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PubMed2002

Neural correlates of conscious and unconscious vision in parietal extinction.

Brain areas activated by stimuli in the left visual field of a right parietal patient suffering from left visual extinction were identified using event-related functional magnetic resonance imaging. Left visual field stimuli that were extinguished from awareness still activated the ventral visual cortex, including areas in the damaged right hemisphere. An extinguished face stimulus on the left produced robust category-specific activation of the right fusiform face area. On trials where the left visual stimulus was consciously seen rather than extinguished, greater activity was found in the ventral visual cortex of the damaged hemisphere, and also in frontal and parietal areas of the intact hemisphere. These findings extend recent observations on visual extinction, suggesting distinct neural correlates for conscious and unconscious perception.

Aged↗
PubMed2002

Sleep cycle in patients in a state of permanent unconsciousness.

Since the recent diagnostic criteria for persistent vegetative state (PVS) require the presence of a sleep-wake cycle, certain patients in similar conditions should be excluded from PVS. Since the diagnosis of PVS might correlate with legal issues, an accurate definition is necessary. To clarify the clinical significance of a sleep-wake cycle, 12 patients in a state of permanent unconsciousness after brain damage were clinically and electrophysiologically reviewed. In addition to routine EEG, evoked potentials and MRI, the simultaneous recordings of EEG and patients by videotape were performed for 24 hours. Four patients who showed severe brain stem damage did not show a sleep-wake cycle. In the other eight patients, a sleep-wake cycle was observed. However, among these patients there was no obvious difference in their clinical status. Although these data suggest that the presence of a sleep-wake cycle might reflect the brain stem damage, it is considered that the presence of a sleep-wake cycle might be unnecessary for the diagnostic criteria for PVS. Further study of various forms of brain damage will provide better understanding of the significance of the presence of a sleep-wake cycle.

Adolescent↗
PubMed2006

Unconscious vision: new insights into the neuronal correlate of blindsight using diffusion tractography.

The existence of several types of unconscious vision, or 'blindsight', has convincingly been demonstrated in numerous studies, and their neuronal correlates have been hypothesized according to the nature of the residual vision observed. We used diffusion tensor imaging (DTI) tractography to demonstrate an association between the presence of 'Type I'- blindsight or 'attention blindsight' and reconstructed superior colliculi (SC) fibre tracts in hemispherectomized subjects, in support of the hypothesis that this subcortical structure plays a pivotal role in this type of blindsight. Before the DTI study, 'Type I' blindsight was identified in two of four hemispherectomized subjects by using a spatial summation effect paradigm, an indirect behavioural method, in which subjects were unaware of a stimulus presented in their blind visual field and were required to respond to an identical stimulus presented simultaneously in their intact field. SC tracts were then reconstructed in six control subjects, the two hemispherectomized subjects with blindsight and the two hemispherectomized subjects without blindsight. Whereas control subjects demonstrated mainly ipsilateral connections to visual association areas, parietal cortex, prefrontal areas and to an area close to the frontal eye fields, hemispherectomized subjects with blindsight showed ipsi- and contralateral connections from the SC to visual association areas, primary visual areas, parietal areas, prefrontal areas and to the posterior part of the internal capsule. In contrast, no projections from the SC on the hemispherectomized side were observed in hemispherectomized subjects without blindsight, in support of a key role of this structure in 'Type-I' or 'attention blindsight'.

Adult↗
PubMed1991

Evaluation of factors influencing myocardial infarct size in unconscious dogs.

STUDY OBJECTIVE: The aim was to evaluate the factors determining myocardial infarct size in unconscious dogs. DESIGN: In anaesthetised open chest dogs, the left anterior descending coronary artery was occluded either by ligation or by thrombosis for different time periods (1.5 h, 4 h, 24 h), with or without reperfusion. Haemodynamic variables were recorded throughout the experiment. Radioactive microspheres (15 microns) were injected at the end of the ischaemic period to measure regional myocardial blood flow. Infarct size and area at risk were determined by the Evans blue triphenyltetrazolium staining technique followed by planimetry. SUBJECTS: Mongrel dogs of either sex (n = 16-42 per experiment), weight 18-25 kg, were used. MEASUREMENTS AND MAIN RESULTS: A large interindividual variability in infarct size was observed after occlusion of the left anterior descending coronary artery at a standardised location for a well defined period. An examination of the factors responsible for this variability was carried out in order to develop a statistical model which would make it possible to predict infarct size. Using multiple regression analysis, it was found that in most protocols (except 90 min thrombosis) more than 85% of the variability in infarct size could be explained by the size of the area at risk and the amount of collateral flow. Thus, knowing the area at risk and the collateral flow, a fairly accurate prediction can be made of the size of the infarct that the dog will develop after a defined occlusion period. Furthermore, it was found that the infarct size increased with duration of occlusion, while duration of reperfusion had no effect. In the 90 min occlusion group thrombosis induced a larger final infarct than ligature. CONCLUSIONS: A correction for baseline variables is necessary in order to compare infarct size between experimental groups. The usefulness of this procedure is shown by an example of an experimental intervention, i.e., R 56,865, a drug with known cardioprotective effects.

Animals↗
PubMed2005

High-frequency components of auditory evoked potentials are detected in responsive but not in unconscious patients.

BACKGROUND: The dose-dependent suppression of midlatency auditory evoked potentials by general anesthetics has been proposed to measure depth of anesthesia. In this study, perioperatively recorded midlatency auditory evoked potentials were analyzed in a time-frequency space to identify significant changes induced by general anesthesia. METHODS: Perioperatively recorded auditory evoked potentials of 19 patients, recorded at varying levels of anesthesia, were submitted to a multiscale analysis using the wavelet analysis. Energy contents of the signal were calculated in frequency bands 0-57.1 Hz, 57.1-114.3 Hz, 114.3-228.6 Hz, and 228.6-457.1 Hz. A Friedman test and a Dunn multiple comparisons test were performed to identify significant differences. RESULTS: Statistical evaluation showed a highly significant decrease of the wavelet energies for the frequency bands 57.1-114.3 Hz (P < 0.0001), 114.3-228.6 Hz (P < 0.0001), and 228.6-457.1 Hz (P < 0.0001) for the measuring points representing deep general anesthesia. This decrease is accompanied by a decrease in the wavelet energy of the frequency band 0-57.1 Hz of no statistical significance (P = 0.021) (level of significance set to P = 0.01). The changes are most prominent in the poststimulus interval between 10 and 30 ms. CONCLUSIONS: This study describes the presence of high-frequency components of the auditory evoked potential. The amount of these components is higher during responsiveness when compared to unconsciousness. Temporal localization of the high-frequency components within the auditory evoked potential shows that they represent a response to the auditory stimulus. Further studies are required to identify the source of these high-frequency components.

Acoustic Stimulation↗
PubMed2002

Unconscious masked priming depends on temporal attention.

The cognitive processes at work in masked priming experiments are usually considered automatic and independent of attention. We provide evidence against this view. Three behavioral experiments demonstrate that the occurrence of unconscious priming in a number comparison task is determined by the allocation of temporal attention to the time window during which the prime-target pair is presented. Both response-congruity priming and physical repetition priming vanish when temporal attention is focused away from this time window. These findings are inconsistent with the concept of a purely automatic spreading of activation during masked priming.

Adult↗
PubMed2000

Unconscious violinists and the use of analogies in moral argument.

Analogies are the stuff out of which normative moral philosophy is made. Certainly one of the most famous analogies constructed by a philosopher in order to argue for a specific controversial moral conclusion is the one involving Judith Thomson's unconscious violinist. Reflection upon this analogy is meant to show us that abortion is generally not immoral even if the prenatal have the same moral status as the postnatal. This was and still is a controversial conclusion, and yet the analogy does seem to reveal in a very vivid way what makes abortion a reasonable response to a terrible situation. But Thomson's example has frequently been attacked on all sides for not being truly analogous to abortion. Here I develop a brand new analogy that sheds light on the issue with which Thomson was concerned, while at the same time avoiding most of the more serious objections made to her analogy.

Abortion, Induced↗
PubMed2002

Direct comparison of neural systems mediating conscious and unconscious skill learning.

Procedural learning, such as perceptual-motor sequence learning, has been suggested to be an obligatory consequence of practiced performance and to reflect adaptive plasticity in the neural systems mediating performance. Prior neuroimaging studies, however, have found that sequence learning accompanied with awareness (declarative learning) of the sequence activates entirely different brain regions than learning without awareness of the sequence (procedural learning). Functional neuroimaging was used to assess whether declarative sequence learning prevents procedural learning in the brain. Awareness of the sequence was controlled by changing the color of the stimuli to match or differ from the color used for random sequences. This allowed direct comparison of brain activation associated with procedural and declarative memory for an identical sequence. Activation occurred in a common neural network whether initial learning had occurred with or without awareness of the sequence, and whether subjects were aware or not aware of the sequence during performance. There was widespread additional activation associated with awareness of the sequence. This supports the view that some types of unconscious procedural learning occurs in the brain whether or not it is accompanied by conscious declarative knowledge.

Adult↗
PubMed1980

Is there an unconscious national conspiracy against children in the United States?

The author's thesis is that there is indeed an unconscious national conspiracy against children in our country. He presents data in relation to seven areas in which children function, to support his thesis. He then proposes an approach to understanding how this state of affairs has come about and makes specific recommendations that he feels will help us move toward a solution to this problem.

Adolescent↗
PubMedDate not supplied

Early parenteral nutrition in patients unconscious because of acute drug poisoning.

The author studied the clinical and laboratory effects of early parenteral nutrition (EPN) in patients who were comatose as a result of acute drug poisoning. All patients were unconscious at the time of admission and entry into the study and received our usual conservative therapy for the first 24 hours. Alternate patients received an EPN solution containing amino acids and glucose. Volume, composition, and caloric content of the EPN solution were calculated separately for each patient according to weight and height nomograms. It was found that the group receiving EPN (n = 46) normalized their nitrogen balance sooner and demonstrated a consistent decrease in their creatine phosphokinase level. Serum amino acid values in patients treated with EPN did not change significantly during the treatment trial. The control group (n = 40) demonstrated a significantly lower serum amino acid concentration on the third day of treatment (p < .001), had significantly more pneumonias (p < .05), and their hospitalization time was significantly longer (.01 < p < .05) than the EPN group. There were significantly fewer instances of disseminated intravascular coagulation in the group receiving EPN (p < .05).

Adolescent↗
PubMed1975

Endotracheal antibiotics for the prevention of tracheobronchial infections in tracheotomized unconscious patients. A comparative study of gentamicin and aminosidin-polymyxin B combination.

Endotracheal administration of gentamicin has been compared to the endotracheal administration of aminosidin plus polymyxin B as a preventive measure against tracheobronchial infections in 25 and 22 tracheotomized patients respectively who had been admitted to a neurosurgical unit. Both series were comparable as far as underlying disease, duration of hospitalization, surgical therapy. Both regimens were similarly effective from the bacteriologic and clinical points of view. Both regimens were similarly effective in preventing colonization of bronchial secretions by potential pathogens and were associated with a similar frequency of infectious episodes (eight in each group). The use of aminosidin-polymyxin B combination was associated with a lower incidence of emergence of gentamicin resistant strains, but the endotracheal administration of gentamicin was better tolerated than that of the combination. It is concluded that the combination of aminosidin-polymyxin is a useful alternative to gentamicin for the prevention of bronchopulmonary infections in unconscious tracheotomized patients.

Adolescent↗
PubMed1999

Unconsciously controlled processing: the Stroop effect reconsidered.

The Stroop effect is widely considered to be compelling evidence that an acquired skill such as reading is "automatic" in the sense that lexical/semantic analyses of single words cannot be prevented, even when they are irrelevant and harmful to the task at hand. This view is challenged by a series of three experiments in which the presence/absence of a Stroop effect depends on (1) whether all of the target elements are colored or not, in conjunction with (2) whether the target and the spatially distinct color word distractor belong to the same domain or not. A framework is offered in which domain-specific encoding algorithms play a major role. Skilled word recognition is typically unconscious, but is characterized better as contextually controlled, rather than "automatic."

Association↗
PubMed1994

[The effects of unconscious processing of hostility-related words and physiological arousal upon person perception].

The purpose of the present study was to examine the effects of the physiological arousal and the prior subconscious processing of hostility-related words upon the cognitive complexity in person perception. First, sixteen male and 16 female college students performed a cognitive task in which they processed hostility-related words or neutral words unconsciously in a high arousal or a normal arousal state. In the second ostensibly unrelated task, the subjects were presented with an ambiguous description of target person's mild hostile behavior and they were asked to rate the impression of the target person on several SD-trait scales. It was found that the higher the subjects' arousal level was, the simpler the cognitive complexity became. Also, when the subjects processed neutral words in the high arousal state, individual differences of the impression were the largest. The effects of hostility-related words to decrease the individual differences in the high arousal state, however, were not found. These results indicate that physiological arousal may have an important role in the mechanisms of social cognition.

Adult↗
PubMed2000

Knowledge as an emotional and intellectual realization of the unconscious. Gnosiology, Psychedelic Drugs and Prenatal Experiences*

The use of psychedelic drugs in minute doses as an adjuvant psychotherapeutic means, within the context of Athanassios Kafkalides' autopsychognosia, caused the emotional revival of prenatal and perinatal experiences. This mnemonic process gives rise to a wide range of gnosiological questions such as, inter alia, those regarding the use of psychedelic drugs to stimulate memories and the difference between emotional and intellectual realization in the quest for knowledge. The new findings in this field necessitated profound changes of concepts like truth, reality, subjectivity, objectivity, unconscious, consciousness, cause and effect, emotions, intellect, quality, quantity, etc. The study presented here will deal with these issues in the context of gnosiotheoretical stands supported by thinkers from Plato to Feyerabend.

Journal Article↗
PubMed2005

Successful surgical treatment of rupture of coronary arteriovenous fistula with unconsciousness after chest and back pain.

A 65 year-old woman was admitted to our hospital, because of unconsciousness after chest and back pain. Echocardiography showed pericardial effusion. She suffered from pre-shock due to cardiac tamponade. Although a cause of cardiac tamponade was unclear, we performed emergency surgical treatment without coronary angiography. In operation, we found a rupture of coronary arteriovenous fistula and repaired it. The patient recovered from the surgery uneventfully. Coronary artery fistula is an abnormal communication between a coronary artery and a cardiac chamber or major vessel. It is the most common congenital anomalies of the coronary arteries. Many patients with these anomalies remain asymptomatic, but some patients develop symptoms of congestive heart failure, infective endocarditis, myocardial ischemia, arrhythmia, or rupture of an aneurismal fistula. Usually, the dilatation of fistula is common, and although 19% of this may become aneurysmal, the rupture of the aneurysm is very rare. We report a case of ruptured coronary arteriovenous fistula who underwent successful emergent surgery.

Aged↗
PubMed2006

[Significance of the cognitive context in formation of unconscious visual sets].

The experimental evidence that the cognitive set shifting in healthy humans depends on the context of cognitive performance is discussed. Lability/rigidity of the experimentally formed unconscious visual set is largely determined by the type of additional task ("what?" or "where?", i. e., stimulus recognition or spatial localization, respectively) introduced into the context of the experiment. It is suggested that the acquired set more readily shifts to a new one more adequate to modified conditions in case of alternation of the ventral and dorsal visual pathways involved in the information processing in the context of cognitive performance.

Brain↗
PubMed1977

Rectal perchlorate for unconscious patients prior to brain scintigraphy with pertechnetate: concise communication.

Patients undergoing brain scintigraphy with pertechnetate are frequently premedicated with oral perchlorate. However, the oral route is difficult to employ in unconscious or uncooperative patients or when oral intake is restricted. In such situations, rectal administration of sodium perchlorate dissolved in water is an effective alternative to oral administration.

Brain Diseases↗