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PubMed2005

Pre- and poststimulus alpha rhythms are related to conscious visual perception: a high-resolution EEG study.

Conscious and unconscious visuospatial processes have been related to parietooccipital cortical activation as revealed by late visual-evoked potentials. Here the working hypothesis was that a specific pattern of pre- and poststimulus theta (about 4-6 Hz) and alpha (about 6-12 Hz) rhythms is differently represented during conscious compared with unconscious visuospatial processes. Electroencephalographic (EEG) data (128 channels) were recorded in normal adults during a visuospatial task. A cue stimulus appeared at the right or left (equal probability) monitor side for a "threshold time" inducing about 50% of correct recognitions. It was followed (2 s) by visual go stimuli at spatially congruent or incongruent position with reference to the cue location. Left (right) mouse button was clicked if the go stimulus appeared at the left (right) monitor side. Then, subjects said "seen" if they had detected the cue stimulus or "not seen" if missed (self-report). Sources of theta and alpha rhythms during seen and not seen EEG epochs were estimated by low-resolution electromagnetic brain topography software. Results showed that the prestimulus "low-band" (about 6-10 Hz) alpha rhythms in frontal, parietal, and occipital areas were stronger in power in the seen than in the not seen trials. After the visual stimulation, the power of the "high-band" (about 10-12 Hz) alpha rhythms in parietal and occipital areas decreased more in the seen than in the not seen trials. The present results suggest that visuospatial consciousness covary--presumably with a facilitatory effect--with the power of both pre- and poststimulus alpha rhythms.

Adult↗
PubMed1985

Stress ventricular function test in conscious, nonthoracotomised dogs to assess cardiac drug efficacy.

The measurement of left ventricular (LV) function is frequently performed in unconscious or thoracotomised animals in the resting state; these conditions may seriously affect the basal haemodynamic state. To assess myocardial function in conscious animals, a technique was developed to place a catheter across the atrial septum into the left ventricle without a thoracotomy. A stress ventricular function test (SVFT) was performed by raising the systemic blood pressure with methoxamine in the conscious dog. In order to demonstrate the effectiveness of the SVFT in the detection of a decrease in ventricular function, a SVFT was performed before and after the acute infusion of verapamil to determine resting and reserve LV function. A slope relating systolic aortic pressure to the LV end-diastolic pressure was obtained in 10 dogs using a low dose (0.005) and in four dogs a high dose (0.01 microgram X kg-1 X min-1) verapamil (V). The mean slope before V was 3.6 +/- 1.2 and after 2.0 +/- 0.92 (p less than 0.001). The day-to-day variability of the SVFT was less than 22% (coefficient of variability). The SVFT is a sensitive, reproducible method to assess resting and increased or decreased myocardial contractility and is useful in selecting appropriate doses of cardiac drugs to determine their effect on the myocardium during acute and chronic infusion studies in the conscious, nonthoracotomised dog.

Animals↗
PubMed1998

Effect of isoflurane on the auditory steady-state response and on consciousness in human volunteers.

BACKGROUND: The auditory steady state response (ASSR) is a sustained electrical response of the brain to auditory stimuli delivered at fast rates (30-50 responses/s). The aim of this study was to evaluate the effect of 0.26-0.50% isoflurane on the ASSR and on consciousness, defined as responsiveness to verbal commands. METHODS: Ten volunteers (21-31 yr) participated. Isoflurane was administered at three stable, end-tidal concentrations: 0.26%, 0.38%, and 0.50%. The ASSR in response to 18,000 stimuli (500-Hz tonebursts, 10 ms, 82-dB, the right ear, 35-45 bursts/s) was recorded from the vertex with reference to the right mastoid. Recordings were made during baseline, at each isoflurane concentration, and during recovery. RESULTS: The mean (SD) ASSR amplitudes were 0.32 (0.23) microV during baseline, 0.24 (0.17) microV during 0.26% isoflurane, 0.09 (0.05) microV during 0.38% isoflurane, 0.04 (0.03) microV during 0.50% isoflurane, and 0.29 (0.33) microV during recovery. The amplitude during baseline and recovery was larger than during 0.38% and 0.50% isoflurane (P < 0.001). The amplitude at 0.26% was larger than at the other concentrations (P < 0.025). The logarithm of the ASSR amplitude was related linearly to the concentration of isoflurane (r = 0.85; P < 0.0001). The prediction probability (Pk) for loss of consciousness was 0.95 for both ASSR and measured isoflurane concentration. An ASSR amplitude < 0.07 microV was always associated with unconsciousness. CONCLUSIONS: The ASSR is attenuated in a concentration-dependent manner by isoflurane. Suppression of consciousness and maximal attenuation of ASSR occur in the same isoflurane concentration range. Profound attenuation of ASSR appears to reflect unconsciousness, defined as unresponsiveness to verbal commands.

Acoustic Stimulation↗
PubMed2005

Increased gamma-band synchrony precedes switching of conscious perceptual objects in binocular rivalry.

Gamma-band neural synchrony has been proposed as a correlate of consciousness and as a solution for the binding problem. Research on visual working memory and the perception of coherent images in ambiguous figures supports this view. To test the relationship between perceptual consciousness and gamma synchrony, we recorded electroencephalogram activity while participants were presented with rivalling visual images to each eye. Participants pressed buttons to indicate which image they were perceiving, and response-locked phase-locking values (6-60 Hz) were calculated from the electroencephalogram time series. Results revealed transient bursts of increased global phase synchrony in the gamma-band peaking approximately 425 and approximately 260 ms preresponse. This suggests that global gamma synchrony is associated with the emergence of a coherent conscious percept.

Adolescent↗
PubMed2002

Intentionality and caring-healing consciousness: a practice of transpersonal nursing.

This article explicates some theoretical and scientific dimensions of intentionality and consciousness as a framework for transpersonal nursing. New connections are made between noetic sciences and transpersonal caring theory, both of which cultivate intentionality as a form of focused consciousness as a formal field of study. What emerges is Intentional Transpersonal Caring, whereby intentionality, consciousness, and universal energy-field are posited as the foundation of a caring moment, potentiating healing for both practitioner and patient. The theoretical and scientific are translated into the practical by a series of practice guidelines that activate intentionality into a living theory of transpersonal caring-healing praxis.

Consciousness↗
PubMed2000

A prospective population-based study of pediatric trauma patients with mild alterations in consciousness (Glasgow Coma Scale score of 13-14).

OBJECTIVE: Considerable controversy surrounds the appropriate evaluation of children with mild alterations in consciousness after closed head trauma (Glasgow Coma Scale [GCS] score of 13-14). The objective of the current study was to determine the incidence of intracranial lesions in pediatric patients with a field GCS score of 13 or 14 after closed head injuries. METHODS: The current study is a population-based, multicenter prospective study of all patients to whom emergency medical services responded during a 12-month period. The setting was urban Los Angeles County, encompassing a patient population of 2.3 million children, 13 designated trauma centers, and 94 receiving hospitals. RESULTS: In the pediatric age group (<15 yr old), 8488 patients were transported by emergency medical services for injuries. Of these, 209 had a documented field GCS score of 13 or 14. One hundred fifty-seven patients were taken to trauma centers, and 135 (86%) underwent computed tomography. Forty-three patients (27.4%) had abnormal results on computed tomographic scans, 30 (19.1%) had an intracranial hemorrhage, and 5 required an operative neurosurgical procedure for hematoma evacuation. Positive and negative predictive values of deteriorating mental status (0.500 and 0.844, respectively), loss of consciousness (0.173 and 0.809), cranial fracture (0.483 and 0.875, and extracranial injuries (0.205 and 0.814) were poor predictors of intracranial hemorrhage. CONCLUSION: Pediatric patients who have mild alterations in consciousness in the field have a significant incidence of intracranial injury. The great majority of these patients will not require operative intervention, but the implications of missing these hemorrhages can be severe for this subgroup of head-injured patients. Because clinical criteria and cranial x-rays are poor predictors of intracranial hemorrhage, it is recommended that all children with a GCS score of 13 or 14 routinely undergo screening via non-contrast-enhanced computed tomography.

Adolescent↗
PubMed2000

An extension to the hypothesis of the asynchrony of visual consciousness.

An existing hypothesis states that visual consciousness is made up of 'microconsciousnesses' occurring asynchronously in several sites of the visual system of the brain with no need for direct means of binding. We extend this hypothesis to define what qualifies a neural activity for generating an element of consciousness to distinguish it from one that does not. We argue that, for these separate neural activities to represent elements of a compound sense of consciousness, they each need the support of sites that unconsciously process an important attentional referent and that it is the commonality of such referents in differing sites which bring the microconsciousnesses together. We consider the broader implications of this extended hypothesis for other sensory modalities and mental imagery.

Consciousness↗
PubMed1998

The autonomy of the visual systems and the modularity of conscious vision.

Anatomical and physiological evidence shows that the primate visual brain consists of many distributed processing systems, acting in parallel. Psychophysical studies show that the activity in each of the parallel systems reaches its perceptual end-point at a different time, thus leading to a perceptual asynchrony in vision. This, together with clinical and human imaging evidence, suggests strongly that the processing systems are also perceptual systems and that the different processing-perceptual systems can act more or less autonomously. Moreover, activity in each can have a conscious correlate without necessarily involving activity in other visual systems. This leads us to conclude not only that visual consciousness is itself modular, reflecting the basic modular organization of the visual brain, but that the binding of cellular activity in the processing-perceptual systems is more properly thought of as a binding of the consciousnesses generated by each of them. It is this binding that gives us our integrated image of the visual world.

Animals↗
PubMed2004

Clinical holistic medicine: applied consciousness-based medicine.

Consciousness-based medicine is our term for a form of medical treatment that works by direct appeal to the consciousness of the patient, in contrast to modern biomedical treatment where drugs are used to affect body chemistry. With this concept, maybe we are (in a sense) turning back to the "old medicine", where the family physician was the all-concerned "old country doctor" who knew the child, the siblings, the parents, the family, and the village. In a series of papers on clinical holistic medicine, we would like to present the classic art of healing, where the physician works mostly with his hands, then show how the modern biomedical physician performs with biochemistry, and finally introduce consciousness-based medicine. Some of our questions will be: If you improve your quality of life, will you also improve your health? Will learning more about yourself bring more purpose in your life? Will finding someone to live with in a loving and mutually respectful relationship improve your health? Scientists and thinkers like Antonovsky, Frankl, Maslow, and Jung have pointed to love as a unique way to coherence in life, and thus to biological order and a better health. Several scientific studies have also suggested that patients who focus on improving their quality of life usually will not follow the general statistics for survival, since somehow other factors are at play, which sometimes you will find referred to as "exceptional".

Consciousness↗
PubMed2004

Is consciousness a gradual phenomenon? Evidence for an all-or-none bifurcation during the attentional blink.

Several theories of the neural correlates of consciousness assume that there is a continuum of perception, associated with a gradual change in the intensity of brain activation. But some models, considering reverberation of neural activity as necessary for conscious perception, predict a sharp nonlinear transition between unconscious and conscious processing. We asked participants to evaluate the visibility of target words on a continuous scale during the attentional blink, which is known to impede explicit reports. Participants used this continuous scale in an all-or-none fashion: Targets presented during the blink were either identified as well as targets presented outside the blink period or not detected at all. We suggest that a stochastic nonlinear bifurcation in neural activity underlies the all-or-none perception observed during the attentional blink.

Adult↗
PubMed1991

Effect of tolerance to glyceryl trinitrate on vascular responses in conscious rabbits.

1. The effect of tolerance to glyceryl trinitrate (GTN) on vasodilator and vasoconstrictor responses was examined in conscious rabbits and isolated rabbit aortic rings. 2. In conscious rabbits, depressor responses to 5 min infusions of GTN (10-40 micrograms/kg per min intravenously (i.v.)), sodium nitroprusside (SNP, 5-20 micrograms/kg per min i.v.) and acetylcholine (ACh, 3-12 micrograms/kg per min i.v.) were examined before and after transdermal treatment with GTN (20 mg/48 h). GTN pretreatment significantly attenuated GTN-induced depressor responses, indicating the development of tolerance, but did not affect the reductions in arterial pressure induced by SNP or ACh. 3. Similarly, aortic rings taken from GTN pretreated rabbits exhibited tolerance to GTN but the relaxant responses to SNP or the calcium ionophore A23187 were not affected. In the aortic rings from GTN-tolerant rabbits contractile responses to serotonin or the thromboxane-mimetic U46619 were significantly attenuated, in contrast to the responses to the alpha 1-adrenoceptor agonist phenylephrine (PE) which were significantly enhanced. 4. Similarly, in conscious rabbits, PE-induced increases in arterial pressure and hindlimb vascular resistance were significantly enhanced by GTN pretreatment but the responses to the alpha 2-adrenoceptor agonist BHT 920 were unaffected. 5. In conclusion, tolerance to GTN does not affect endothelium-dependent vasodilatation but does cause a selective enhancement of alpha 1- but not alpha 2-adrenoceptor-mediated vasoconstriction.

Administration, Cutaneous↗
PubMed2004

This new science of ours: a more or less systematic history of consciousness and transcendence. Part II.

Part I of this paper having postulated the locus of consciousness as residing in a field between primitive mind in participation mystique with the world and a transcendent ground of being, Part II takes up the nature of mind itself in this field in terms of in vivo experiences. Operations and manifestations of consciousness are inexhaustively explored in four venues: 1) Jung's life experiences, 2) Joseph Henderson's theory of psychic development, 3) Eric Voegelin's theory of consciousness and 4) the experiences of analytic patients in far reaches of very long analyses.

Consciousness↗
PubMed2006

Affect consciousness or mentalization? A comparison of two concepts with regard to affect development and affect regulation.

Affect consciousness refers to the ability to adequately perceive, reflect upon and express affect. The concept is used in clinical work with adults, but lacks an equivalent for children's experience of affect. This paper examines the developmental prerequisites for affect consciousness, as well as the concept's applicability to work with children. The main focus is on the development of affect regulation throughout the first 6 years of life. Special emphasis is put on the role of attachment and the unfolding of mentalization ability in this development. The role of play as an organizing factor for affective experience is discussed. Observation of play is highlighted as a strong indicator of affect consciousness in children.

Affect↗
PubMed1997

Autonomic patterns during respiratory suspensions: possible markers of Transcendental Consciousness.

In two experiments, we investigated physiological correlates of transcendental consciousness during Transcendental Meditation sessions. In the first, experimenter-initiated bells, based on observed physiological patterns, marked three phases during a Transcendental Meditation session in 16 individuals. Interrater reliability between participant and experimenter classification of experiences at each bell was quite good. During phases including transcendental consciousness experiences, skin conductance responses and heart rate deceleration occurred at the onset of respiratory suspensions or reductions in breath volume. In the second experiment, this autonomic pattern was compared with that during forced breath holding. Phasic autonomic activity was significantly higher at respiratory suspension onset than at breath holding onset. These easily measured markers could help focus research on the existence and characteristics of transcendental consciousness.

Adult↗
PubMed1968

Procaine perfused into cerebral ventricles and subarachnoid space in conscious and anaesthetized dogs.

1. Perfusion of 1% procaine into the cerebral ventricles of conscious dogs produced mild paresis, defaecation, vomiting, jerky movements of eyelids, brisk nystagmus, increase in amplitude of respiration and sometimes loss of consciousness. Procaine 2% produced paralysis, loss of consciousness and sometimes respiratory depression.2. Procaine 2% perfused into the cerebral ventricles of dogs under chloralose anaesthesia produced an initial increase in amplitude of respiration, which preceded its final depression, which is due primarily to procaine and only partly to a change in pH.3. The site of action for the initial increase in amplitude of respiration was in the fourth ventricle, for it did not occur on perfusion of procaine into the cranial subarachnoid space.4. Perfusion of spinal subarachnoid space with procaine is enough to cause respiratory failure even when the procaine does not reach the medulla.

Anesthesia↗
PubMed1995

Renal effects of infusion of rilmenidine and guanabenz in conscious dogs: contribution of peripheral and central nervous system alpha 2-adrenoceptors.

1. We tested the renal effects of the alpha 2-adrenoceptor agonists, rilmenidine and guanabenz and the antagonists, 2-methoxyidazoxan and idazoxan, in conscious dogs. Our aim was to test the hypothesis that putative imidazoline (I) receptors influence renal function. We reasoned that since rilmenidine and guanabenz are selective for I1- and I2-binding sites respectively, an influence of one of these receptive sites on renal function would be reflected in qualitative differences between the effects of these agents. Moreover, effects mediated by putative I-receptors should be relatively resistant to antagonism by the selective alpha 2-adrenoceptor antagonist, 2-methoxyidazoxan. Since the effects of these drugs on renal function could be mediated in the central nervous system or periphery, the dogs were studied under both normal and ganglion-blocked conditions. 2. In dogs with intact autonomic reflexes, 2-methoxyidazoxan (15 micrograms kg-1 plus 0.6 micrograms kg-1 min-1) produced effects consistent with a generalized increase in sympathetic drive, including increases in mean arterial pressure and plasma renin activity, and a reduction in sodium excretion. In ganglion-blocked dogs, 2-methoxyidazoxan reduced sodium excretion but had no discernible effect on systemic or renal haemodynamics. We conclude that an alpha 2-adrenoceptor-mediated mechanism in the central nervous system tonically inhibits sympathetic drive in the conscious dog. 3. In ganglion-blocked dogs idazoxan (3-300 micrograms kg-1) dose-dependently increased arterial pressure. This was not abolished by concomitant administration of 2-methoxyidazoxan (0.3-30 micrograms kg-1). The pressor effect of idazoxan is therefore probably mediated by an agonist action at alpha 1-adrenoceptors. 4. The effects of infusions of rilmenidine (0.1-1.0 mg kg-1) and guanabenz (10-100 micrograms kg-1) were indistinguishable. They comprised dose-dependent increases in mean arterial pressure, urine excretion, and glomerular filtration rate (the latter in ganglion blocked dogs only), and dose-dependent reductions in heart rate, renal blood flow and sodium excretion (only in dogs with intact autonomic reflexes). All of these effects were antagonized by 2-methoxyidazoxan. 5. We conclude that the renal effects of rilmenidine and guanabenz infusions in conscious dogs are predominantly, if not completely, attributable to activation of alpha 2-adrenoceptors. Our results do not support the hypothesis that putative I-receptors contribute towards the renal effects of these agents.

Adrenergic alpha-Agonists↗
PubMed2003

Can the bispectral index monitor quantify altered level of consciousness in emergency department patients?

OBJECTIVES: A daily part of emergency medicine practice includes assessing patients with altered levels of consciousness (ALOC). The authors hypothesized that a bispectral index monitor (BIS), a processed electroencephalographic monitor traditionally used to monitor patients under anesthesia, would represent an objective quantification of impairment of consciousness. They compared the BIS score with the Glasgow Coma Scale score (GCS) in emergency department (ED) patients with ALOC. METHODS: The authors performed a convenience sampling of ED adults presenting with ALOC (GCS <or= 14). Patients with abnormal baseline mental status were excluded, as were those who were unable to tolerate the forehead BIS leads. The blinded BIS value was recorded after the treating physician assigned a GCS to the patient. The BIS and GCS measurements were then correlated. RESULTS: Data were obtained for 38 patients (20 male, 18 female). The median age was 42 years (range 14 to 93 years). Despite being statistically significant (p = 0.0165), the correlation between the GCS and the BIS score was only moderate (Spearman's rho = 0.387) and displayed wide variability. For example, when the GCS was between 3 and 5, the corresponding BIS scores ranged from 47 to 98. When the GCS was between 12 and 14, the corresponding BIS scores ranged from 56 to 98. Receiver operating characteristic curves for BIS at each GCS threshold demonstrated low discriminatory power (areas under the curve range 0.61 to 0.73). CONCLUSIONS: BIS monitoring does not reliably correlate with GCS in ED patients with ALOC, and does not appear to have potential to accurately quantify impairment of consciousness in this setting.

Adolescent↗
PubMed1977

Lateral specialization and psychiatric issues: speculations on development and the evolution of consciousness.

At the start of this lecture, I invited you to indulge with me in a "dessert" of speculations. I hope it has been a sufficiency, not a surfeit. In summary, we have examined a hypothetical model of some dissociations of consciousness and the expression of unconscious symptoms in adults; we then explored some possible conditions that would account for the development of separate mental streams. In the course of this exploration we were led to question some basic assumptions about the unity of the self, and we proposed some possible mechanisms by which lateral specialization develops in children. This model of the development of lateral specialization has some implications for the study of evolution of the human brain and consciousness. It would seem useful to examine the relationship between the evolution of the commissural systems and the evolution of different capacities for consciousness. According to this model, the full development of lateral specialization depends upon the later myelination of the commissures, which makes possible the autonomy and competition between hemispheres. By this means, only minimal differences between hemispheres need to be specified genetically, since the rest of lateralization can be produced by progressive differentiation, through interactions with the environment. Thus man's eternal, internal struggle may be the price paid for the evolution of lateral specialization.

Adult↗