Parallel brain systems for learning with and without awareness.
(17/1787)
A fundamental issue about memory and its different forms is whether learning can occur without the development of conscious knowledge of what is learned. Amnesic patients and control subjects performed a serial reaction time task, exhibiting equivalent learning of an imbedded repeating sequence as measured by gradually improving reaction times. In contrast, four tests of declarative (explicit) knowledge indicated that the amnesic patients were unaware of their knowledge. Moreover, after taking the tests of declarative memory, all subjects continued to demonstrate tacit knowledge of the repeating sequence. This dissociation between declarative and nondeclarative knowledge indicates that the parallel brain systems supporting learning and memory differ in their capacity for affording awareness of what is learned. (+info)
Vehicle accidents related to sleep: a review.
(18/1787)
Falling asleep while driving accounts for a considerable proportion of vehicle accidents under monotonous driving conditions. Many of these accidents are related to work--for example, drivers of lorries, goods vehicles, and company cars. Time of day (circadian) effects are profound, with sleepiness being particularly evident during night shift work, and driving home afterwards. Circadian factors are as important in determining driver sleepiness as is the duration of the drive, but only duration of the drive is built into legislation protecting professional drivers. Older drivers are also vulnerable to sleepiness in the mid-afternoon. Possible pathological causes of driver sleepiness are discussed, but there is little evidence that this factor contributes greatly to the accident statistics. Sleep does not occur spontaneously without warning. Drivers falling asleep are unlikely to recollect having done so, but will be aware of the precursory state of increasing sleepiness; probably reaching a state of fighting off sleep before an accident. Self awareness of sleepiness is a better method for alerting the driver than automatic sleepiness detectors in the vehicle. None of these have been proved to be reliable and most have shortcomings. Putative counter measures to sleepiness, adopted during continued driving (cold air, use of car radio) are only effective for a short time. The only safe counter measure to driver sleepiness, particularly when the driver reaches the stage of fighting sleep, is to stop driving, and--for example, take a 30 minute break encompassing a short (< 15 minute) nap or coffee (about 150 mg caffeine), which are very effective particularly if taken together. Exercise is of little use. CONCLUSIONS: More education of employers and employees is needed about planning journeys, the dangers of driving while sleepy, and driving at vulnerable times of the day. (+info)
Violence in inpatients with schizophrenia: a prospective study.
(19/1787)
Accurate evaluations of the dangers posed by psychiatric inpatients are necessary, although a number of studies have questioned the accuracy of violence prediction. In this prospective study, we evaluated several variables in the prediction of violence in 63 inpatients with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder. Nurses rated violent incidents with the Overt Aggression Scale. During hospitalization, sociodemographic variables, clinical history, neurological soft signs, community alcohol or drug abuse, and electroencephalographic abnormalities did not differ between violent and nonviolent groups. Violent patients had significantly more positive symptoms as measured by the Positive and Negative Syndrome Scale (PANSS), higher scores on the PANSS general psychopathology scale, and less insight in the different constructs assessed. A logistic regression was performed to discriminate between violent and nonviolent patients. Three variables entered the model: insight into symptoms, PANSS general psychopathology score, and violence in the previous week. The actuarial model correctly classified 84.13 percent of the sample; this result is significantly better than chance for the base rate of violence in this study. At hospital admission, clinical rather than sociodemographic variables were more predictive of violence. This finding has practical importance because clinical symptoms are amenable to therapeutic approaches. This study is the first to demonstrate that insight into psychotic symptoms is a predictor of violence in inpatients with schizophrenia. (+info)
Detection and control of high blood pressure in the community : Do we need a wake-up call?
(20/1787)
At the community level, the effect of national programs in increasing hypertension awareness, prevention, treatment, and control is unclear. This study evaluated the degree of detection and control of high blood pressure in a random population-based sample of Olmsted County, Minnesota, residents >/=45 years old, of whom 636 subjects among 1245 eligible residents agreed to participate. Home interview and home and office measurements of blood pressure were used to estimate awareness, treatment, and control rates for hypertension in the community. Mean blood pressures (+/-SD) were 138/80+/-20/12 mm Hg for men and 137/76+/-23/11 mm Hg for women. The overall prevalence of hypertension was 53%. The percentage of subjects with treated and controlled hypertension was 16.6%. Thirty-nine percent of subjects were unaware of their hypertension. Despite clinical trial evidence of reduced morbidity and mortality with antihypertensive therapy, recently reported national data suggest a leveling-off trend for treatment and control of hypertension. This population-based study supports these observations and suggests that at a community level, hypertension awareness and blood pressure control rates are suboptimal, presumably because of decreased attention to the detection and control of hypertension. (+info)
Association between health-related knowledge and the awareness of blood pressure readings. Japan Lifestyle Monitoring Study Group.
(21/1787)
This study aims to evaluate the relationships between awareness of blood pressure testing and health-related knowledge. Among 9 blocks in Japan, one or two areas were selected and a questionnaire survey including physical activity, nutrient intake, drinking habits, smoking habits, medical history, annual frequency of blood pressure testing, subjective sense of wellness, and health related knowledge was conducted. Respondents' sex and age were adjusted as potential confounding factors and the association between possession of health-related knowledge and awareness of blood pressure testing were examined by using a multiple logistic regression model. Among the 1,834 effective responses, 263 (14.3%) answered that they could state their blood pressure levels. These individuals tended to have a greater health-related knowledge. Even after adjusting for other potential confounders (smoking habits, medical history, annual frequency of blood pressure testing, and subjective sense of wellness) health-related knowledge were significantly related to blood pressure awareness. (+info)
Attention without awareness in blindsight.
(22/1787)
The act of attending has frequently been equated with visual awareness. We examined this relationship in 'blindsight'--a condition in which the latter is absent or diminished as a result of damage to the primary visual cortex. Spatially selective visual attention is demonstrated when information that stimuli are likely to appear at a specific location enhances the speed or accuracy of detection of stimuli subsequently presented at that location. In a blindsight subject, we showed that attention can confer an advantage in processing stimuli presented at an attended location, without those stimuli entering consciousness. Attention could be directed both by symbolic cues in the subject's spared field of vision or cues presented in his blind field. Cues in his blind field were even effective in directing his attention to a second location remote from that at which the cue was presented. These indirect cues were effective whether or not they themselves elicited non-visual awareness. We concluded that the spatial selection of information by an attentional mechanism and its entry into conscious experience cannot be one and the same process. (+info)
Nitrous oxide does not alter bispectral index: study with nitrous oxide as sole agent and as an adjunct to i.v. anaesthesia.
(23/1787)
We have studied the effect of nitrous oxide on bispectral index (BIS), calculated from a bipolar encephalogram. Inhalation of 70% nitrous oxide resulted in loss of consciousness in all healthy volunteers (n = 10) but no change in BIS. Brief inhalation up to 1.2% sevoflurane also resulted in loss of consciousness in volunteers (n = 5), but with sevoflurane, BIS decreased. BIS and the haemodynamic effects of adding nitrous oxide were also measured during coronary artery bypass surgery in patients (n = 10) receiving midazolam and fentanyl infusions. Measurements were made after 0%, 33%, 66% and 0% nitrous oxide, just before skin incision and after sternotomy. Nitrous oxide caused no change in BIS. BIS may indicate a sufficient hypnotic depth to prevent awareness during surgery, but our study demonstrated that pharmacological unconsciousness-hypnosis can also be reached by mechanisms to which BIS is not sensitive. Thus BIS is a sufficient but not a necessary criterion for adequate depth of anaesthesia or prevention of awareness. (+info)
Visual experience during phacoemulsification cataract surgery under topical anaesthesia.
(24/1787)
BACKGROUND/AIMS: Visual awareness during phacoemulsification cataract surgery is an important determinant of patient satisfaction with any anaesthetic technique. Topical anaesthesia could be associated with significant visual awareness because it does not affect optic nerve function. METHODS: The visual experience during phacoemulsification cataract surgery under topical anaesthesia (without sedation) was assessed for 106 consecutive unselected patients. Patients were interviewed immediately after surgery using a standardised questionnaire that explored specific aspects of their visual experience. RESULTS: Four patients were excluded because they had poor recollection of their visual experience. The visual awareness of the remaining 102 patients comprised operating microscope light (99), colours (73), flashes of light (7), vague movements (19), surgical instruments or other objects (12), change in light brightness during surgery (49), change in colours during surgery (30), and transient visual alteration during corneal irrigation (25). No patient found their visual experience during surgery unpleasant, though the operating microscope light was uncomfortably bright for two patients. Six patients lost light perception for a short interval during surgery. There was no association between the various visual phenomena reported and patients' age, sex, preoperative visual acuity, cataract morphology, coexisting ocular pathology, or previous experience of cataract surgery under local anaesthesia (p>0.05). CONCLUSIONS: Patients experience a wide variety of visual sensations during phacoemulsification cataract surgery under topical anaesthesia. Topical anaesthesia does not, however, appear to result in greater visual awareness than regional anaesthesia. Preoperative patient counselling should include information about the visual experience during surgery. (+info)