Parallel acquisition of awareness and trace eyeblink classical conditioning.
(49/1787)
Trace eyeblink conditioning (with a trace interval >/=500 msec) depends on the integrity of the hippocampus and requires that participants develop awareness of the stimulus contingencies (i.e., awareness that the conditioned stimulus [CS] predicts the unconditioned stimulus [US]). Previous investigations of the relationship between trace eyeblink conditioning and awareness of the stimulus contingencies have manipulated awareness or have assessed awareness at fixed intervals during and after the conditioning session. In this study, we tracked the development of knowledge about the stimulus contingencies trial by trial by asking participants to try to predict either the onset of the US or the onset of their eyeblinks during differential trace eyeblink conditioning. Asking participants to predict their eyeblinks inhibited both the acquisition of awareness and eyeblink conditioning. In contrast, asking participants to predict the onset of the US promoted awareness and facilitated conditioning. Acquisition of knowledge about the stimulus contingencies and acquisition of differential trace eyeblink conditioning developed approximately in parallel (i.e., concurrently). (+info)
Reappraising insight in psychosis. Multi-scale longitudinal study.
(50/1787)
BACKGROUND: Many patients suffering from psychosis are unaware of their disorder and symptoms. AIMS: To investigate whether insight changes with time, and how it relates to patients' psychopathology, and to examine the correlations between insight scales in patients with psychoses. METHODS: Seventy-five consecutively admitted in-patients with schizophrenia, affective disorder with psychotic symptoms, or schizoaffective disorder were examined after remission of an acute episode and at follow-up (> 6 months). Three different scales were used to assess insight. RESULTS: To some extent, insight into past episodes improved over time in patients with psychosis, regardless of diagnosis. Few significant relationships between insight and psychopathology remained stable at follow-up. The higher the negative and disorganisation dimensions at baseline, the less did attitudes to treatment vary when tested at follow-up. No predictive value for variability of psychopathological dimensions was found for insight dimensions. The insight scales used were highly intercorrelated, suggesting that they measure the same construct. CONCLUSIONS: Insight and psychopathology seem to be semi-independent domains. (+info)
Postnatal development of the motor representation in primary motor cortex.
(51/1787)
The purpose of this study was to examine when the muscles and joints of the forelimb become represented in primary motor cortex (M1) during postnatal life and how local representation patterns change. We examined these questions in cats that were anesthetized (45-90 days, n = 14; adults, n = 3) and awake (n = 4; 52-86 days). We used intracortical microstimulation (45 ms duration train, 330 Hz, 0.2-ms balanced biphasic pulses, with a leading cathodic pulse; up to 100 microA). In young animals (less than day 70), we also used stimulus trains and pulses that could produce greater temporal summation (up to 200-ms train duration, down to 143-Hz stimulus frequency, up to 0.8-ms pulse width). Anesthetized animals were areflexic, and muscle tone was similar to that of the awake cats (i.e., relaxed, not weight or load bearing, with minimal resistance to passive stretch). We monitored the kinematic effects of microstimulation and changes in electromyographic (EMG) activity in forelimb muscles. There was an age-dependent reduction in the number of sites where microstimulation did not produce a motor effect (i.e., ineffective sites), from 95% in animals younger than 60 days to 33% between 81 and 90 days. In adults, 24% of sites were ineffective. Median current thresholds for evoking movements dropped from 79 microA in animals younger than day 60 to 38 and 28 microA in day 81-90 animals and adults, respectively. There was a proximal-to-distal development of the somatotopic organization of the motor map. Stimulation at the majority of sites in animals younger than day 71 produced shoulder and elbow movement. Wrist sites were first present by day 71, and digit sites by day 81. Sites at which multiple responses were evoked, between 1.0 and 1.5 times threshold, were present after day 71, and increased with age. A higher percentage of distal joints were co-represented with other joints, rather than being represented alone. We found that effective sites initially were scattered and new sites representing proximal and distal joints filled in the gaps between effective sites. During most of the period examined, development of the caudal M1 subregion lagged that of the rostral subregion (percent of effective sites; threshold currents), although these differences were minimal or absent in adults. Our results show that the M1 motor representation is absent at day 45 and, during the subsequent month, the motor map is constructed by progressively representing more distal forelimb joints. (+info)
Bispectral analysis of the electroencephalogram does not predict responsiveness to verbal command in patients emerging from xenon anaesthesia.
(52/1787)
The bispectral index (BIS) is derived empirically from the electroencephalogram database of patients receiving common anaesthetics, but it may not be valid for uncommon agents. Therefore, we investigated how xenon affects the BIS. Nine and 11 patients were anaesthetized with 0.8 of the minimal alveolar concentration (MAC) of isoflurane (0.92%) and xenon (56%), respectively. After the end of operation, these concentrations were decreased in decrements of 0.1 MAC (isoflurane 0.12% or xenon 7%) and each new concentration was maintained for 15 min. This was repeated until the patient first opened her eyes or squeezed the investigator's hand on command. Isoflurane and xenon at 0.8 MAC reduced the BIS to a median of 40 (range 36-53) and 36 (30-61), respectively. With decreasing concentrations of isoflurane, the BIS increased progressively and it reached a median of 96 (90-98) when the patients awoke. In contrast, four patients receiving xenon responded to verbal command while the BIS was below 50 [median 45 (range 41-49)]. The remaining seven patients in the xenon group awoke when their BIS was greater than 80 [median 96 (range 82-98)], but in four of them the BIS was no greater than 50 when the xenon concentration was only 0.1 MAC (7%) higher than that associated with awakening. We conclude that low BIS values (< 50) do not guarantee adequate hypnosis during xenon anaesthesia. (+info)
Making our voices heard: Why student journals are crucial.
(53/1787)
The studentBMJ has provided a forum for medical student debate for the past eight years. The issues that students need to discuss deserve dedicated journal space. Being able to comment on issues such as admissions policies and teaching styles may affect many future generations of doctors as well. As there are thousands of doctors in training world wide, the more ways available for students to express themselves, the better. A specific journal for Croatian medical students will allow a national perspective on these issues as well. (+info)
The Florida "truth" anti-tobacco media evaluation: design, first year results, and implications for planning future state media evaluations.
(54/1787)
OBJECTIVES: To outline the design and present selected findings from the evaluation of a state counter-advertising, anti-tobacco media campaign. The appropriateness of the design for states developing media evaluations is discussed. DESIGN: Four cross sectional, telephone surveys of the 12--17 year old population were used to track and monitor advertising and campaign awareness, confirmed awareness, and receptivity. The Florida baseline and one year surveys were used with two parallel national surveys in a quasi-experimental design to assess attitude and smoking related behaviour change attributable to the campaign. MEASURES: Awareness was measured by self report, confirmed awareness by unaided description, and receptivity by self reports of how well advertisements were liked, talked to friends about, and made one think about whether or not to smoke. Eleven attitude and three smoking behaviour items for Florida (treatment) and a national (control) population were compared at baseline and after 12 months. RESULTS: Significant increases in ad specific awareness, confirmed, receptivity, and campaign awareness, and confirmed awareness were reached by the sixth week. They continued to rise through the first year. No attitude and only minor behaviour differences were noted between the treatment and comparison populations at baseline. By the end of the first year, Florida youth had stronger anti-tobacco attitudes and better behaviour patterns than the comparison population. CONCLUSIONS: The industry manipulation strategy used in the Florida campaign resulted in high rates of recall, significant changes in attitudes/beliefs, and reduced rates of smoking behaviour among youth. (+info)
Fast backprojections from the motion to the primary visual area necessary for visual awareness.
(55/1787)
Much is known about the pathways from photoreceptors to higher visual areas in the brain. However, how we become aware of what we see or of having seen at all is a problem that has eluded neuroscience. Recordings from macaque V1 during deactivation of MT+/V5 and psychophysical studies of perceptual integration suggest that feedback from secondary visual areas to V1 is necessary for visual awareness. We used transcranial magnetic stimulation to probe the timing and function of feedback from human area MT+/V5 to V1 and found its action to be early and critical for awareness of visual motion. (+info)
Teaching old dogs new tricks--a personal perspective on a decade of efforts by a clinical ethics committee to promote awareness of medical ethics.
(56/1787)
To incorporate medical ethics into clinical practice, it must first be understood and valued by health care professionals. The recognition of this principle led to an expanding and continuing educational effort by the ethics committee of the Vancouver General Hospital. This paper reviews this venture, including some pitfalls and failures, as well as successes. Although we began with consultants, it quickly became apparent that education in medical ethics must reach all health care professionals--and medical students as well. Our greatest successes came in the formative years of a medical career (i.e., in medical school and residency training programmes), but other efforts were not wasted, particularly among nurses and other health care professionals. Although this is a personal review of the experience in one institution, the lessons learnt in Vancouver are applicable to the further development of medical ethics in the UK. (+info)