Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Consciousness”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

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↗
PubMed2004

[What is impaired consciousness? Revisiting impaired consciousness as psychiatric concept].

For decades, psychiatrists have considered that concepts of impaired consciousness in the study of psychiatry were inconsistent with those applied in the field of neurology, in which the usefulness of the concept of consciousness has long been seriously doubted. Gloor concluded that the concept of consciousness does not further the understanding of seizure mechanisms or brain function, which is the current representative opinion of most epileptologists. Loss of consciousness tends to be reduced to aggregates of individual impairments of higher cognitive functions, and the concept of consciousness is preferably avoided by neurologists by assigning various behavioral disturbances during disturbed consciousness to particular neuropsychological centers. In contrast, psychiatrists, especially those in Europe, are more likely to include phenomena involving problems related to phenomenological intentionality in impaired consciousness. For the present study, we first divided consciousness into vigilance and recursive consciousness, and then attempted to determine what kind of impaired consciousness would be an ideal candidate to represent pure disturbance of recursive consciousness. Then, 4 patients, 1 each with pure amnestic states followed immediately by complex partial seizures, an akinetic mutistic state caused by absence status, and mental diplopia as a manifestation of postictal psychosis, as well as a patient with Alzheimer's disease who gracefully performed Japanese tea ceremony, were studied. Based on our findings, we concluded that impaired consciousness as a generic term in general medicine does not indicate any unitary entity corresponding to some well-demarcated physiological function or constitute a base from which recursive consciousness emerges as a superstructure. From that, we stressed that a pure form of impairment of recursive consciousness could occur without the impaired consciousness named generically in general medicine. Second, following observation of an additional 3 cases, descriptions of naissance of the first word (taken from the autobiography of Helen Keller), visual object agnosia, and chronic schizophrenia with schizophasia were discussed to examine the relationship between impairments of recursive consciousness and semantic generation dysfunction. Attempts to bridge semantic generation and recursive consciousness, performed by psychopathologists such as Bin Kimura and Hiroyuki Koide, were also briefly discussed. In light of these case presentations and related discussions, we re-examined traditional theories of impaired consciousness, including Mayer-Gross's Gestalt theory, later replaced by Conrad and Henri Ey's theory related to intentionality. Furthermore, we attempted to link Denett's theory of consciousness to those traditional theories as well as to our own postulations, and neuropsychological data such as those of implicit memory and blindsight. Finally, the significance of Freud's unconsciousness in the framework of neuroscience was discussed.

Adult↗
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↗
PubMed2006

Consciousness and altered consciousness.

The notion of consciousness in the English scientific literature denotes a global ability to consciously perform elementary and intellectual tasks, to reason, plan, judge and retrieve information as well as the awareness of these functions belonging to the self, that is, being self-aware. consciousness can also be defined as continuous awareness of the external and internal environment, of the past and the present. The meaning of consciousness is different in various languages, but it invariably includes, the conscious person is capable to learn, retrieve and use information. Disturbance or loss of consciousness in the Hungarian medical language indicates decreased alertness or arousability rather than the impairment of the complex mental ability. Awareness denotes the spiritual process of perception and analysis of stimuli from the inner and external world. Alertness is a prerequisite of awareness. Clinical observations suggest that the lesions of specific structures of the brain may lead to specific malfunction of consciousness, therefore, consciousness must be the product of neural activity. "Higher functions" of human mental ability have been ascribed to the prefrontal and parietal association cortices. The paleocerebrum, limbic system and their connections have been considered to be the center of emotions, feelings, attention, motivation and autonomic functions. Recent evidence indicates that these phylogenetically ancient structures play an important role in the processes of acquiring, storing and retrieving information. The hippocampus has a key role in regulating memory, learning, emotion and motivation. Impaired consciousness in the neurological practice is classified based on tests for conscious behavior and by analyzing the following responses: 1. elementary reactions to sensory stimuli--these are impaired in hypnoid unconsciousness, 2. intellectual reactions to cognitive stimuli--these indicate the impairment of cognitive contents in non-hypnoid unconsciousness. Obviously, disturbance of elementary reactions related to alertness and disturbance of intellectual performance overlap. In conditions with reduced ability to react to or to perceive external stimuli the cognitive disturbance of consciousness cannot fully be explored.

Adult↗
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↗
PubMed2004

Do neural correlates of consciousness cause conscious states?

Neural correlates of consciousness (NCCs) have been defined as neural systems and states of those systems, which are correlated with certain states of consciousness and which are minimally sufficient for these states of consciousness to occur. Here, it is discussed whether based on the identification of a NCC one may claim that this neural correlate causes the corresponding state of consciousness. In a strict sense, neural states and corresponding states of consciousness should occur simultaneously according to the definition of NCCs. However, two causally related events should occur consecutively in time according to the general view. Thus, within the NCC framework the question of a causal psychoneural relationship is only valid under the premise of a small and practically unobservable time shift between neural states and corresponding states of consciousness. The term causality is usually applied either in the sense of efficient causation or in the sense of explanatory causation. Efficient causality addresses the physical relation of two events and the criterion of an energy exchange between both events. Explanatory causality, on the other hand, refers to the law-like character of the conjoined occurrence of two events. Under a dualistic point of view, the interpretation that neural states effectively cause consciousness would not be justified, since effective causation, as understood in physical sciences, should be associated with energy transfer. But such an energy transfer between the domain of consciousness and the neural domain would violate presently accepted physical laws. Therefore, it is argued that one may state that neural states cause states of consciousness only in the broad sense of explanatory causality with regard to the observation of a law-like psychoneural relation. Within the viewpoint of identity theory, however, one would rather claim that certain states of consciousness basically are neural states.

Causality↗
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↗
PubMed2005

The minimally conscious state: defining the borders of consciousness.

There is no agreement as to where the limits of consciousness lie, or even if these putative borders exist. Problems inherent to the study of consciousness continue to confound efforts to establish a universally accepted theory of consciousness. Consequently, clinical definitions of consciousness and unconsciousness are unavoidably arbitrary. Recently, a condition of severely altered consciousness has been described, which characterizes the borderzone between the vegetative state and so-called "normal" consciousness. This condition, referred to as the minimally conscious state (MCS), is distinguished from the vegetative state by the presence of minimal but clearly discernible behavioral evidence of self or environmental awareness. This chapter reviews the diagnostic criteria, pathophysiology, prognostic relevance, neurobehavioral assessment procedures and treatment implications associated with MCS.

Brain↗
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

Cardiovascular effects of intravenous pentazocine and cyclazocine in conscious, curarized-conscious, and anesthetized dogs.

The cardiovascular effects of intravenous pentazocine and cyclazocine in dogs were studied under conscious, curarized-conscious (paralyzed by gallamine), and anesthetized states. In the conscious state, blood pressure and heart rate were dose-dependently increased by pentazocine (1, 2, 3 mg/kg) and to a lesser extent by cyclazocine (0.3 mg/kg). In all subsequent experiments on dogs, the results were obtained using 3 mg/kg pentazocine and 0.3 mg/kg cyclazocine. Pentazocine accelerated breathing, peaking at about 10 min, whereas cyclazocine reduced breathing to a minimum in 1 min, followed by a gradual recovery thereafter. In the curarized-conscious state, the blood pressure response to pentazocine was biphasic, namely an initial decrease followed by an increase; chronotrophic activity was stimulated. Pretreatment with either ganglionic or alpha andrenergic blocking agents not only significantly antagonized the pressory responses to the drug but also potentiated the initial decreases in blood pressure and unmasked a bradycardic component, but these parameters were not altered by 0.3 mg/kg naxalone. In open-chest anesthetized dogs, blood pressure, heart rate, contractility, and mean peripheral vascular resistance were simultaneously decreased by both pentazocine and cyclazocine, initially accompanied by increases in aortic blood flow. During the later stages of drug action, only the blood pressure and contractility were increased above control levels (biphasic effect). A comparison of blood pressure and heart rate responses to pentazocine in dogs kept under differing experimental conditions revealed that conscious dogs were more sensitive than curarized conscious and anesthetized animals to pentazocine action. In isolated guinea pig atria, the effect of adrenaline (0.1, 0.3, or 1 mg/mL) on the spontaneous breathing rate was significantly augmented by 10 mg/mL pentazocine (p < 0.02 for 0.3 g/mL; p < 0.01 for 0.1 g/mL adrenaline). In dogs, however, adrenaline (1 mg/kg)-induced increases in heart contractility, aortic blood flow, and blood pressure remained almost unaltered in the presence of pentazocine. We concluded that the abovementioned cardiovascular responses to pentazocine and cyclazocine are a consequence of the sum of the two following opposing effects: (i) an indirect reflex activation of sympathetic neuromediation in the periphery, and (ii) a direct membrane effect on the heart leading to bradycardia and a depression in myocardial contractility.

Anesthesia↗
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↗
PubMed2006

Human development VIII: a theory of "deep" quantum chemistry and cell consciousness: quantum chemistry controls genes and biochemistry to give cells and higher organisms consciousness and complex behavior.

Deep quantum chemistry is a theory of deeply structured quantum fields carrying the biological information of the cell, making it able to remember, intend, represent the inner and outer world for comparison, understand what it "sees", and make choices on its structure, form, behavior and division. We suggest that deep quantum chemistry gives the cell consciousness and all the qualities and abilities related to consciousness. We use geometric symbolism, which is a pre-mathematical and philosophical approach to problems that cannot yet be handled mathematically. Using Occam's razor we have started with the simplest model that works; we presume this to be a many-dimensional, spiral fractal. We suggest that all the electrons of the large biological molecules' orbitals make one huge "cell-orbital", which is structured according to the spiral fractal nature of quantum fields. Consciousness of single cells, multi cellular structures as e.g. organs, multi-cellular organisms and multi-individual colonies (like ants) and human societies can thus be explained by deep quantum chemistry. When biochemical activity is strictly controlled by the quantum-mechanical super-orbital of the cell, this orbital can deliver energetic quanta as biological information, distributed through many fractal levels of the cell to guide form and behavior of an individual single or a multi-cellular organism. The top level of information is the consciousness of the cell or organism, which controls all the biochemical processes. By this speculative work inspired by Penrose and Hameroff we hope to inspire other researchers to formulate more strict and mathematically correct hypothesis on the complex and coherence nature of matter, life and consciousness.

Behavior↗
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↗