for 75 minutes had no effect on RSNA when MAP was returned to control levels. These data suggest that an elevated level of Ang II is critical for the inhibitory effect of NO on sympathetic outflow in conscious rabbits and imply that these two substances have a major impact on the regulation of sympathetic outflow.

Angiotensin II↗
PubMed2002

Functional MRI and the study of human consciousness.

Functional brain imaging offers new opportunities for the study of that most pervasive of cognitive conditions, human consciousness. Since consciousness is attendant to so much of human cognitive life, its study requires secondary analysis of multiple experimental datasets. Here, four preprocessed datasets from the National fMRI Data Center are considered: Hazeltine et al., Neural activation during response competition; Ishai et al., The representation of objects in the human occipital and temporal cortex; Mechelli et al., The effects of presentation rate during word and pseudoword reading; and Postle et al., Activity in human frontal cortex associated with spatial working memory and saccadic behavior. The study of consciousness also draws from multiple disciplines. In this article, the philosophical subdiscipline of phenomenology provides initial characterization of phenomenal structures conceptually necessary for an analysis of consciousness. These structures include phenomenal intentionality, phenomenal superposition, and experienced temporality. The empirical predictions arising from these structures require new interpretive methods for their confirmation. These methods begin with single-subject (preprocessed) scan series, and consider the patterns of all voxels as potential multivariate encodings of phenomenal information. Twenty-seven subjects from the four studies were analyzed with multivariate methods, revealing analogues of phenomenal structures, particularly the structures of temporality. In a second interpretive approach, artificial neural networks were used to detect a more explicit prediction from phenomenology, namely, that present experience contains and is inflected by past states of awareness and anticipated events. In all of 21 subjects in this analysis, nets were successfully trained to extract aspects of relative past and future brain states, in comparison with statistically similar controls. This exploratory study thus concludes that the proposed methods for "neurophenomenology" warrant further application, including the exploration of individual differences, multivariate differences between cognitive task conditions, and exploration of specific brain regions possibly contributing to the observations. All of these attractive questions, however, must be reserved for future research.

Cognition↗
PubMed1976

The "intoxication state of consciousness": a model for alcohol and drug abuse.

The author describes a model of intoxicant use based on altered states of consciousness and reviews his own and others' research on marijuana to illustrate the utility of this model, which is derived from both introspective reports and observed data. The relationship of social behavior and cognitive functioning to the "intoxication state of consciousness" is discussed. This state of consciousness may have an adaptive value in engendering and stabilizing social cohesion. Possible treatment implications include cognitive labeling of cues that precipitate episodes of abuse, training for moderated drug use while patients are intoxicated, and providing abusers with altered consciousness through other means, such as meditation.

Alcoholic Intoxication↗
PubMed1978

The psychology of consciousness.

All psychologic phenomena occur in consciousness. However, "consciousness" has two meanings: the faculty and the content of awareness. Traditional psychologies have largely concerned themselves with the content, neglecting the problem of the faculty, thus, limiting our understanding of human psyche. Study of meditation is a viable approach to the exploration of both meanings of consciousness. Meditation aims at a "cleansing" of the mind to reach, thereby, a content-free and conflict-free state--pure consciousness.

Awareness↗
PubMed1989

Consciousness as a dissipative structure: an extension of the Newman model.

Newman's model of health as the expansion of consciousness and Prigogine's theory of dissipative structures provide the framework for the development of a model of consciousness as a dissipative structure. Relationships among Type A behavior, temporal orientation, and death anxiety are examined and explicated within the human field pattern of consciousness as a dissipative structure. Type A behavior, future orientation, and death anxiety are proposed as manifestations of consciousness with the potential to evolve to higher levels in accordance with Prigogine's theory. Preliminary research findings related to the model and suggestions for future research are also presented.

Attitude to Death↗
PubMed2005

Schizophrenic consciousness, spiritual experience, and the borders between things, images and words.

A prototypical feature of schizophrenic consciousness is that it undergoes a solidification of the imaginary space in which mental events take place. The bipartition between images and 'real' things is jeopardized and imagination is transformed into 'physical' forms. Parallel to this solidification of imaginary space in schizophrenic consciousness, more generally the rigid tripartite separation of things, images and words upon which the spatial order of consciousness is founded starts to erode. I explore different spiritual and philosophical traditions which shed light on and make more understandable the schizophrenic consciousness that call into question this separatedness. I argue that these traditions indicate that our current commonsensical approach to the separatedness between things, images and words is historically and culturally determined.

Consciousness↗
PubMed2000

Comparing the relative fit of various factor models of the self-consciousness scale in two independent samples.

Research shows that using highly self-aware participants yields studies of higher reliability, validity, and statistical power; dispositional self-awareness is commonly measured using the Fenigstein Self-Consciousness Scale (Fenigstein, Scheier, & Buss, 1975). This study used confirmatory factor analysis to compare various factor models that may underlie that scale. Two independent student samples (296 from Bernstein, Teng, & Garbin, 1986, and 350 from a large Canadian university) completed the scale. Using 6 fit criteria, results from both samples supported the Burnkrant and Page (1984) 4-factor model, namely, that self-consciousness consists of 3 principle scales: Social Anxiety, Public Self-Consciousness, and Private Self-Consciousness (divided into Internal State Awareness and Self-Reflectiveness). We discuss the psychometric implications of enhancing scale reliability, validity, and self-awareness.

Adolescent↗
PubMed2002

Gamma coherence and conscious perception.

BACKGROUND: High-frequency (e.g., gamma 30 to 50 Hz) coherent neural activity has been postulated to underlie binding of independent neural assemblies and thus integrate processing across distributed neuronal networks to achieve a unified conscious experience. Prior studies suggest that gamma activity may play a role in perceptual mechanisms, but design limitations raise concerns. Thus, controversy exists as to the hypothesis that gamma activity is necessary for perceptual awareness. In addition, controversy exists as to whether the primary sensory cortices are involved directly in the mechanisms of conscious perception or just in processes prior to conscious awareness. OBJECTIVE: To investigate the relation of gamma coherence and perception. METHODS: Digital intracranial electrocorticographic recordings from implanted electrodes were obtained in six patients with intractable epilepsy during a simple somatosensory detection task for near-threshold stimuli applied to the contralateral hand. Signal analyses were then conducted using a quantitative approach that employed two-way Hanning digital bandpass filters to compute running correlations across pairs of channels at various time epochs for each patient and each perception state across multiple bandwidths. RESULTS: Gamma coherence occurs in the primary somatosensory cortex approximately 150 to 300 milliseconds after contralateral hand stimuli that are perceived, but not for nonperceived stimuli, which did not differ in character/intensity or early somatosensory evoked potentials. CONCLUSION: The results are consistent with the possible direct involvement of primary sensory cortex in elemental awareness and with a role for gamma coherence in conscious perception.

Adult↗
PubMed1993

Effects of nitric oxide synthase inhibition on regional cerebral blood flow and vascular resistance in conscious and isoflurane-anesthetized rats.

Nitric oxide is an important regulator of the regional cerebral vascular tone. We compared the magnitude of nitric oxide-related changes in the vascular tone by studying the regional cerebral blood flow (rCBF) and vascular resistance in conscious and isoflurane-anesthetized rats by using a nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). In the conscious group (n = 12), after cannulation of a femoral artery and two veins under isoflurane anesthesia, rats were allowed to remain awake for 90 min. In the anesthetized group (n = 18), rats were anesthetized with 2% isoflurane and mechanically ventilated. Six rats in each group were treated with L-NAME (2 mg.kg-1 x min-1 for 30 min) or saline. For the remaining rats in the isoflurane-anesthetized group (n = 6), arterial blood pressure was increased by phenylephrine infusion to the same level as that in the L-NAME-treated, isoflurane-anesthetized rats. Regional vascular resistance was determined by the ratio of mean arterial blood pressure and rCBF which was measured by [14C]iodoantipyrine. L-NAME significantly increased mean arterial blood pressure in both the conscious (123 to 158 mm Hg) and anesthetized (82 to 144 mm Hg) rats. Regional vascular resistance increased significantly in all 12 brain regions studied with the average value increasing from 1.19 +/- 0.33 mm Hg.mL-1 x min x 100 g to 2.22 +/- 0.48 (P < 0.0001) in the conscious and from 0.78 +/- 0.27 to 1.61 +/- 0.48 (P < 0.0001) in the isoflurane-anesthetized rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗
PubMed2003

Changes in consciousness, conceptual memory, and quantitative electroencephalographical measures during recovery from sevoflurane- and remifentanil-based anesthesia.

UNLABELLED: It is unclear whether opioid-induced changes in electroencephalogram (EEG) or auditory evoked potentials (AEPs) reliably correspond with consciousness. We examined the correlation between 1) the clinically assessed state of consciousness, 2) implicit and explicit memory (by use of word pairs), and 3) various measures of EEG and AEP-bispectral index (BIS), A-Line ARX AEP index, spectral entropy, and entropy of the singular value decomposition (SVDEN; a measure of the complexity of the EEG). We studied 21 women during a two-stage awakening (sevoflurane washout followed by remifentanil washout) after anesthesia for gynecological surgery. All were amnesic, and 19 were unresponsive to verbal command with remifentanil alone. In six patients, BIS decreased paradoxically as the remifentanil concentration decreased; this was caused by a low-amplitude EEG, which was misinterpreted by the Aspect algorithm as burst suppression. Most of the EEG/AEP variables were sensitive to the decrease in sevoflurane and the recovery of consciousness, but not to the effects of decreasing remifentanil concentrations. SVDEN was the only variable that demonstrated significant increases for both the sevoflurane and remifentanil washout phases. With the prediction probability statistic during remifentanil washout, SVDEN = 0.79, spectral entropy = 0.81, A-Line ARX AEP index = 0.63, and BIS = 0.58. Entropy measures appear to be worthy of further clinical evaluation in a larger series of patients. SVDEN may be a useful variable for assessing anesthetic and analgesic effects on the central nervous system. IMPLICATIONS: During the recovery phase from a remifentanil-based anesthetic, the bispectral index is not reliably predictive of the depth of consciousness, because of suppression ratio artifacts. Entropy measures of the electroencephalogram show promise, but there is still no gold standard to estimate anesthetic depth.

Adult↗
PubMed2005

Noninvasive positive pressure ventilation in patients with acute exacerbations of COPD and varying levels of consciousness.

STUDY OBJECTIVES: A severely altered level of consciousness (ALC) has been considered a contraindication to noninvasive positive pressure ventilation (NPPV). We compared the clinical outcome of patients with acute respiratory failure (ARF) due to COPD exacerbations and different degrees of ALC. DESIGN: A 5-year case-control study with a prospective data collection. SETTING: Respiratory Monitoring Unit. PATIENTS: Eighty of 153 consecutive COPD patients requiring NPPV for ARF were divided into four groups, which were carefully matched for the main physiologic variables, according to the level of consciousness assessed with the Kelly-Matthay Score, in which 1 is normal (control subjects) and 6 is severely impaired. MEASUREMENT AND RESULTS: Changes from baseline in arterial blood gas (ABG) levels and Kelly score, the rate and causes of NPPV failure, the rate of nosocomial pneumonia, and the 90-day mortality rate were compared. NPPV significantly improved ABG levels and Kelly score in all groups after 1 to 2 h. NPPV failure (Kelly score 1 = 15%; Kelly score 2 = 25%; Kelly score 3 = 30%; Kelly score > 3 = 45%) and 90-day mortality rate (Kelly score 1 = 20%; Kelly score 2 = 35%; Kelly score 3 = 35%; Kelly score > 3 = 50%) significantly increased with the worsening of the level of consciousness. Using a multivariate analysis, the acute nonrespiratory component of the acute physiology and chronic health evaluation (APACHE) III score, and baseline pH independently predicted baseline Kelly score. After 1 to 2 h of NPPV, changes in the Kelly score were associated with those in pH. No correlation was found with Pa(CO2). CONCLUSIONS: This study confirms that NPPV may be successfully applied to patients experiencing COPD exacerbations with milder ALCs, whereas the rate of failure in patients with severely ALCs (ie, Kelly score > 3) is higher, even though better than expected, so that an initial and cautious attempt with NPPV may be performed even in this latter group. Changes in the level of consciousness induced by NPPV are not correlated with those in Pa(CO2).

Acid-Base Imbalance↗
PubMed1999

Sigmund Freud and the Crick-Koch hypothesis. A footnote to the history of consciousness studies.

The author describes Crick and Koch's recently developed theory of the neurophysiological basis of consciousness as synchronised neural oscillations. The thesis that neural oscillations provide the neurophysiological basis for consciousness was anticipated by Sigmund Freud in his 1895 'Project for a scientific psychology'. Freud attempted to solve his neuropsychological 'problem of quality' by means of the hypothesis that information concerning conscious sensory qualities is transmitted through the mental apparatus by means of neural 'periods'. Freud believed that information carried by neural oscillations would proliferate across 'contact-barriers' (synapses) without inhibition. Freud's theory thus appears to imply that synchronised neural oscillations are an important component of the neurophysiological basis of consciousness. It is possible that Freud's thesis was developed in response to the experimental research of the American neuroscientist M. M. Garver.

Austria↗
PubMed1990

[Life style and right to clean air in public places (RCA) (Part 2). The relationship between life style and the aspect of knowledge level of the consciousness towards smoking regulations among employees].

The right to clean air in public places (RCA) is a useful indicator of health consciousness. We surveyed the life style and consciousness towards RCA among employees working at the head office of a major company in Osaka, and examined the relationship between life style and knowledge aspect of RCA, one of the three aspects of consciousness towards RCA. Knowledge on laws concerning smoking regulations in public places was classified into two categories. One was knowledge on laws concerning general matters and the other was knowledge on laws concerning concrete and specific matters. Therefore, there are two kinds of relationship; the relationship between life style and knowledge on laws concerning general matters and the relationship between life style and knowledge on laws concerning concrete matters. These two relationships were examined with statistical procedures. Mean scores of knowledge on laws of subgroups divided by HPI score (POOR, MODERATE and GOOD) within groups divided by age and sex ("M. smoker," "M. nonsmoker" and "F. nonsmoker") were compared by t-test. Life style related to knowledge score was checked by correlation coefficient. The following results were obtained. (1) Relationship between life style and knowledge on laws concerning general matters Knowledge scores and their age-adjusted scores of MODERATE groups were the lowest among the 3 groups ("M. smoker," "M. nonsmoker," "F. nonsmoker"). This set of questions was designed to measure the knowledge level on laws concerning general matters. One would have abundant knowledge if one is health-conscious. In other words, those who do many things beneficial to physical health and have a high HPI have a wealth of knowledge on laws concerning smoking regulations on general matters. In the case of the employees, MODERATE groups were less health-oriented than others ("POOR," "GOOD") within the 3 groups ("M. smoker," "M. nonsmoker," "F. nonsmoker"). (2) Relationship between life style and knowledge on laws concerning concrete matters This set of questions was designed to measure the knowledge on laws concerning concrete and specific matters. To attain high scores, it is necessary to have more smoking experiences in various types of indoor places. POOR group of "M. smoker" and MODERATE groups of "M. nonsmoker" and "F. nonsmoker" had high knowledge scores. They were considered to have greater opportunities to visit public places where smoking is permitted (for example, bars) irrespective of their smoking status.

Adult↗
PubMed2005

Altered states of consciousness, dissociation, and dream recall.

In a sample of 71 medical students, dream recall frequency was positively correlated with proneness to altered states of consciousness (r = .26) measured by the State of Mind and Consciousness Questionnaire and dissociation (r = .29) measured by the Dissociative Experiences Scale II. A regression analysis, however, yielded neither altered states of consciousness nor dissociation, sex, or age to be significant predictors of dream recall frequency. Among women dream recall frequency was associated with proneness to dissociation; among men it was correlated with proneness to altered states of consciousness.

Adolescent↗
PubMed1976

The "consciousness problem" is not the problem.

Although the concept of consciousness is not necessary for the behavioral scientist, it is closely related to a number of psychological concepts that are generally believed to be necessary. Consciousness may be defined as the very short-term memory of a just-completed perceptual act. It may thus be understood as a psychological consequence of psychological antecedents. The question of how brain processes result in consciousness is a misleading one and should be replaced by questions concerning the relationships between the brain and perception, memory, and the other psychological processes that precede consciousness.

Arousal↗
PubMed1979

Perception: a model comprising two modes of consciousness.

A model of human perception is proposed in which conscious awareness is assumed to be the result of two separate mechanisms each involving consciousness, one outer, sensori-produced, and one inner, conceptual. By mediation of flexible memory representations the sensory data of the outer consciousness give rise to a matched "copy" in the inner consciousness which conceptually organizes the former and also serves as input to the memory store. The model is applied to some perceptual problems in vision such as ambiguous stimuli, subjective contours, space perception, a case of metacontrast, and subliminal perception.

Awareness↗
PubMed1989

Man's triune conscious mind.

In a previously presented perceptual model perception was assumed to be the result of two separate but coupled modes of consciousness, one sensory-based or outer and one memory-based or inner. Evidence was found for the assumption that the outer mode of consciousness is related to the primary projection areas of the sensory cortices. In the present paper the perceptual model is further integrated with the cognitive system while considering neuropsychological aspects. The two perceptual modes of consciousness, and one mode related to the experience of feelings, are considered to be the consciousness outlets of three functionally and physiologically distinguishable minds which cooperate or compete in the control of man's behavior.

Attention↗
PubMedDate not supplied

Dynamic systems theory approach to consciousness.

The review of the main existing approaches to consciousness in the literature indicates that consciousness is multileveled and that humans have an ability to experience a wide range of its various states. The common views of the main approaches to consciousness are identified and considered in a three-dimensional model of states of consciousness developed by Kokoszka. This model is then described and discussed using a mathematical terms of dynamic systems theory. Since mathematics is an accepted tool for the description of the physical world, the congruence of psychological and mathematical models is understood as a meaningful support to the psychological one. Connections of the models with artificial neural networks and some applications in psychology are considered.

Consciousness↗