Dreaming: cognitive processes during cortical activation and high afferent thresholds.

The concepts of nonlocal, or distributed, cortical and cognitive activation are examined for their usefulness in describing the relations between sleep and waking neurocognitive processes. Changes in the pattern of distributed activation and inhibition of selected portions of sensory, cognitive, and motor decision modules account for the differences in imagery and thought across sleep and waking states in comparable environments. The massive inhibition of sensory and proprioceptive input to perceptual modules in Stage 1 REM sleep leaves the perceptual and cognitive modules, by default, with their own output as their sole input. Given this constraint, the activation of portions of the cortical structures that execute waking perceptual, cognitive and motor responses is necessary and sufficient to produce the imagery and thought of dreaming sleep. Connectionist models are introduced so that neurophysiological and cognitive concepts of distributed and local activation and inhibition can be translated into a common language, and in so doing, are used to simulate several processes fundamental to the production of imaginal thought and dreaming.

Sleeping and waking thought: effects of external stimulation.

This article describes some of the variables that distinguish waking and sleeping (REM) thought. Mentation reports from the waking state, as described here, tend to have more topic shifts than those from the REM state, which often have a single-theme storylike quality. It is assumed that heightened response thresholds to sensory stimuli, in conjunction with the state of high cortical activation typical of REM sleep, account for the storylike quality of REM imagery. In this experiment, an intermittent auditory stimulus was the model for environmental influences on waking mentation. It was hypothesized that the removal of this intermittent auditory stimulation, simulating in waking subjects the increased sensory thresholds of REM sleep, would decrease the number of topic shifts in spontaneous thought. It was expected that this reduction in number of topics would approach levels achieved in REM sleep. Thirty subjects participated in individual sessions in which they lay in a sound-attenuated, lightproof room with eyes closed. They were asked for mentation reports as follows: after lying awake with external stimulation (W), after lying awake without external stimulation (WO), and after being wakened from REM sleep. Transcribed mentation reports were scored on seven content rating scales, including total recall count, a count of all words in which the subject was describing his/her experience during the previous interval, and number of thought units (TU) per report, a count of the distinct, thematically homogeneous thought sequences. Hotelling t-squared tests were performed with the different states as the independent variables and the scores on the cognitive scales as the dependent variables. The major factor distinguishing mentation reports of waking subjects and subjects wakened from REM sleep was the TU count, with waking subjects changing topics more frequently. Removal of the intermittent auditory stimulus reduced the number of topic shifts in waking subjects, with a significance approaching the 95% confidence limit.

Pattern of breathing during upper gastrointestinal endoscopy: implications for administration of supplemental oxygen.

Cardiopulmonary complications account for half the deaths associated with upper gastrointestinal endoscopy. The incidence of hypoxia at the time of upper gastrointestinal endoscopy can be greatly reduced by the administration of supplemental oxygen via nasal cannulae. Using dual thermistors in the mouth and nostrils of patients undergoing upper gastrointestinal endoscopy, the present study demonstrates that most patients breathe predominantly via the oral, rather than the nasal, route following intubation of the oesophagus. The implication from the study is that, if supplemental oxygen is to be used in 'at risk' patients, it would be logical to employ an oral, rather than nasal, route of administration.

Bolus or slow titrated injection of midazolam prior to upper gastrointestinal endoscopy? Relative effect on oxygen saturation and prophylactic value of supplemental oxygen.

A total of 131 patients undergoing upper gastrointestinal endoscopy were sedated with midazolam given as a bolus injection over 5 seconds. The oxygen saturation was continuously measured using a pulse oximeter. Supplemental oxygen was given via nasal cannulae at a rate of 3 litres per minute to 54 patients, while the remaining 77 patients only received oxygen if their oxygen saturation dropped below 85%. Both groups in the present series were compared with 3 previously published series of patients, in whom we had used intravenous midazolam as a slow titrated injection. Despite using on average only two-thirds of the dose of midazolam, following bolus injection the degree of oxygen desaturation during the endoscopic procedure was greater, and the ability of supplemental oxygen delivered via nasal cannulae to prevent hypoxia was less (P less than 0.01), than with a slow titrated injection.

Case report. Mini-epidemic of thyrotoxicosis occurring in physicians.

This report describes the appearance of thyrotoxicosis over the past eight years in three male physicians working in the Division of Endocrinology at The Mount Sinai Hospital. Since no other instances of hyperthyroidism developed among the hospital medical or dental attending staff, to the authors' knowledge, during the years of 1953-1973, this incidence appears to indicate an unusual occurrence. (Information regarding other possible instances of thyrotoxicosis was obtained by questioning all of the physicians in the Division of Endocrinology at The Mount Sinai Hospital, members of the Division of Endocrinology at the other major institutions in the city and, finally, inquiry of the physicians in the Department of Medicine at The Mount Sinai Hospital.)

Provision for advanced pain management techniques in adult palliative care: a national survey of anaesthetic pain specialists.

INTRODUCTION: It is estimated that 8% of cancer patients could benefit from advanced pain management techniques; some 12,000 patients per year in the UK. In 2002, Linklater et al. surveyed palliative medicine consultants to assess their access and attitude to such techniques, finding under-utilization with a lack of formal arrangements for referral. We report a survey of pain specialist anaesthetists on the same topic. METHOD: Postal questionnaire survey of lead anaesthetists in UK pain clinics. RESULTS: 106 responses were received from 170 questionnaires sent (62%). Referral rates from palliative medicine to pain clinics were low; only 31% of respondents received more than 12 per year. Joint consulting arrangements were rare, but were associated with more referrals. Only 25% of anaesthetists' job plans had time allocated for palliative medicine referrals, but where present this correlated positively with referrals received (P <0.002). Total interventions were estimated at less than 1000 per year. DISCUSSION: There is evidence of under-referral of patients for advanced pain management procedures with a lack of integrated services.

Anxiety and informed consent. Does anxiety influence consent for inclusion in a study of anxiolytic premedication?

Forty-three consecutive patients were interviewed on the eve of elective gynaecological surgery to determine the effect of anxiety on the granting of informed consent to participate in an hypothetical study. Anxiety was assessed using the Spielberger state-trait anxiety inventory and 10-cm linear analogue scale. A standardised explanation of an hypothetical premedication study was given and the patients' consent requested. Results were grouped for those who granted (n = 33) and those who withheld (n = 10) consent: anxiety scores for the latter were significantly higher (p less than 0.01). It is concluded that patients with high pre-operative anxiety levels are more likely to withhold consent for inclusion in premedication studies than are those who are less anxious. Seeking informed consent would introduce bias into studies of anxiolytic premedication.

The primary deformity in hallux valgus and metatarsus primus varus.

Analysis of radiographs from patients with hallux valgus showed that following surgical correction there were statistically significant reductions in the hallux valgus, intermetatarsal, and metatarsus primus varus angles. Normal values for these angles were established from a control group of asymptomatic feet and from previously published reviews. If the metatarsus primus varus deformity returns to normal following correction of the hallux valgus by a procedure that does not directly realign the metatarsal, the deformity must be secondary to hallux valgus. This is of importance in planning surgical procedures for the correction of these deformities and confirms the relative popularity and success of distal metatarsal osteotomies. Any operation designed to correct both hallux valgus and metatarsus primus varus must aim to correct the primary hallux valgus lesion rather than the secondary metatarsal deviation.

Cortical arousal and mentation in sleeping and waking subjects.

Cognitive variables and cortical arousal levels were examined in order to determine whether differences in cortical arousal levels within REM and waking could account for different aspects of mentation derived from the two states. Cognitive variables were derived from mentation reports collected from 30 subjects in both the waking state and after being awakened from REM sleep. Mentation reports were independently scored on seven content rating scales, by two judges blind to the conditions. These scales include among others, Total Recall Count (TRC), a count of all words in which the subject described his/her experience during the previous interval. The EEG activity, obtained from left and right midtemporoparietal and central sites, was recorded for 5-min periods before obtaining mentation reports. The absolute power of the EEG activity was calculated for each of six bandwidths. EEG power data from both waking and REM were entered into multiple linear regression equations to predict TRC. No relationships were found between TRC and general cortical activation, as measured by the EEG. Other statistical analyses, including relationships between EEG and scales of visual imagery, are discussed.

The effect of presemantic acoustic adaptation on semantic "satiation".

A decrement in the strength of the meaning of a word after rapid repetition of that word has been called "semantic satiation." This study asked whether this "satiation" might be produced by presemantic acoustic adaptation. Category words were utilized to prime the meaning of target words. The adaptation or "satiation" procedure, 30 rapid repetitions of the primes, was compared with a control condition of 3 repetitions. Participants listened to a series of prime words, each repeated by either the same speaker or many speakers, and then made semantic decisions on target words. When all the repetitions of a prime word are produced by the same speaker, presemantic and semantic repetitions are confounded. When the repetitions are produced by different speakers, presemantic acoustic repetition is abolished. A semantic decrement was detected with single-speaker, but not with multiple-speaker, repetitions of prime words. This study concluded that the semantic "satiation" observed here was a decrement in the activation level of semantic representations induced by presemantic acoustic adaptation.

Dreaming in the late morning: summation of REM and diurnal cortical activation.

Since the discovery that the characteristics of dreaming sleep are far stronger in Stage 1 rapid eye movement (REM) sleep than in any other biological state, investigators have attempted to determine the relative responsibility of the tonic versus the phasic properties of REM sleep for the different characteristics of dreaming--features such as the amount of information in the dream report, the brightness and clarity of the visual images, shifts in thematic continuity, and incongruities of image and meaning. The present experiment is designed to identify dream characteristics that are specifically associated with tonic changes in level of cortical activation within sleep. It samples reports of imagery and thought during spontaneous variations within one phase of the 24-h diurnal rhythm and across the REM-NREM (non-REM) sleep cycle in order to identify the independent and joint contributions of the two cycles to imagery and thought. The rising phase of the diurnal cycle in the late night and morning was estimated from clock time during the late night and early morning and was varied by delaying the sleep onset and waking time of the subjects. Considered together with other studies, the results suggest that the major determinant of vivid visual imagery and enhanced cognitive activity during sleep is a pattern of subcortical and cortical activation that is common to both the REM phase of the REM-NREM cycle and the activated phase of the 24-h diurnal wake-sleep cycle.

EEG asymmetry and sleep mentation during REM and NREM.

The hypothesis that dreaming is mediated by the right hemisphere was evaluated by monitoring EEG power asymmetry during REM and NREM sleep, and obtaining mentation reports when short-term temporal shifts in the EEG indicated relative left- or right-hemispheric dominance. Content analyses provided no support for the right-hemisphere hypothesis; indeed, some scales showed higher content during relative left-hemispheric dominance. In contrast to earlier reports, no difference between REM and NREM in EEG asymmetry was observed.

Midazolam-droperidol premedication for cardiac surgery. A comparison with papaveretum and hyoscine.

A combination of midazolam and droperidol given intramuscularly was compared with papaveretum and hyoscine for premedication of patients about to undergo cardiac surgery. Midazolam and droperidol proved to be a very satisfactory combination, producing superior sedation and anxiolysis with good cardiovascular stability.

An open study to compare the pharmacokinetics, safety and tolerability of a multiple-dose regimen of azithromycin in young and elderly volunteers.

An open, parallel study was conducted to compare the pharmacokinetics of oral azithromycin in young and elderly healthy volunteers. A total of 12 young subjects (six males, six females) with a mean age of 29 (range 22-39) years and another 12 elderly subjects (six males, six females) with a mean age of 72 (range 67-80) years were given a standard five-day therapeutic regimen of azithromycin (500 mg single dose on day 1 and 250 mg once daily on days 2-5). Pharmacokinetic results indicated that Cmax, Cmin and urinary excretion were similar in the two age groups. Mean AUC0-24 was significantly greater (2.7 micrograms.h/ml) at day 5 in the elderly subjects compared with the younger age group (AUC0-24 = 2.1 micrograms.h/ml) (p = 0.041). Similarly, tmax values on days 1 and 5 were significantly greater in the elderly subjects; 3.8 h compared with 2.5 h in young subjects (p = 0.005) on day 1 and 4.4 h, compared with 3.2 h (p = 0.047) on day 5. There was also evidence of an inverse relationship between creatinine clearance and AUC0-24 (p less than 0.01) but not urinary excretion or Cmax. Despite these observations, it is concluded that the differences between the two age groups were of insufficient magnitude to warrant a dose modification in elderly subjects with only mild renal impairment. Side effects, chiefly headache and gastrointestinal symptoms, were reported by seven subjects in each group. No subject, however, was withdrawn from the study and there were no treatment-related abnormalities in any of the laboratory parameters measured.

Upper gastrointestinal endoscopy: a prospective randomized study comparing continuous supplemental oxygen via the nasal or oral route.

We have examined the efficacy of supplemental oxygen in preventing episodes of significant arterial desaturation (SpO2 less than 90%) during upper gastrointestinal endoscopy. We have compared the effects of 2 liters.min-1 of oxygen given orally via the bite-guard with the same flow rate via nasal cannulas and have also examined the effects of pre-oxygenation. Results of this study at a flow rate of 2 liters.min-1 have been compared with previously published results at a flow rate of 3 liters.min-1. Although in this study fewer episodes of desaturation were seen in the orally supplemented group compared with the nasal group, the difference observed was not statistically significant. Pre-oxygenation significantly reduced episodes of desaturation (SpO2 less than 90%, p less than 0.01) and prevented SpO2 falls below 85% in all patients studied. Supplemental oxygen given at a rate of 2 liters.min-1 was as effective as that given at a rate of 3 liters.min-1 in preventing significant desaturation, as previously defined, during the procedure. We therefore recommend the use of supplemental oxygen at a flow rate of 2 liters.min-1 in all high risk patients and conclude that the oral route has practical advantages and is at least as effective as nasal cannulas.

REM sleep eye movement counts correlate with visual imagery in dreaming: a pilot study.

Based on the findings of our previously published positron emission tomography study, we proposed that recorded eye movements during REM sleep are visually targeted saccades. In the present study, we examined the correlation between the number of eye movements in REM sleep (EM) and visual imagery in dreaming (V) and provided further support for our proposal. All the observations (N = 11) were made with one individual to eliminate interindividual variation and were made during the second REM sleep period to control for a time-of-night effect. V, with or without dream report length partialled out, was strongly associated with EM only in the 1-min interval immediately preceding awakening. The time course of the association suggests that the strong EM-V association reflects a phasic, localized activation of the eye-movement-control system in association with REM sleep eye movements.