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Biomedical subjects

J H Gruzelier

Publications and source records attributed to J H Gruzelier.

At least 19 recordsLinked to original sources
PubMed1990

Nasopharyngeally and vertex recorded P300's in normal subjects.

The P300 waveform has been associated with cognitive activity during information processing, and the hippocampus has been discussed as a possible generator of this waveform. This being the case some would argue that it should be possible to record the P300 with a shorter latency and greater amplitude from an electrode placed as near the hippocampus as possible. Under local anaesthesia we inserted a specially constructed needle electrode through the left nostril in the recessus pharyngeus close to the hippocampus. The results did not support the hippocampal hypothesis. Nasopharyngeally recorded P300's were found to have significantly decreased amplitudes and extended latencies when compared to vertex recordings.

Adult↗
PubMed1989

Adverse changes in mood and cognitive performance of house officers after night duty.

The effects of long hours of work by junior doctors are the subject of growing concern. Experimental investigations of the effects of night duty on young doctors are few and have given inconclusive results. To measure the effects of long hours of work and reduced sleep on cognitive performance and mood 20 house officers (14 men and six women; mean age 25, range 24-35) were examined for 35 minutes in one session towards the end of a normal working day and in a second session at the same time after working for up to 31 continuous hours with reduced sleep. The order of the sessions was counterbalanced across the subjects. Each session comprised a series of cognitive tests: choice reaction time, vigilance reaction time, and haptic sorting tests and completion of a profile of mood states and a general questionnaire. After night duty there was a significant slowing in cognitive processing together with a decline in reaction times in the vigilance test. Loss of sleep contributed only to increased variability in the choice reaction time. Significant deleterious changes in mood after night duty occurred in all the mood scales after night duty. Continuous working may adversely affect the cognitive function and mood to the detriment of the welfare of doctors and their patients.

Adult↗
PubMed1987

Laterality of pain in migraine distinguished by interictal rates of habituation of electrodermal responses to visual and auditory stimuli.

Support is provided for a primary neural factor in migraine by studies in autonomic responsiveness to sensory stimuli in relation to the laterality of pain. Migraineurs with consistently lateralised headaches were found in two studies to exhibit extremes of autonomic responsiveness to sensory stimuli during the interictal phase. The direction of responsiveness was predictive of the laterality of pain; left-sided pain was associated with under-responsiveness and fast habituation, right-sided pain with over-responsiveness and slow habituation. Bipolarity in rate of habituation is consistent with a defect in a regulatory mechanism that controls regional cerebral activation such as the diffuse thalamic projection system.

Acoustic Stimulation↗
PubMed1986

Retarded habituation and lateral asymmetries in electrodermal activity in cardiovascular disorders.

Electrodermal activity was recorded bilaterally during a sequence of moderate-intensity tones in 40 cardiac patients who exhibited clinical signs of exhaustion and in 40 controls. Responsive patients were slower to habituate than responsive controls. The groups did not differ in non-specific responses. Patients also showed lateral asymmetries in amplitudes and latencies indicative of abnormalities in right hand activity. Levels of skin conductance were higher in patients largely because of an abnormal elevation of right hand levels in both responders and non-responders. The results were consistent with limbic dysfunction together with a loss of left hemispheric contralateral inhibition. The deficit in habituation and the laterality effect may relate to the role of effort and exhaustion in cardiovascular disorders.

Adult↗
PubMed1986

Persistent methodological problems with evoked potential augmenting-reducing.

Evoked potential (EP) amplitudes are known to be influenced by changes in the intensity of a visual stimulus. These EP amplitude-intensity functions have been linked to a wide variety of personality characteristics and neuro- and psychopathological conditions. Those individuals whose EP amplitudes increase in response to increasing stimulus intensity have been termed Augmenters while those exhibiting no amplitude increases or actual amplitude decrements have been referred to as Reducers. Serious methodological problems have been found with many of the procedures of evoked potential augmenting-reducing. Recently, new explanations for the EP augmenting-reducing phenomenon have been offered and attempts to counter some of our criticisms of augmenting-reducing methodology. Their report is itself characterized by a variety of problems. These problems together with those generally prevalent in the augmenting-reducing literature are discussed.

Evoked Potentials, Visual↗
PubMed1985

Pathway and hemispheric differences in the event-related potential (ERP) to monaural stimulation: a comparison of schizophrenic patients with normal controls.

Previous research has established the stability of the contralateral dominance effect of the auditory temporal N120 peak amplitude. The purpose of this experiment was to examine event-related potential (ERP) asymmetries in schizophrenia, with particular reference to this contralateral dominance phenomenon. Ten unmedicated schizophrenic patients and ten controls heard a series of monaural tones, with no task requirements, while EEG was recorded from Cz, Pz, T3, and T4 referred to linked earlobes. Patients were characterized by smaller N120 amplitudes than controls, an effect that was slightly more pronounced at temporal sites. Patients failed to show the normal N120 contralateral dominance effect. Hemisphere asymmetry ratios revealed that 50% of the patients showed ipsilateral dominance in the auditory pathways. Furthermore, the hemisphere asymmetries (whether ipsilaterally or contralaterally dominant) seen in patients were significantly greater than for controls. These data offer a new level of explanation for schizophrenic performance abnormalities in dichotic listening paradigms and an explanation for for the apparent dichotomy in patient performance between exaggerated right ear advantage (REA) and left ear advantage (LEA).

Acoustic Stimulation↗
PubMed1985

Psychophysiological evidence for a state theory of hypnosis and susceptibility.

Psychophysiological evidence is presented of altered cerebral organisation under hypnosis. Bilateral electrodermal activity was examined to tones presented simultaneously with the induction of hypnosis. Susceptibility was monitored throughout. Two control conditions were devised, one for division of attention and another for relaxation. In addition there was a familiarisation session which permitted groups to be equated for rates of habituation. Both faster and slower habituation were found under hypnosis but the direction of change related to susceptibility; Susceptible subjects showed a reduction in orienting responses and Unsusceptible subjects an increase in responses. Susceptible subjects also had lower tonic levels of activity and fewer nonspecific responses during the induction prior to the tones. Neither relaxation nor listening to a story altered habituation systematically. Under hypnosis there was a reversal in lateral asymmetries in orienting response amplitudes in Susceptible subjects suggesting a shift in hemispheric influences from left to right.

Adult↗
PubMed1979

Influence of D-or DL-propranolol and chlorpromazine on habituation of phasic electrodermal responses in schizophrenia.

Propranolol was found to share the properties of the racemate in facilitating habituation of the electrodermal orienting reflex in schizophrenic patients. This effect appeared independent of influences on levels of skin conductance and non-specific responses. Chlorpromazine did not normalise orienting activity. If the findings from open clinical studies that D-propranolol has anti-psychotic properties are confirmed, the fact that dextro propranolol has only minimal cardiovascular effects may give it important advantages as an anti-psychotic agent. Controlled clinical studies to prove its therapeutic action and neurobiological studies to determine its central mechanisms of action are warranted.

Adolescent↗
PubMed1979

Gains, losses and lateral differences in the hearing of schizophrenic patients.

Schizophrenic patients, whether newly admitted to hospital or institutionalized, exhibited ear differences in absolute threshold. Right ear thresholds were superior to left ear thresholds especially at frequencies above 2 kHz, but deteriorated in the course of the day or as a result of repeated testing. These effects were attributed to the dynamics of left hemisphere processes which in schizophrenia appear susceptible to inhibition and fatigue, effects that may be endocrine related. Relative to control subjects institutionalized schizophrenic patients showed superior hearing below 1 kHz and inferior hearing above 2 kHz.

Adult↗
PubMed1977

Propranolol as an adjunct to the treatment of schizophrenia.

Propranolol contributed usefully to the practical management of patients with chronic schizophrenia whose florid symptoms had not remitted with major tranquillisers. 14 patients who had received an average equivalent of 954 mg per day of chlorpromazine for 10 years were given, in addition, either propranolol or a placebo for 12 weeks. Both groups had improved by the twelfth week, but the propranolol group had improved significantly more.

Adult↗
PubMed1976

Clinical attributes of schizophrenic skin conductance responders and non-responders.

Nurses rated schizophrenics, subclassified upon the basis of the presence or absence of electrodermal orienting responses, with Wittenborn scales. Amongst non-institutionalized patients responders, who are more highly aroused psychophysiologically than non-responders, were more manic, anxious, assaultive and attention-demanding. Amongst institutionalized patients skin conductance levels and spontaneous fluctuations were associated with behaviour of a schizophrenic character.

Adult↗