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PubMed1998

[Perception, mimesis and consciousness].

Questions as to the fundamentals of "consciousness" are envisaged, first of all, from the viewpoint of quantifying experiments on visual perception in humans, focussed on "internal censorship", the role of intrapsychic mechanisms processing and correcting perception, and secondly based on recent theories on "mimesis" in the sense of R. Girard's concept of psychosocial transfer of aims and values between humans. The paper demonstrates a convergence between these two strategies of understanding, pointing to the view that "consciousness" may be interpreted as the performance of the intrapsychic "translation" between "cognitive" and "assessing" (or "valuating") emotional processes.

Consciousness↗
PubMed1993

[Quantifying pathological disorders of consciousness. Reliability criteria, aims, feasibility].

Within a survey of coma scales we distinguish scales of clinical findings (Glasgow Coma Scale [GCS], Glasgow Liège Scale [GLS], Innsbruck Coma Scale [ICS], Comprehensive Level of Consciousness Scale [CLOCS]), grading tests (Vigilance Scale [VS], Funktionspsychose-Skala-B [FPBS-B]) and level-scales (Reaction-Level-Scale [RLS-85], Munich Coma Scale [MCS]). With regard to the purpose we differentiate a classification of depth, the prediction of prognosis and the monitoring of changes. For the purpose of classification of depth, the RLS-85 because of its superior objectivity is preferable, but the GCS is of comparable validity and more widely used. The GLS differentiates the deeper states of coma better than either of these because brainstem-reflexes in cranio-caudal order are added. Within the prediction of prognosis all coma-scales have only limited validity and for the purpose of resource economy require additional criteria in the individual case. For the purpose of monitoring changes the level-scales primarily do not fit, the GCS is not sensitive enough. The Glasgow-Cologne-List is better suited; it is more than one-dimensional, but can be expressed through the GCS numbers for comparative purposes. The ICS is not widely used and the prognostic validity has not been proven to the same extent. The Glasgow-Cologne-List could be amplified for the less severe disturbances of consciousness according to Price (32,33), and for the lower levels according to the GLS (2,3,4). In both cases the expense is slightly higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Damage, Chronic↗
PubMed1997

The irreducible perspectives of consciousness.

I argue that there is no mind-brain problem but rather that there are irreducible subjective-objective problems. These include the difference between "inside" and "outside" perspectives on neural states, the creation of subjective neural states with objectified outside objects, and awareness of the self as an object in the world. The origin of consciousness is traced to the development of meaning states, and I demonstrate how differing perspectives related to these states are mutually irreducible. For instance, neural states are spatiotemporally distributed when observed from the outside, while mental states are unified when experienced from the inside; from the inside neural states are experienced as outside of themselves; and qualia have a material reality only from the inside. Rather than positing a special substance or immaterial process theory of consciousness, it is argued that the apparent immateriality of mind is an artifact of the nature of the phenomenon and of the process of observation itself.

Brain↗
PubMed1997

Freud and consciousness: the first one hundred years of neuropsychodynamics in theory and clinical practice.

Psychoanalysis emerged out of Freud's neuropsychologic studies of consciousness and cognition. This article describes the historical development of neuropsychodynamic theories of consciousness and personality, and traces their application to several neuropsychiatric syndromes of intense contemporary clinical interest. Even in this era of narrow syndromic differentiation and classification, an appeal is made for a more integrated approach to the evaluation and treatment of neurobehavioral syndromes.

Consciousness↗
PubMed1997

Recent work on consciousness: philosophical, theoretical, and empirical.

Broad-spectrum philosophical resistance to physicalist accounts of conscious awareness has condensed around a single and clearly identified line of argument. Philosophical analysis and criticism of that line of argument has also begun to crystallize. The nature of that criticism coheres with certain theoretical ideas from cognitive neuroscience that attempt to address both the existence and the contents of consciousness. Also, experimental evidence has recently begun to emerge that will serve both to constrain and to inspire such theorizing. The present article attempts to summarize the situation.

Awareness↗
PubMed1986

Lateral displacement of the brain and level of consciousness in patients with an acute hemispheral mass.

Brain-tissue shifts associated with drowsiness, stupor, and coma were studied by clinical examination and CT scanning in 24 patients with acute unilateral cerebral masses. Studies were performed soon after the appearance of the mass to detect the earliest CT changes associated with depression of consciousness. Contrary to traditional concepts, early depression of the level of alertness corresponded to distortion of the brain by horizontal displacement rather than transtentorial herniation with brain-stem compression. Horizontal displacement of the pineal body of 0 to 3 mm from the midline was associated with alertness, 3 to 4 mm with drowsiness, 6 to 8.5 mm with stupor, and 8 to 13 mm with coma. Moreover, drowsy or stuporous patients and some comatose patients had widened cisterns between the tentorial edge and the midbrain on the side of the mass, suggesting that the space was not filled by herniated medial temporal lobe. Downward displacement of the pineal body, indicating central transtentorial herniation, did not occur. Compression of one hemisphere by the other anteriorly (transfalcial herniation) was inconsistently related to alertness, though very large anterior displacements may have caused stupor in some patients. Current concepts of the pathoanatomical nature of depressed consciousness, based on pathological material obtained well after clinical examinations, may require revision, because they do not reflect early brain-tissue distortions.

Brain↗
PubMed2005

Repression of unconscious information by conscious processing: evidence from affective blindsight induced by transcranial magnetic stimulation.

Some patients with a lesion to the primary visual cortex (V1) show "blindsight": the remarkable ability to guess correctly about attributes of stimuli presented to the blind hemifield. Here, we show that blindsight can be induced in normal observers by using transcranial magnetic stimulation of the occipital cortex but exclusively for the affective content of unseen stimuli. Surprisingly, access to the affective content of stimuli disappears upon prolonged task training or when stimulus visibility increases, allegedly increasing the subjects' confidence in their overall performance. This finding suggests that availability of conscious information suppresses access to unconscious information, supporting the idea of consciousness as a repressant of unconscious tendencies.

Adult↗
PubMed2003

Naturalizing consciousness: a theoretical framework.

Consciousness has a number of apparently disparate properties, some of which seem to be highly complex and even inaccessible to outside observation. To place these properties within a biological framework requires a theory based on a set of evolutionary and developmental principles. This paper describes such a theory, which aims to provide a unifying account of conscious phenomena.

Consciousness↗
PubMed1992

On the definition of the concepts thinking, consciousness, and conscience.

A complex system (CS) is defined as a set of elements, with connections between them, singled out of the environment, capable of getting information from the environment, capable of making decisions (i.e., of choosing between alternatives), and having purposefulness (i.e., an urge towards preferable states or other goals). Thinking is a process that takes place (or which can take place) in some of the CS and consists of (i) receiving information from the environment (and from itself), (ii) memorizing the information, (iii) the subconscious, and (iv) consciousness. Life is a process that takes place in some CS and consists of functions i and ii, as well as (v) reproduction with passing of hereditary information to progeny, and (vi) oriented energy and matter exchange with the environment sufficient for the maintenance of all life processes. Memory is a complex of processes of placing information in memory banks, keeping it there, and producing it according to prescriptions available in the system or to inquiries arising in it. Consciousness is a process of realization by the thinking CS of some set of algorithms consisting of the comparison of its knowledge, intentions, decisions, and actions with reality--i.e., with accumulated and continuously received internal and external information. Conscience is a realization of an algorithm of good and evil pattern recognition.

Artificial Intelligence↗
PubMed1992

Quantum aspects of brain activity and the role of consciousness.

The relationship of brain activity to conscious intentions is considered on the basis of the functional microstructure of the cerebral cortex. Each incoming nerve impulse causes the emission of transmitter molecules by the process of exocytosis. Since exocytosis is a quantal phenomenon of the presynaptic vesicular grid with a probability much less than 1, we present a quantum mechanical model for it based on a tunneling process of the trigger mechanism. Consciousness manifests itself in mental intentions. The consequent voluntary actions become effective by momentary increases of the probability of vesicular emission in the thousands of synapses on each pyramidal cell by quantal selection.

Animals↗
PubMed2003

A hypothalamic digoxin-mediated model for conscious and subliminal perception.

The human hypothalamus produces an endogenous membrane (Na+)-K+ ATPase inhibitor digoxin. Digoxin can modulate multiple neurotransmitter systems. It can play a role in perceptual binding, focused attention and short term memory important in conscious perception. It can also mediate subliminal or quantal perception. A hypothalamic digoxin-mediated model for conscious and quantal perception is postulated.

Consciousness↗
PubMed2003

Feasibility of swallowing interventions for tracheostomized individuals with severely disordered consciousness following traumatic brain injury.

PRIMARY OBJECTIVE: To report the ability of 12 tracheostomized acute rehabilitation hospital inpatients with severely disordered consciousness post-traumatic brain injury (TBI) to participate in an objective swallowing assessment. RESEARCH DESIGN: Post hoc analysis of data from a larger, prospective blinded comparison study. METHODS AND PROCEDURES: Subjects completed a modified barium swallow (MBS) study. Food/drink and tracheostomy tube management recommendations were made. MAIN OUTCOMES AND RESULTS: All subjects participated successfully during an MBS. Post-MBS, 10 subjects began receiving small amounts of food and/or drink. Prior to hospital discharge, all subjects received some food and/or drink and were extubated. Subjects were deemed representative of this patient population and, from a swallowing perspective, other tracheostomized patient populations at the same facility. CONCLUSIONS: Clinicians should routinely consider tracheostomized, acute rehabilitation hospital inpatients with severely disordered consciousness post-TBI potential MBS candidates. Implications and continued research needs are discussed.

Adult↗
PubMed2006

Atlantoaxial subluxation with recurrent consciousness disturbance in a boy with Lesch-Nyhan syndrome.

UNLABELLED: Deficiency of the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT) may cause various clinical entities such as Lesch-Nyhan syndrome (LNS). A 9.5-y-old boy with the phenotypic features of LNS, including hyperuricaemia, choreoathetosis, self-mutilation and profound neurological dysfunction, was found to have HPRT deficiency. Normocytic anaemia, hyperuricaemia (uric acid 594.8 micromol/l) and microscopic haematuria with uric acid crystals were noted. Ultrasonography showed bilateral nephrocalcinosis and urinary bladder stones. In addition, he presented with three episodes of consciousness disturbance with limb paresis, possibly caused by atlantoaxial subluxation (AAS) with compression myelopathy. The diagnosis was made by the amount of residual enzyme activity and a single nucleotide substitution on the acceptor site region of intron 5 (IVS5-1 G-->C) of the HPRT gene, inherited from his asymptomatic mother. CONCLUSION: Lesch-Nyhan syndrome is a devastating sex-linked recessive disorder resulting from almost complete deficiency of the activity of HPRT. This report highlights the unusual AAS in a boy with LNS presenting recurrent consciousness change. The mutation described herein is a hitherto unreported splicing error leading to exon 6 skipping of the HPRT gene.

Atlanto-Axial Joint↗
PubMedDate not supplied

Recovery of consciousness and life expectancy of children in a vegetative state.

The vegetative state does occur in children and is most commonly due to acquired traumatic and non-traumatic injuries. However, neurometabolic and degenerative diseases, as well as certain developmental brain malformations such as anencephaly, can also cause this condition. There are limited data available in children concerning recovery of consciousness and function from the vegetative state as well as life expectancy. This review concentrates on these issues and is based primarily on the data published in the Multi-Society Task Force Report on PVS which was published in 1994 as well as other epidemiological studies. Children in a vegetative state do have a poor prognosis for recovery of consciousness and function and do have a shortened life expectancy. Further research is needed to better understand what variables might contribute to recovery and what therapies might be of benefit.

Adolescent↗
PubMedDate not supplied

Electrical treatment of reduced consciousness: experience with coma and Alzheimer's disease.

The right median nerve can be stimulated electrically to help arouse the central nervous system for persons with reduced levels of consciousness. The mechanisms of central action include increased cerebral blood flow and raised levels of dopamine. There is 11 years of experience in the USA of using nerve stimulation for acute coma after traumatic brain injury. There is a much longer period of experience by neurosurgeons in Japan with implanted electrodes on the cervical spinal cord for persons in the persistent vegetative state (PVS). But the use of right median nerve electrical stimulation (RMNS) for patients in the subacute and chronic phases of coma is relatively new. Surface electrical stimulation to treat anoxic brain injury as well as traumatic brain injury is evolving. Novel applications of electrical stimulation in Amsterdam have produced cognitive behavioural effects in persons with early and mid-stage Alzheimer's disease employing transcutaneous electrical nerve stimulation (TENS). Improvements in short-term memory and speech fluency have also been noted. Regardless of the aetiology of the coma or reduced level of awareness, electrical stimulation may serve as a catalyst to enhance central nervous system functions. It remains for the standard treatments and modalities to retrain the injured brain emerging from reduced levels of consciousness.

Acute Disease↗
PubMedDate not supplied

Considerations for the use of assistive technology in patients with impaired states of consciousness.

While there is limited literature addressing the application of assistive technology in patients in persistent vegetative state (PVS) and minimally conscious state (MCS), it is believed that it can assist with the assessment, diagnosis and treatment as well as management of these patients. The use of technology to assist in PVS and MCS is mostly limited to the application of simple binary switch devices to determine whether a motor response is consistent or otherwise. However, the application of such technology is often undermined due to a lack of established protocols for use by the multidisciplinary team (MDT), as well as a lack of available technical resources. Therefore the ongoing development of assessment instruments as well as effective outcome measures used by an MDT is imperative. This article aims to discuss some key aspects to consider in the use of assistive technology when assessing and treating people in impaired conscious states. Possible considerations and suggestions will be discussed through this paper and a case study will be used to demonstrate some of these interventions.

Adult↗
PubMed2005

Gonadectomy and androgen replacement alter cardiac performance in conscious adult male rats.

Gender disparities in cardiac function have been described. Yet the extent to which gender related differences in cardiac performance are due to the presence of sex-specific biological factors are unclear. We used a longitudinal study aimed at examining whether castration and androgen replacement affects cardiac performance in conscious adult male rats. Adult male rats were implanted with Piezoelectric transit-time gauges and radio telemetry devices to measure regional myocardial segment length and hemodynamic variables before and after castration and after androgen replacement. Androgen withdrawal accelerated average heart rates by 7% (p=0.010). Heart rate was lowered to intact values when androgens were restored to normal physiological levels (p=0.004). Mean arterial pressure was not affected by androgen deprivation and androgen replacement. However, androgen withdrawal produced a 40% decrease in the velocity of circumferential shortening and a 46% reduction in the rate of myocardial relaxation. Androgen supplementation completely restored contractile function. These results provide the first evidence that androgen withdrawal and androgen replacement produces dramatic alterations on cardiac performance in conscious animals and demonstrates the significance of androgens as a cardio-regulatory hormone in males. Sex steroids are likely contributors to gender-related differences in cardiac function.

Androgens↗
PubMed2005

Central actions of agmatine in conscious spontaneously hypertensive rats.

Agmatine (decarboxylated arginine) is an endogenous ligand at alpha-2 adrenergic and imidazoline nonadrenergic receptors. In conscious spontaneously hypertensive rats (SHRs), we have studied its central effects on cardiovascular function and its interaction with the second generation centrally acting antihypertensive agent, rilmenidine, and the reference imidazoline, clonidine, which are mixed alpha-2 adrenoceptor/imidazoline receptor agonists. Agmatine, when administered in low doses (30-100 microg/kg) into the fourth ventricle had no effect on blood pressure and caused an increase in heart rate. A higher dose of 1,000 microg/kg produced an adverse reaction in conscious SHRs and a marked and long-lasting increase in blood pressure. The effects of fourth ventricular rilmenidine (300 microg/kg) and clonidine (10 microg/kg) were equihypotensive and equibradycardic. The antihypertensive and bradycardic effects of rilmenidine were not reversed by cumulative intracisternal doses (30-100-300 microg/kg) of agmatine. The bradycardia obtained 20 min after intracisternal administration of clonidine in the fourth ventricle was reversed by 30 microg/kg agmatine. Only the highest dose of agmatine (1,000 microg/kg) did reverse the antihypertensive effects of rilmenidine and clonidine. Agmatine neither did mimic nor block the antihypertensive response to rilmenidine and clonidine at well-tolerated doses. Yet agmatine produced a small tachycardia at relatively low doses and was able to reverse the bradycardia induced by clonidine. Therefore, its affinity for alpha-2 adrenoceptors in vitro might partially explain its cardiovascular effects in vivo.

Agmatine↗