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PubMed2003

Regaining consciousness for prolonged comatose patients with right median nerve stimulation.

During the past half year, we have utilized right median nerve stimulation (produced by Empi. Co. USA) to awaken consciousness of patients on 6 cases, 2 with brain trauma, one with aneurysm rupture, one with hemorrhagic stroke and two with hypoxic encephalopathy. The comatose duration ranged from 6 to 17 weeks. All patients underwent SPECT scan for cerebral perfusion evaluation and neurotransmitter quantification before and after the stimulation. The stimulation time lasted from 8 to 10 hours on daytime. The stimulation persisted for 3 months in all patients. Four patients recovered from the consciousness within 35 days. There was no obvious clinical improvement in two patients. Brain perfusion increased in all cases through the SPECT study after stimulation. The elevation of neurotransmitter in CSF was found in 5 out of the 6 cases. Median nerve stimulation elevates the cerebral blood flow and may influence the patient's consciousness. Young patients (<40 years old) had better results than old patients. The stimulation could be initiated if the patient's acute stage was over. In our series, although increase in cerebral blood flow was found in all cases, some patients did not regain consciousness.

Adolescent↗
PubMed1990

Cardiovascular effects of flesinoxan in anaesthetized and conscious dogs.

Stimulation of 5-HT1A receptors is known to decrease the arterial blood pressure in anaesthetized rats, cats and dogs. We investigated the hypotensive activity of flesinoxan (0.1 + 0.2 + 0.7 mumol/kg), a 5-HT1A-receptor agonist, in dogs anaesthetized with either morphine and pentobarbital or enflurane and also in the conscious state. Flesinoxan led to a decrease in arterial blood pressure in anaesthetized, but not in conscious dogs. In the conscious state the marked increase in heart rate, which can be taken as an indicator of sympathetic tone, may have masked the consequences of vasodilatation. These different haemodynamic responses to flesinoxan may be dependent on side effects of the drug in the conscious dogs, in particular hyperventilation and salivation combined with anxiety, and on the magnitude of the decrease in baroreceptor reflex activity during anaesthesia with morphine and pentobarbital on the one hand and enflurane on the other hand.

Anesthesia↗
PubMed2006

Inter-individual variability of the facial morphology during conscious smiling.

INTRODUCTION: Since many simulation and animation procedures for mimicry are based on averaged values and do not take into account an individual's situation, the goal of this study was to investigate the intra- and inter-individual variability of conscious smiling. MATERIALS AND METHODS: Twenty-three surface points were marked on the faces of 31 adult test individuals. Six photographs of each subject's face were then taken under standardized conditions, one with a neutral facial expression and five while the individual was asked to smile (conscious smile "on command"). After digital superposition of the individual images (neutral and smiling) the displacements were measured for every measurement point on each individual. All data underwent statistical evaluation after normalization in the vertical and horizontal directions. Evaluation of intra- and inter-individual variability was carried out by analyzing the corresponding coefficients of variation and the formation of confidence intervals (confidence level 95%). RESULTS: The repeated measurements upon conscious smiling showed a moderate intra-individual variability with coefficients of variation under 10%. In contrast, the inter-individual variability of the measured values was relatively high. Here variation coefficients were measured of between 28% and 60% depending on the localization of the measuring point. The displacements' absolute magnitude was greatest in the lower facial third. The two corners of the mouth, the upper lip in the philtrum area, the cheeks and the side wings of the nose revealed the highest displacements. CONCLUSION: Due to the high inter-individual variability, an analysis based on averaged values or a simulation of the conscious smile must be viewed with a certain amount of criticism.

Adult↗
PubMed1998

Cerebral blood flow measurement in patients with impaired consciousness: usefulness of 99mTc-HMPAO single-photon emission tomography in clinical practice.

The relationship between impairment of consciousness and quantitative cerebral blood flow (CBF) was investigated. The mean CBF of the whole brain was measured by the Patlak-plot method using technetium-99m hexamethylpropylene amine oxime single-photon emission tomography (99mTc-HMPAO SPET) in patients with the following diseases: cerebral infarction, intraparenchymal haemorrhage, subarachnoid haemorrhage, brain tumour and cerebral contusion. The clinical symptoms were evaluated according to the severity of impaired consciousness, aphasia and dementia. Four hundred and eighty-five CBF measurements were performed. Patients with alert consciousness showed an age-related decline in mean CBF. Patients with aphasia showed a significant reduction in mean CBF compared with those without aphasia. Impaired consciousness was proportional to reduction in mean CBF regardless of types of pathology, and the size of lesion did not influence the mean CBF. Patients with dementia showed a significant reduction in mean CBF proportional to the severity of dementia. The quantitative measurement of CBF using 99mTc-HMPAO SPET is reliable in clinical evaluations.

Adolescent↗
PubMed2004

Animal expertise, conscious or not.

Rossano (Cognition 89:207, 2003) proposes expertise as an indicator of consciousness in humans and other animals. Since there is strong evidence that the development of expertise requires deliberate practice (Ericsson in The road to excellence: the acquisition of expert performance in the arts and sciences, sports and games 1996), and deliberate practice appears to be outside of the bounds of unconscious processing, then any signs of expertise development in an animal are indicators of consciousness. Rossano's argument may lead to an unsolvable debate about animal consciousness while causing researchers to overlook the underlying reality of animal expertise. This article provides evidence indicative of animals meeting each of the three definitions of expertise established in the scientific literature: expertise as a social construction, expertise as exceptional performance, and expertise as knowledge. In addition, cases of deliberate practice by non-human animals are offered. Acknowledging some animals as experts, regardless of consciousness, is warranted by the research findings and would prove useful in solving many issues remaining in the human expertise literature.

Animals↗
PubMed1987

Time course of recovery of "stunned" myocardium following variable periods of ischemia in conscious and anesthetized dogs.

Persistence of regional contractile dysfunction after restoration of blood flow to transiently ischemic myocardium has been well described. To date, most studies have been performed in anesthetized animals. The present investigation compared the time course of recovery of regional segment shortening (percentage of segment shortening) in anesthetized versus conscious dogs subjected to a brief period of total occlusion of the left anterior descending coronary artery. Periods of occlusion lasting 5, 10, and 15 minutes were followed by 3 hours of reperfusion. Dogs anesthetized with sodium pentobarbital (30 mg/kg intravenously) had a significantly higher heart rate and blood pressure and lower dP/dt than conscious dogs. Coronary artery occlusion resulted in similar degrees of regional dyskinesis or akinesis, indicative of severe myocardial ischemia, in all experiments. During reperfusion, a gradual return of contractile function toward baseline was observed. At the end of the first 15 minutes of reflow, dogs subjected to 5 minutes of coronary occlusion demonstrated approximately 70% of control segment shortening in the previously ischemic zone. Animals subjected to 10- and 15-minute periods of coronary artery occlusion showed approximately 60% and 40% of control segment shortening at the same time point, respectively. The remainder of the 3-hour reperfusion period was characterized by a more gradual recovery of regional segment function. No differences were observed between anesthetized and conscious animals. It is concluded that the time course of functional recovery of postischemic reperfused myocardium is directly related to the duration of coronary occlusion and is similar in conscious and anesthetized dogs.

Anesthesia, Intravenous↗
PubMed1995

Consciousness and the natural method.

'Consciousness' is a superordinate term for a heterogeneous array of mental state types. The types share the property of 'being experienced' or 'being experiences'--'of there being something that it is like for the subject to be in one of these states.' I propose that we can only build a theory of consciousness by deploying 'the natural method' of coordinating all relevant informational resources at once, especially phenomenology, cognitive science, neuroscience and evolutionary biology. I'll provide two examples of the natural method in action in mental domains where an adaptationist evolutionary account seems plausible: (i) visual awareness and (ii) conscious event memory. Then I will discuss a case, (iii), dreaming, where I think no adaptationist evolutionary account exists. Beyond whatever interest the particular cases have, the examination will show why I think that a theory of mind, and the role conscious mentation plays in it, will need to be built domain-by-domain with no a priori expectation that there will be a unified account of the causal role or evolutionary history of different domains and competences.

Animals↗
PubMed1991

Toward an analysis of conscious activity: 2. The functions of sleep and wakefulness.

What we generally call information is created through interference between regular information and reverse information. In this process, conscious activity is the creator of information. We can assume that the following five-stage mechanism exists inside the brain: 1) a mechanism that creates consciousness and recognizes information; 2) a mechanism that accumulates information in the neural circuits; 3) a mechanism that combines and separates the self-conscious mind and fragments of accumulated information; 4) a mechanism that accesses the operating system or distributes information to localized neural circuits; and 5) a mechanism that allows the operating system to modify itself with an increase in the amount of information. These mechanisms can be considered to belong to the category of conscious activity, which is created by a combination of potentialization of sleep and potentialization of wakefulness.

Brain↗
PubMedDate not supplied

Evidence for a relationship between recovery from anaesthesia, modified state of consciousness and striatal voltammetric levels of ascorbic acid.

The effects of various procedures which modify consciousness were studied on the extracellular concentration of ascorbic acid (AA), 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindolacetic acid (5HIAA) in rat striatum, as measured by differential pulse voltammetry (DPV) with electrically pretreated carbon fibre micro-electrodes (CFE). Recovery from anaesthesia (produced by 500 mg/kg i.p. chloral hydrate) was accompanied by a six-fold increase in extracellular striatal AA levels, while negligible changes in DOPAC and 5HIAA occurred. Following complete recovery from anaesthesia, the animals were re-injected with the same dose of anaesthetic which specifically reduced AA levels by 90% (DOPAC levels were unchanged and 5HIAA concentrations slightly reduced). In conscious rats, the neuroleptic haloperidol (1 mg/kg i.p., n = 5) and the minor tranquillizer diazepam (10 mg/kg i.p., n = 5), both considered as behaviourally depressant drugs, reduced extracellular AA levels to 50% of controls. The psychomotor stimulant D-amphetamine (1 mg/kg i.p., n = 5) increased AA levels by 90% over controls. Stress activation of animals (handling for 10 min, n = 10) also produced a transient, significant increase (180% of control values) in this striatal parameter. Taken together with previous reports, our results suggest a close relationship between the state of consciousness and extracellular AA levels in the rat striatum and that this relationship appears to be more correlated to AA as no such clear interdependence was noted between the levels of consciousness and extracellular striatal DOPAC or 5HIAA.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

The long-latency auditory evoked potential as a measure of the level of consciousness during sufentanil anesthesia.

The long-latency auditory evoked potential was recorded during opioid anesthesia to evaluate its usefulness for assessing the level of consciousness. Eight patients undergoing coronary artery surgery under high-dose sufentanil anesthesia following a lorazepam premedication were tested. Four waves were studied: the N1, P2, P3, and the slow wave (SW). The amplitude of N1 and that of the SW were reduced by sufentanil, but the differences did not reach significance. The amplitude and latency of P2 and the latency of the SW were significantly reduced. The P3, which is possibly a specific indicator for consciousness, was present before induction and absent during anesthesia. There was no conscious recall for intraoperative events. Preservation of the N1, P2, and SW, which are abolished by nonopioid general anesthetics, suggests that auditory processing proceeds further during anesthesia with sufentanil. However, no electrophysiologic evidence of consciousness was found during sufentanil anesthesia.

Adult↗
PubMed2006

Level of consciousness as a conditioning factor of F wave generation in stroke patients.

OBJECTIVE: The current study aimed to investigate whether the level of consciousness influenced the F wave generation, as an independent factor. METHODS: Forty three patients with acute stroke were divided according to their level of consciousness in two groups; to those with Glasgow scale (GCS) score 3-7 indicating coma (group I) and those with GCS score 8-15 (group II). A series of 40 electrical stimuli were delivered to the ulnar nerve bilaterally in order to obtain F waves. The following variables were estimated and then compared between groups: F persistence, F wave latency, amplitude and duration. All studies were performed within 3 days from the onset of the stroke symptoms. RESULTS: The main finding to emerge was the significantly reduced F wave persistence in the group of patients with low GCS score as opposed to patients allocated in the group with GCS score 8-15. This result is referred to F waves obtained from both the affected and unaffected limb. F wave minimum latency was also prolonged in the group with low GCS score, whilst the comparison of all other F wave variables revealed no significant differences between groups I and II. F wave persistence measurements did not differ between the affected and unaffected sides. Stroke location and type (ischemic or hemorrhagic) were not associated with alterations of F wave measurements. CONCLUSIONS: Our results on stroke patients suggest that generation of F waves, expressed by the F wave persistence is associated with the level of consciousness. SIGNIFICANCE: F wave study may be useful as an objective measure in documenting the severity of consciousness impairment.

Action Potentials↗
PubMed2006

Autonomic reactivity to sensory stimulation is related to consciousness level after severe traumatic brain injury.

OBJECTIVE: To examine changes in the activity of the autonomic nervous system (ANS) that are related to recovery to consciousness in the post-acute phase after severe traumatic brain injury (sTBI). METHODS: Skin conductance and heart rate reactivity to sensory stimulation were recorded every 2 weeks for an average period of 3.5 months in 16 adolescent patients, during the assessment of their level of consciousness (LoC), and their cognitive and functional behaviour. RESULTS: Both heart rate variability (HRV) and skin conductance level (SCL) in reaction to sensory stimulation changed with recovery to consciousness. Indices of HRV and SCL that represent sympathetic activity of the autonomic nervous system (ANS) increased with recovery, whereas indices that represent parasympathetic activity decreased. In addition, we observed an increase in sympathovagal balance of the ANS with recovery. CONCLUSIONS: Recovery to consciousness determined by clinical observation in sTBI in the post-acute phase is related to changes in SCL and HRV during sensory stimulation. ANS reactivity to environmental stimulation can therefore give objective supplementary information about the clinical state of sTBI patients, and can contribute to decision-making in the treatment policy of unresponsive patients. SIGNIFICANCE: These findings demonstrate that autonomic reactivity can be informative concerning how a severely damaged nervous system reacts to environmental stimulation and how, in a recovering nervous system, this reactivity changes.

Adolescent↗
PubMed2005

The relationship between object files and conscious perception.

Object files (OFs) are hypothesized mid-level representations which mediate our conscious perception of persisting objects-e.g. telling us 'which went where'. Despite the appeal of the OF framework, not previous research has directly explored whether OFs do indeed correspond to conscious percepts. Here we present at least one case wherein conscious percepts of 'which went where' in dynamic ambiguous displays diverge from the analogous correspondence computed by the OF system. Observers viewed a 'bouncing/streaming' display in which two identical objects moved such that they could have either bounced off or streamed past each other. We measured two dependent variables: (1) an explicit report of perceived bouncing or streaming; and (2) an implicit 'object-specific preview benefit' (OSPB), wherein a 'preview' of information on a specific object speeds the recognition of that information at a later point when it appears again on the same object (compared to when it reappears on a different object), beyond display-wide priming. When the displays were manipulated such that observers had a strong bias to perceive streaming (on over 95% of the trials), there was nevertheless a strong OSPB in the opposite direction-such that the object files appeared to have 'bounced' even though the percept 'streamed'. Given that OSPBs have been taken as a hallmark of the operation of object files, the five experiments reported here suggest that in at least some specialized (and perhaps ecologically invalid) cases, conscious percepts of 'which went where' in dynamic ambiguous displays can diverge from the mapping computed by the object-file system.

Attention↗
PubMed2004

Criteria for an effective theory of consciousness and some preliminary attempts.

In the physical sciences a rigorous theory is a hierarchy of descriptions in which causal relationships between many general types of entity at a phenomenological level can be derived from causal relationships between smaller numbers of simpler entities at more detailed levels. The hierarchy of descriptions resembles the modular hierarchy created in electronic systems in order to be able to modify a complex functionality without excessive side effects. Such a hierarchy would make it possible to establish a rigorous scientific theory of consciousness. The causal relationships implicit in definitions of access consciousness and phenomenal consciousness are made explicit, and the corresponding causal relationships at the more detailed levels of perception, memory, and skill learning described. Extension of these causal relationships to physiological and neural levels is discussed. The general capability of a range of current consciousness models to support a modular hierarchy which could generate these causal relationships is reviewed, and the specific capabilities of two models with good general capabilities are compared in some detail.

Consciousness↗
PubMed2004

Handedness and the fringe of consciousness: strong handers ruminate while mixed handers self-reflect.

Previous research found that mixed handers (i.e., those that are more ambidextrous) were more likely than strong handers to update their beliefs (Niebauer, Aselage, & Schutte, 2002). It was assumed that this was due to greater degrees of communication between the two cerebral hemispheres in mixed handers. Niebauer and Garvey (2004) made connections between this model of updating beliefs and metacognitive processing. The current work proposes that variations in interhemispheric interaction (as measured by degree of handedness) contribute to differences in consciousness, specifically when consciousness is used in rumination versus the metacognitive task of self-reflection. Using the Rumination-Reflection Questionnaire (Trapnell & Campbell, 1999), predictions were supported such that strong handedness was associated with self-rumination; whereas, mixed handedness was associated with increased self-reflection p values<.01, (N=255). James's (1890) concept of the "fringe of consciousness" is used to make connections between metacognition, updating beliefs, and self-reflection. Several studies are reviewed suggesting that mixed handers experience fringe consciousness to a greater degree than strong handers.

Adult↗
PubMed2005

Criteria for consciousness in humans and other mammals.

The standard behavioral index for human consciousness is the ability to report events with accuracy. While this method is routinely used for scientific and medical applications in humans, it is not easy to generalize to other species. Brain evidence may lend itself more easily to comparative testing. Human consciousness involves widespread, relatively fast low-amplitude interactions in the thalamocortical core of the brain, driven by current tasks and conditions. These features have also been found in other mammals, which suggests that consciousness is a major biological adaptation in mammals. We suggest more than a dozen additional properties of human consciousness that may be used to test comparative predictions. Such homologies are necessarily more remote in non-mammals, which do not share the thalamocortical complex. However, as we learn more we may be able to make "deeper" predictions that apply to some birds, reptiles, large-brained invertebrates, and perhaps other species.

Adaptation, Physiological↗
PubMed2005

Fringe consciousness in sequence learning: the influence of individual differences.

We first describe how the concept of "fringe consciousness" () can characterise gradations of consciousness between the extremes of implicit and explicit learning. We then show that the NEO-PI-R personality measure of openness to feelings, chosen to reflect the ability to introspect on fringe feelings, influences both learning and awareness in the serial reaction time (SRT) task under conditions that have previously been associated with implicit learning (). This provides empirical evidence for the proposed phenomenology and functional role of fringe consciousness in so-called implicit learning paradigms (). Introducing an individual difference variable also helped to identify possible limitations of the exclusion task as a measure of conscious sequence knowledge. Further exploration of individual differences in fringe awareness may help to avoid polarity in the implicit learning debate, and to resolve apparent inconsistencies between previous SRT studies.

Adolescent↗
PubMed2005

Aspects of the unity of consciousness and everyday memory failures.

We argue that analyzing everyday memory failures in terms of the "unity of consciousness" can elucidate the bases of such failures. A perfect unity amongst one's mental states is rare. In extreme cases the unity of consciousness can breakdown in dramatic fashion (e.g., in Dissociative Identity Disorder), but such breakdowns also occur in less dramatic ways that affect us in everyday life. For example, disruptions in the unity of consciousness can result in everyday memory failures, such as forgetting to put on a tie for an important formal meeting. After providing some philosophical background into the notions of "unity of consciousness" and "functionalism," we offer preliminary analyses of three examples of everyday memory failure. We then introduce and develop what we call the "unity model" of memory failure and show how it explains the examples. We also describe different ways that unity can break down which, in turn, can lead to memory failure and inappropriate behavior. We then show how slips of action and other kinds of cognitive failures (e.g., memory blocks) differ from everyday memory failures. Finally, we examine alternative models (e.g., Absentmindedness and Multimodal) arguing that the unity model is preferable, and then show how our model is consistent with some experimental results.

Cognition↗