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At least 937 records · Page 52Linked to original sources
PubMed1988

Growth hormone (GH) secretion in the conscious rat: negative feedback of GH on its own release.

The negative-feedback effects of GH on its own secretion were studied in conscious male and female rats bearing indwelling double-bore venous cannulae. Intravenous infusions of human GH (hGH; 20-60 micrograms/h) or somatostatin (SS; 10 micrograms/h) were given while frequent serial microsamples of blood were withdrawn using an automatic blood-sampling system. In both sexes, i.v. infusions of hGH for 6 h inhibited endogenous GH secretory pulses, with a slow onset of the inhibition. There was no rebound GH secretion immediately following the removal of the hGH infusion, but spontaneous GH secretion gradually returned to normal. Infusions of hGH did not inhibit the pituitary GH response to repeated GH-releasing factor (GRF) injections (1 microgram) given i.v. every 40 min to female rats. By contrast, infusions of SS, which also blocked spontaneous GH release, dramatically reduced the GH responses to serial GRF injections. When SS Infusions were stopped, the subsequent GRF-induced GH secretory responses were enhanced. These results show that GH can inhibit its own release when given by i.v. infusion to conscious male and female rats. Since GH responses to GRF are maintained during a GH infusion, the feedback effect of GH is unlikely to be exerted directly on the pituitary or by increasing SS release. Our results are consistent with the idea that GH feedback in the conscious rat involves an inhibition of GRF release.

Animals↗
PubMedDate not supplied

A measure of neurobehavioral functioning after coma. Part I: Theory, reliability, and validity of Disorders of Consciousness Scale.

This is longitudinal validation study describes the psychometric properties of the Disorders of Consciousness Scale (DOCS). This is Part I of a two-part series. Part II illustrates and describes the clinical and scientific implementation of the DOCS measure. The study was conducted at one intensive care unit, two acute rehabilitation hospitals, and one long-term acute chronic care hospital. Participants were unconscious after severe brain injury (BI). We conducted interrater reliability analyses using ratings from interdisciplinary pairs. Results indicated a higher-than-expected level of agreement and no significant difference between any pairs ( chi-square = 8(5df), p = 0.15) (df = degrees of freedom). Examinations of ratings by discipline groups indicated that the DOCS is impacted minimally by discipline. Validity analyses demonstrate that 23 of 34 test stimuli remain stable over time with no floor or ceiling effect. DOCS measures obtained within 94 days of injury predicted recovery of consciousness up to 1 year after injury (c-indices of 0.70 and 0.86). Positive (0.71) and negative (0.68) predictive values indicate that the DOCS predicts recovery and lack of recovery. Twenty-three of the DOCS test stimuli produce a reliable, valid, and stable measure of neurobehavioral recovery after severe BI that predicts recovery and lack of recovery of consciousness 1 year after injury.

Adult↗
PubMed1999

[Hyperosmolality in central nervous system lupus as a possible complication that results in prolonged consciousness disturbance].

We describe a patient with systemic lupus erythematosus (SLE) with lupus psychosis, who showed prolonged consciousness disturbance due to hyperosmolality. A 51-year-old Japanese woman with SLE was admitted to our hospital for the evaluation and treatment of consciousness disturbance on March 5, 1994. She had not been given prednisolone since 1984, and had been depressive since January 1994. She was diagnosed as active SLE with lupus psychosis due to the presence of thrombocytopenia, proteinuria, positive anti-nuclear antibody (x10,240) as well as the elevation of cerebrospinal fluid (CSF) IL-6 level. A treatment with methylprednisolone (mPL) 100 mg/day was started along with 2 courses of steroid pulse therapy (mPL 1 g/day for 3 consecutive days). She recovered partially from the central nervous system manifestations with a decrease in CSF IL-6 level 2 weeks after this treatment. However, her consciousness level was exacerbated again thereafter. Blood examination disclosed the elevation of plasma osmolality (319 mOsm/kg) with poor responses of plasma antidiuretic hormone (4.6 pg/ml). She died from systemic aspergillosis on April 26, 1994. Pathological examination on autopsy showed no abnormality in hypothalamus and pituitary gland. It is suggested that this patient was complicated with lupus psychosis as well as hyporesponsiveness of osmoreceptor. Rheumatologists should be aware of this complication in patients with CNS lupus as a possible cause for intractable CNS manifestations.

Biomarkers↗
PubMed2006

Mammalian and avian neuroanatomy and the question of consciousness in birds.

Some birds display behavior reminiscent of the sophisticated cognition and higher levels of consciousness usually associated with mammals, including the ability to fashion tools and to learn vocal sequences. It is thus important to ask what neuroanatomical attributes these taxonomic classes have in common and whether there are nevertheless significant differences. While the underlying brain structures of birds and mammals are remarkably similar in many respects, including high brain-body ratios and many aspects of brain circuitry, the architectural arrangements of neurons, particularly in the pallium, show marked dissimilarity. The neural substrate for complex cognitive functions that are associated with higher-level consciousness in mammals and birds alike may thus be based on patterns of circuitry rather than on local architectural constraints. In contrast, the corresponding circuits in reptiles are substantially less elaborated, with some components actually lacking, and in amphibian brains, the major thalamopallial circuits involving sensory relay nuclei are conspicuously absent. On the basis of these criteria, the potential for higher-level consciousness in these taxa appears to be lower than in birds and mammals.

Animals↗
PubMed1992

Changes in body consciousness relate to regularity of exercise training.

Previous work has indicated improvement for scores on self-reported measures of body consciousness as aerobic fitness increased. To test whether exercise sufficient to improve aerobic fitness must be sustained on a regular basis to achieve positive changes in body consciousness, two separate periods of exercise training of 2 or 3 weeks duration were completed by nine female volunteers. The two exercise sessions were separated by 10 days of no exercise. Five women, as controls, did not exercise. Despite significant physiological improvement in the exercisers, no changes in self-perceived body self-consciousness were observed. Such changes may depend on the maintenance of a regular exercise regimen or the magnitude of physiological improvement.

Adult↗
PubMed1995

Human EEG responses to classical music and simulated white noise: effects of a musical loudness component on consciousness.

The main purpose of the present study was to investigate the psychophysiological effects of music on human EEG. For this purpose, a sound modulator was developed which simulates the sound-pressure variations of a given piece of music by white noise (sim-music). Using this apparatus, the author tested the psychophysiological effects of music on human EEG. The electroencephalograms (EEG), electrocardiograms (ECG), and electrooculograms (EOG) of eight normal volunteers were recorded for a total of 21 min., 5 sec. per session for each subject under three sound conditions: silence for 5 min., two types of music (music) or two types of simulated noise (sim-music) for 11 min., 5 sec., followed by silence for another 5 min. Each subject was exposed to a total of 10 music and 10 sim-music conditions. At the low consciousness level (drowsiness, Stage S1), higher delta component power densities were observed with sim-music than with music. Thus, even in the same Stage S1, entire physiological consciousness levels may be higher when listening to music than to sim-music. While listening to music, many subjects reported that they felt pleasantly relaxed or comfortable. However, with the sim-music, they reported feeling unpleasantly weary and sleepy. It seems that the mental set toward two sound conditions differed greatly for many subjects. In Stage S1, the differences in EEG slow components showed that the differences in consciousness had a physiological aspect and indicated differences in mental set toward both sound conditions and mental activity during the listening conditions.

Adult↗
PubMed1981

Informational analysis of consciousness.

Informational analysis of neurophysiological processes leads to the conclusion that the unconscious and subconscious comprise especially algorithmic processes, which take place according to precise rules, and awareness and consciousness comprise especially heuristic processes, for which the nervous system does not provide precise rules. The part played by awareness and consciousness is to find the processing rules of information which cannot be algorithmically processed. This paper describes the way that awareness and consciousness manage to discover the processing rules of information and the manner of their contribution to the adaptation of the unconscious and of the subconscious to the very variable conditions of the environment.

Awareness↗
PubMed1988

Morphine-induced modification of the functional properties of ventral tegmental area neurons in conscious rat.

To elucidate the functional role of mesolimbocortical dopamine(DA)-containing and other mediator-specific neurons in mediation of different pharmacological effects of opiates, morphine (6 mg/kg, SC)-induced modification of spontaneous discharges of different types VTA-units and their changes during polymodal activating and aversive stimulation and spontaneous movement were studied in conscious, restrained rats. In presumed DA-containing neurons (D-type) prolonged increase of discharge rate, regularization of their pattern and decrease of firing changes during all types of external stimulation and spontaneous or stimulus-induced movement activity were found. This decrease of unit firing changes was connected with significant rising of atypical, compared with control conditions, firing inhibitions. Changes of presumed acetylcholine(ACh)-containing neurons (A-B type) properties were defined as prolonged and pronounced decrease of firing rate, intensification of bursting pattern and decrease of discharge changes during all types of stimulation used and animal movements. This decrease of discharge changes was associated with significant lowering of activations-typical for these units in control conscious animals and rising of firing inhibitions. In presumed ACh- or GABA-containing interneurons of C-type a significant decrease of firing rate, increase of activations and decrease of firing inhibitions, typical for these units in control conscious rats were found. The modifications of different VTA-unit functional properties are discussed in view of main pharmacological effects of opiates (sedation, analgesia, positive reinforcement, movement activation).

Acoustic Stimulation↗
PubMed1989

Field model of consciousness: EEG coherence changes as indicators of field effects.

Changes in EEG coherence patterns were used to test a field model that posits a common field of "pure consciousness" linking all individuals. In ten trials, EEG was concurrently measured from pairs of subjects, one practicing Transcendental Meditation (TM) and the TM-Sidhi technique of "Yogic Flying" (YFg)--said to enliven the proposed field of consciousness--and the other performing a computer task. Box-Jenkins ARIMA transfer function analysis indicated that coherence changes in the YF's 5.7-8.5 Hz band, the band sensitive to TM and YFg, consistently led coherence changes in the other subject's 4.7-42.7 Hz band. A clear relationship was seen among subjective reports, coherence patterns, and strength of intervention effects. These data support a field model of consciousness. Alternate explanations are explored.

Adult↗
PubMed2003

[Outline for the theory of diagnosis and treatment based on the correlation between consciousness and organ].

Enlightened by the idea of correlation of mind and body in traditional Chinese medicine and western medicine, integrating his long-term clinical experience, the author brings forward a concise and practical theory for diagnosis and treatment based on the correlation between consciousness and organ in this article. This article includes:(1)introducing the conceptions of consciousness and organ;(2) pointing out the diagnostic and remedial meaning of the four kinds of condition about the correlation of sense and organ;(3) pointing out the diagnostic and remedial meaning of the five kinds of condition about the correlation of desire and organ;(4) how to select herbal and mineral drug to treat the disorders of consciousness and organ;(5) citing some examples to prove the diagnostic and remedial effect of the theory on intractable diseases.

Brain↗
PubMed2003

The effect of midazolam on conscious, controlled processing: evidence from the process-dissociation procedure.

The benzodiazepine midazolam produces a dense anterograde amnesia. Recent findings (see, e.g., Hirshman, Passannante, & Arndt, 2001) have demonstrated that midazolam produces larger impairments on explicit memory tests such as free recall and recognition memory than on implicit memory tests such as perceptual identification and free association. Such findings suggest that midazolam impairs conscious, controlled memory processes. In the present experiments, we used Jacoby's (1991, 1998) process-dissociation procedure to examine this hypothesis. Our results demonstrate that midazolam increases the production of old items on the exclusion task and reduces the production of old items on the inclusion task. Moreover, generation effects, hypothesized to arise from conscious processes, are reduced by midazolam on both tasks. Analyses using both independence and redundancy models of the process-dissociation procedure confirm the conclusion that midazolam impairs conscious memory processes.

Consciousness↗
PubMed1999

Analyzing estimates of automatic and conscious retrieval in between- and within-subjects designs.

The process dissociation procedure (PDP) was developed as a means of quantifying the contributions of conscious and automatic retrieval to memory performance. Although the required inclusion and exclusion conditions are manipulated within subjects in most experiments, several researchers have expressed concerns that the instructions may be particularly difficult to follow under these conditions. Thus, manipulating instructions between subjects may have some advantages, although some aspects of the statistical analysis of conscious and automatic estimates are not routine in such a design. We describe a procedure for this analysis and present some initial data to illustrate its application to PDP. We also comment on other issues related to the calculation of estimates of automatic and conscious retrieval in between- and within-subjects designs.

Consciousness↗
PubMed1999

Increased synchronization of neuromagnetic responses during conscious perception.

In binocular rivalry, the observer views two incongruent images, one through each eye, but is conscious of only one image at a time. The image that is perceptually dominant alternates every few seconds. We used this phenomenon to investigate neural correlates of conscious perception. We presented a red vertical grating to one eye and a blue horizontal grating to the other eye, with each grating continuously flickering at a distinct frequency (the frequency tag for that stimulus). Steady-state magnetic fields were recorded with a 148 sensor whole-head magnetometer while the subjects reported which grating was perceived. The power of the steady-state magnetic field at the frequency associated with a grating typically increased at multiple sensors when the grating was perceived. Changes in power related to perceptual dominance, presumably reflecting local neural synchronization, reached statistical significance at several sensors, including some positioned over occipital, temporal, and frontal cortices. To identify changes in synchronization between distinct brain areas that were related to perceptual dominance, we analyzed coherence between pairs of widely separated sensors. The results showed that when the stimulus was perceived there was a marked increase in both interhemispheric and intrahemispheric coherence at the stimulus frequency. This study demonstrates a direct correlation between the conscious perception of a visual stimulus and the synchronous activity of large populations of neocortical neurons as reflected by stimulus-evoked steady-state neuromagnetic fields.

Adult↗
PubMed2000

Conscious and unconscious processing of nonverbal predictability in Wernicke's area.

The association of nonverbal predictability and brain activation was examined using functional magnetic resonance imaging in humans. Participants regarded four squares displayed horizontally across a screen and counted the incidence of a particular color. A repeating spatial sequence with varying levels of predictability was embedded within a random color presentation. Both Wernicke's area and its right homolog displayed a negative correlation with temporal predictability, and this effect was independent of individuals' conscious awareness of the sequence. When individuals were made aware of the underlying sequential predictability, a widespread network of cortical regions displayed activity that correlated with the predictability. Conscious processing of predictability resulted in a positive correlation to activity in right prefrontal cortex but a negative correlation in posterior parietal cortex. These results suggest that conscious processing of predictability invokes a large-scale cortical network, but independently of awareness, Wernicke's area processes predictive events in time and may not be exclusively associated with language.

Adult↗
PubMed2000

Development of a special catheterbag to enable artificial organ evaluation in conscious, unrestrained pigs: technical note.

Pigs are widely used as models for a variety of human diseases, because many of their physiological functions closely resemble those of humans. However, information on instrumentation techniques is still scarce. In particular, experiments in conscious pigs focused on extracorporeal circuits are connected to a variety of methodical problems with respect to the handling of the animals. Usually, pigs are placed in restraint-slings during the application of an extracorporeal system. However, this method of restraint may lead to excessive mental distress even in trained animals. The latter might influence the results and certainly affects principles of animal welfare. Our own experiences with instrumented, conscious, but unrestrained dogs encouraged us to modify methods used for the fixation of in-dwelling central venous catheters in dogs with special regard to the species specific behaviour and phenotype of pigs. A cord retractable leash (CRL) was used for maintaining a safe distance between the animal and the outer ends of the catheters. To prevent dehiscences of the required fixation sutures a new catheter bag (CB) was designed to counteract tension forces caused by the CRL's spring-mechanism. The combination of both the CRL and CB enabled us to conduct safe experiments with conscious, unrestrained pigs. We alleviated the mental distress these animals were exposed to in comparison to former methods based on restraint of the animals.

Animals↗
PubMed2001

Cajal and consciousness. Introduction.

One hundred years after Santiago Ramón Cajal established the bases of modern neuroscience in his masterpiece Textura del sistema nervioso del hombre y de los vertebrados, the question is stated again: What is the status of consciousness today? The responses in this book, by contemporary leading figures of neuroscience, evolution, molecular biology, computer science, and quantum physics, collectively compose a fascinating conceptual landscape. Both the evolutionary emergence of consciousness and its development towards the highest level may be analyzed by a wealth of new theories and hypotheses, including Cajal's prescient ones. Some noticeable gaps remain, however. Celebrating the centennial of Textura is a timely occasion to reassess how close--and how far--our system of the sciences is to explaining consciousness.

Animals↗
PubMed1975

Consciousness from neurons.

Consciousness derives from a neural process that requires unceasing metabolic support, and probably involves only a select population of neocortical elements. The essential process must operate for roughly more than 100 ms for sensorial registration (Libet). It is highly unlikely that the essence of the process lies in its computational logic and hence it can never be produced by inanimate machines. Since the process is thus unique to neurons, and since the consciousness of the left hemisphere normally communicates with that of the right (and probably vice versa) via the forebrain cornmissures, at least some portion of the nerve impulse traffic across the commissures must possess a wholly mysterious property enabling its transcendent compilation into a unified conscious experience. Comprehending the nature of this property which couples ionic fluxions into mentality is the quintessential problem of science. The forebrain commissures may ultimately provide the clues for its solution.

Animals↗
PubMed2002

[ Physiology of consciousness. II].

At present, no plausible theory or even working hypothesis of the formation of human consciousness based on physiological processes of the central nervous system has been proposed. An obvious and principal obstacle is, how an immaterial process, consciousness, may arise from any material processes, and vice versa. For this reason, it is extremely difficult to propose such a hypothesis. Therefore, a working hypothesis is proposed based on well known interactions of the human consciousness with quantum submicroscopic processes.

Central Nervous System↗