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At least 19 recordsLinked to original sources
PubMed1998

Beyond consciousness of external reality: a "who" system for consciousness of action and self-consciousness.

This paper offers a framework for consciousness of internal reality. Recent PET experiments are reviewed, showing partial overlap of cortical activation during self-produced actions and actions observed from other people. This overlap suggests that representations for actions may be shared by several individuals, a situation which creates a potential problem for correctly attributing an action to its agent. The neural conditions for correct agency judgments are thus assigned a key role in self/other distinction and self-consciousness. A series of behavioral experiments that demonstrate, in normal subjects, the poor monitoring of action-related signals and the difficulty in recognizing self-produced actions are described. In patients presenting delusions, this difficulty dramatically increases and actions become systematically misattributed. These results point to schizophrenia and related disorders as a paradigmatic alteration of a "Who?" system for self-consciousness.

Cerebral Cortex↗
PubMed1978

Consciousness and disturbances of consciousness.

The problem of consciousness is discussed briefly, including the contrary views of consciousness as a transcendental phenomenon and as an animistic fiction. Measurement of consciousness is possible only indirectly by means of quantitative assessment of accompanying behavioral deficits. Knowledge of the structural basis of consciousness is incomplete. The ascending reticular activating system (ARAS) is necessary for the maintenance of the state of consciousness. The monoamine and a great number of descending projections modulate the ARAS. The contents of consciousness depend also on telencephalic structures, primarily on the telencephalic cortex. Certain localized telencephalic lesions bring about disturbances of consciousness. The role of the corpus callosum in the problem of consciousness is discussed (one brain--two minds hypothesis). Then a classification of the various disturbances of consciousness is proposed. The term "disturbances of vigilance" is used for all disturbances of consciousness which are caused by a lesion in or a functional disorder of the ARAS or any of its modulating subsystems. The term "disturbances of the contents of consciousness" refers to disturbances of consciousness due to global or localized lesions or functional disorders of telencephalic structures. A list of characteristic features is given for each class of disturbances of consciousness.

Attention↗
PubMed1994

[Consciousness and self-consciousness as biological phenomena].

Can there be a generally accepted account of consciousness? Consciousness is the main aspect of the mind-body problem and has intrigued man since he achieved the awareness of his own existence and identity, i.e. since he became self-conscious. The topic of consciousness spans the efforts of the humanist and naturalist, psychological, theological and physiological thinking and research. During the last years an upsurge of both neurophysiological and philosophical interest has tried to outline the place of consciousness and self-consciousness in the order of nature. 'Without consciousness, the mind-body problem would be much less interesting. With consciousness it seems hopeless', Nagel (16) wrote. Our thesis, supported by a significant part of today's epistemology (which takes up the believes of several main physiologists from the last century up to now), is that the question of consciousness and the mind-body problem are systematically and scientifically insoluble because the mind is fated to remain intrinsically mysterious to us. Thus, even though consciousness and self-consciousness belong to the intrinsic characteristics of our everyday life and experience, they seem to remain indefinable and mysterious and, therefore, to fall outside the scope of rational inquiry, defying both scientific and philosophical investigation. This assumption does not mean that neurophysiological sciences are unfeasible, but it is just an inquiry into their methodologic and cognitive limits.

Awareness↗
PubMed2002

Re-representing consciousness: dissociations between experience and meta-consciousness.

A distinction is drawn between non-conscious (unexperienced), conscious (experienced), and meta-conscious (re-represented) mental processes. There is evidence for two types of dissociations between consciousness and meta-consciousness, the latter being defined as the intermittent explicit re-representation of the contents of consciousness. Temporal dissociations occur when an individual, who previously lacked meta-consciousness about the contents of consciousness, directs meta-consciousness towards those contents; for example, catching one's mind wandering during reading. Once meta-consciousness is triggered, translation dissociations can occur if the re-representation process misrepresents the original experience, such as when one verbally reflects on non-verbal experiences or takes stock of subtle or ambiguous experiences.

Journal Article↗
PubMed1987

The consciousness of being conscious.

Starting with the therapeutic advantage gained when insight acquires consciousness, an investigation of the nature and function of consciousness is undertaken. Consciousness is a state of awareness, having a range of higher mental functions serving a regulatory, controlling, and integrating role in mental activity. There are high levels of thinking, reality testing, experiencing, judging, anticipating; self-awareness and self-reflection enter into these controlling activities. Psychoanalysis has rightly been a science that studies the workings and contents of the unconscious portions of the mind. It has perhaps overlooked the important role that consciousness plays in ordinary life and in providing the levels of control and self-awareness individuals both experience and require. That pathology and disturbances of function may accompany normal states of consciousness as well as altered states of consciousness is a common clinical phenomenon. Psychoanalysis as a therapy widens the scope of the conscious control systems.

Awareness↗
PubMed2001

Automated responsiveness test (ART) predicts loss of consciousness and adverse physiologic responses during propofol conscious sedation.

BACKGROUND: The authors evaluated a device designed to provide conscious sedation with propofol (propofol-air), or propofol combined with 50% nitrous oxide (N2O; propofol-N2O). An element of this device is the automated responsiveness test (ART), a method for confirming that patients remain conscious. The authors tested the hypotheses that the ART predicts loss of consciousness and that failure to respond to the ART precedes sedation-induced respiratory or hemodynamic toxicity. METHODS: The protocol consisted of sequential 15-min cycles in 20 volunteers. After a 15-min control period, propofol was infused to an initial target effect-site concentration of 0.0 microg/ml with N2O or 1.5 microg/ml with air. Subsequently, the propofol target effect-site concentration was increased by a designated increment (0.25 and 0.5 microg/ml) and the process repeated. This sequence was continued until loss of consciousness, as defined by an Observer's Assessment of Alertness/Sedation (OAA/S) score of 10/20 or less, or until an adverse physiologic event was detected. RESULTS: The OAA/S score at which only 50% of the volunteers were able to respond to the ART (P50) during propofol-N2O was 11.1 of 20 (95% confidence interval [CI]: 10.6-11.8); the analogous P50 was 11.8 of 20 (95% CI: 11.4-12.3) with propofol-air. Failure to respond to the ART occurred at a plasma propofol concentration of 0.7 +/- 0.6 microg/ml with propofol-N2O and 1.6 +/- 0.6 microg/ml with propofol-air, whereas loss of consciousness occurred at 1.2 +/- 0.8 microg/ml and 1.9 +/- 0.7 microg/ml, respectively. There were no false-normal ART responses. CONCLUSION: The ART can guide individual titration of propofol because failure to respond to responsiveness testing precedes loss of consciousness and is not susceptible to false-normal responses. The use of N2O with propofol for conscious sedation decreases the predictive accuracy of the ART.

Adult↗
PubMed2003

Developmental aspects of consciousness: how much theory of mind do you need to be consciously aware?

When do children become consciously aware of events in the world? Five possible strategies are considered for their usefulness in determining the age in question. Three of these strategies ask when children show signs of engaging in activities for which conscious awareness seems necessary in adults (verbal communication, executive control, explicit memory), and two of the strategies consider when children have the ability to have the minimal form of higher-order thought necessary for access consciousness and phenomenal consciousness, respectively. The tentative answer to the guiding question is that children become consciously aware between 12 and 15 months (+/-3 months).

Awareness↗
PubMed1994

Propofol infusion and the suppression of consciousness: dose requirements to induce loss of consciousness and to suppress response to noxious and non-noxious stimuli.

We have defined the infusion dose requirements of propofol to suppress consciousness and response to a variety of graded non-noxious and noxious stimuli in 52 unpremedicated patients aged 16-40 yr and 32 patients aged 41-65 yr. They were allocated to receive one of five loading dose-infusion schemes designed to establish stable conditions covering the range from wakefulness, through sedation, to loss of consciousness and anaesthesia. At 10 and 20 min after the loading dose, each patient's response to a graded series of stimuli was recorded. Probit analysis was used to derive mean values (95% confidence interval) for the ED50 and ED95 (as final infusion rate) for loss of response to verbal command at 4.9 (4.7-5.1) mg kg-1 h-1 and 7.9 (7.3-8.8) mg kg-1 h-1, respectively, in the young group and 4.2 (4.0-4.4) mg kg-1 h-1 and 5.8 (5.4-6.4) mg kg-1 h-1, respectively, in the older group. In both groups the dose-response curves for suppression of proprioception, finger counting and perception of light touch in conscious patients were shifted to the left of the curves for loss of consciousness and eyelash reflex. Dose-response curves for noxious stimuli were shifted to the right of those for loss of consciousness.

Adolescent↗
PubMed1989

Brain shift, level of consciousness, and restoration of consciousness in patients with acute intracranial hematoma.

Recently, Ropper reported that horizontal brain shift caused by acute unilateral mass lesions correlated closely with consciousness, and suggested that recovery of consciousness was unlikely to occur after surgical evacuation if the shift was insufficient to explain the observed diminution of consciousness. The authors have sought to confirm the correlation of pineal shift with level of consciousness and to assess the prognostic value of brain shift measurements in a prospective study. Forty-six patients (19 with subdural hematoma, 14 with intracerebral hematoma, and 13 with epidural hematoma) were accrued to the study group consecutively. A correlation was found between a decrease in the level of consciousness and a significant increase in the mean lateral brain displacement at the pineal gland (from 3.8 to 7.0 mm) and septum (5.4 to 12.2 mm). When outcome was examined in patients who were stuporous or comatose on admission, a significant increase in septal shift was found among patients with a poor outcome, but there was no significant relationship between outcome and degree of pineal or aqueductal shift. A poor outcome was more likely with effacement of both perimesencephalic cisterns or the ipsilateral cistern, but not the contralateral cistern, although this difference did not reach statistical significance. These results do not substantiate the value of brain shift as an independent prognostic factor after evacuation of an acute unilateral mass lesion. The decision to operate and the determination of prognosis should be based rather on established criteria such as the clinical examination, age of the patient, and the mechanism of injury.

Acute Disease↗
PubMedDate not supplied

Health consciousness and health behavior: the application of a new health consciousness scale.

Self-consciousness has been an important trait in personality research. It seems logical to investigate whether health consciousness, involving a similar self-focusing, might operate in a parallel manner. To this end, I developed the Health Consciousness Scale (HCS), primarily by modifying items of the Self-Consciousness Scale, and also tested it for reliability and validity. My study found the HCS to contain four first-order factors: (1) Health Self-Consciousness, (2) Health Alertness, (3) Health Self-Monitoring, and (4) Health Involvement. I found these four first-order factors, along with the overall HCS second-order factor, to relate to a number of self-reported, health-associated behavioral variables. The study also included comparisons with the Health Locus-of-Control Scale and other measures.

Adult↗
PubMed1986

Concentrations of glycine and serine in cerebrospinal fluid during disturbed consciousness; a study of the therapeutic effect of thyrotropin-releasing hormone on the consciousness level.

The concentrations of aliphatic amino acids (glycine, serine, valine, threonine, alanine, leucine, isoleucine) in lumbar cerebrospinal fluid from patients with consciousness disturbances and normal controls were measured. Thyrotropin-releasing hormone (TRH) was administered to patients and the changes of levels of consciousness and amino acid concentrations were followed before and after TRH administration. The concentrations of glycine and serine from patients were significantly higher than those from controls; they returned to the control values with improvement of consciousness disturbances. The influence of TRH upon these amino acid concentrations was not observed. These results suggest that within the central nervous system, an alteration of the level of consciousness is associated with a distortion of glycine and serine metabolism and that TRH itself has no influence upon these amino acid concentrations.

Adolescent↗
PubMed1993

Demonstration of free radical generation in the "stunned" myocardium in the conscious dog and identification of major differences between conscious and open-chest dogs.

Conscious dogs undergoing a 15-min coronary occlusion were given alpha-phenyl N-tert-butyl nitrone (PBN) and the local coronary venous plasma was analyzed by electron paramagnetic resonance spectroscopy. A prolonged myocardial release of PBN radical adducts was observed, which exhibited a burst in the initial minutes of reflow (peaking at 3 min) and then abated but continued for 1-3 h after reperfusion. Computer simulation revealed the presence of at least two PBN adducts (aN = 15.2 G and a beta H = 6.0 G; aN = 14.6 G and a beta H = 3.0 G), both consistent with the trapping of secondary carbon-centered radicals. No appreciable PBN adduct production was observed when collateral flow exceeded 30-40% of nonischemic flow, indicating that a flow reduction of at least 60% is necessary to trigger free radical reactions. There was a direct relationship between the magnitude of PBN adduct production and the severity of contractile dysfunction (r = 0.77), suggesting that the radicals generated upon reperfusion play a causal role in the subsequent stunning. The total release of PBN adducts after 3 h of reperfusion following a 15-min coronary occlusion was found to be approximately five times greater in open-chest compared with conscious dogs; at the same time, the recovery of wall thickening was markedly less in open-chest dogs. This study represents the first application of spin trapping to a conscious animal model of myocardial ischemia. The results demonstrate (a) that free radicals are generated in the stunned myocardium in the absence of the artificial or abnormal conditions associated with previously used models (isolated hearts, open-chest preparations), and (b) that both the severity of postischemic dysfunction and the magnitude of the attendant free radical production are greatly exaggerated in the open-chest dog, implying that previous conclusions derived from this model may not be applicable to conscious animals or to humans. This investigation also provides a method to measure free radicals in awake animals.

Anesthesia, General↗
PubMed1994

[Neurology of consciousness and of consciousness disorders].

The two physiologic components of conscious behaviour, namely arousal (vigilance) and content of consciousness (presence of mind), may be affected differently, depending on the type and distribution of the underlying brain disease. Disturbance of arousal primarily affects wakefulness and awareness and leads to obtundation, stupor and coma. States of reduced arousal are caused by bilateral lesions of the so-called ascending reticular activating system (ARAS), which is situated in the upper brainstem and the paramedian diencephalon. If, on the other hand, cognitive and mnemic function are degraded, the contents of consciousness are disordered; depending on the extent of the disturbance, confusion, lethargy and, finally, a vegetative state ensues. The chronic vegetative state (coma vigil) describes a condition of total mental loss with preserved vegetative functions and arousal. Degraded cognitive and mnenic functions results from either toxic-metabolic or extensive structural disorders of the cerebral cortex, where the limbic and mesial frontal areas play a dominant role for conscious behaviour. If the function of extensive areas of both hemispheres is suddenly depressed, temporarily reduced arousal also results. In order to differentiate between toxic-metabolic and structural brain diseases, the motor reactions, the ocular and the pupillary reflexes must be examined apart from responsiveness.

Arousal↗
PubMed1989

[Clinical study of bruxism. Comparison of muscle activity during sleep between patients conscious of bruxism and those not conscious of the condition].

Bruxism has been considered to be one of the most important factors in accelerating the progression of established periodontal lesions. However the objective diagnostic method has not yet been established. At present, diagnosing bruxism might mainly be dependent on interview. The purpose of this study was to compare and analyze the differences in frequency and duration of bruxism between a group of patients conscious of the problem and a group not conscious of bruxism. After interviewing, the subjects were divided into two groups; 1) group A consisted of 8 subjects who were conscious of bruxism and 2) group B of 8 subjects who were not conscious of bruxism. The frequencies and durations of muscle activity during sleep at night were compared between groups A and B using EMG with a telemetric method. In the one-night observation, muscle activity supposed to be bruxism was observed in both groups. Significant differences in frequencies of muscle activity were not found between the two groups. A similar result was obtained in the durations of muscle activity. In a seven-day observation, muscle activity was seen in all three volunteers, although marked differences were not found among them. A long duration of muscle activity was found under conditions of physical or mental stress. The results of this study showed the difficulty of diagnosing bruxism by interview and the necessity of an objective method.

Bruxism↗
PubMed1997

Conscious sedation clinical guideline. Conscious Sedation Working Group, Medical Association of South Africa.

OBJECTIVE: The objective of this guideline is to promote safe conscious sedation technique. OUTCOME: (I) The use of safe conscious sedation techniques with endpoints of patient comfort and anxiolysis without loss of protective reflexes; (II) the use of drugs with a wide margin of safety that will protect against unintended oversedation. EVIDENCE: Based on existing consensus statements and some research reports. VALIDATION: Relevant organisations involved in conscious sedation were asked to select a representative to participate in the MASA Conscious Sedation Working Group. All participants represented organisations. The working group met in January 1996 to consider a draft guideline. The document was amended and circulated to working group members, representative organisations and 35 interested persons for endorsement and comment using a modified Delphi technique. All respondents endorsed the guideline (with or without minor corrections.) The national organisations endorsing the guidelines are listed. RECOMMENDATIONS: The use of drugs, equipment and personnel as directed in such a way that enhances the safety of the patient. Pre-sedation screening for at-risk patients. Intra-sedation monitoring, especially the use of a pulse oximeter. Post-sedation care and discharge instructions for the patient.

Procedural Sedation↗
PubMed1995

Tutorial commentary: surprisingly small subcortical structures are needed for the state of waking consciousness, while cortical projection areas seem to provide perceptual contents of consciousness.

The evidence can therefore be summarized as follows: (1) RF, nRt, and ILN activity seem to be necessary but not sufficient for conscious experience. (2) Stimulus representation in primary sensory projection areas also seems to be necessary but not sufficient for conscious perceptual experience (Weiskrantz, 1980). The simplest hypothesis is that both components are necessary and sufficient to support conscious perceptual experience.

Attention↗
PubMed1998

Epilepsy and recursive consciousness with special attention to Jackson's theory of consciousness.

John Hughlings Jackson's theory of consciousness has been reconsidered. The author stressed that his uniqueness as a neuroscientist lay in his keen interest in the recursive nature of human consciousness. Two clinical symptoms of interest to Jackson were discussed: recurrent utterances and mental diplopia. Recurrent utterances were believed to represent an exceptional state, in which the unconscious process in speech production, otherwise destined to be swept away automatically, became manifest and observable. Jackson regarded mental diplopia as a revelation of otherwise inaccessible duality of all healthy mental actions. Therefore, he supposed that the essence of recursive consciousness resided in a transformation of multiple, multidirectional, unconscious processes into a linear, unidirectional process.

Cognition↗