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Biomedical subjects

J Gruzelier

Publications and source records attributed to J Gruzelier.

At least 37 records · Page 2Linked to original sources
PubMed1995

Social and physical anhedonia in relation to cerebral laterality and electrodermal habituation in unmedicated psychotic patients.

The neglect of psychophysiological investigation of social anhedonia, in contrast to physical anhedonia, was addressed by examining relations between electrodermal orienting responses and their lateral asymmetry in unmedicated schizophrenic, bipolar/schizoaffective, and unipolar depressive patients and normal control subjects. In support of relations between social withdrawal and right-hemispheric reactivity, social anhedonia was associated with a predominance of right-hemispheric influences in schizophrenic and bipolar/schizoaffective patients but not in depressive patients. Anhedonia in all but the depressive group was also related to responsiveness, particularly when fast habituators were pooled with nonresponders and compared with moderate and slow habituators. Anhedonia was higher in the more responsive group. This was particularly true of physical anhedonia. The results support associations between both types of anhedonia--social and physical--and psychophysiology, and they also suggest that anhedonia is not a unitary concept.

Acoustic Stimulation↗
PubMed1995

Patterns of cognitive asymmetry and syndromes of schizotypal personality.

The Schizotypal Personality Questionnaire, modeled on the nine components of DSM-III-R schizotypy, was administered to 122 medical students along with the Thayer Activation-Deactivation Adjective Checklist and the Warrington Recognition Memory Test for words and faces. Close affinities were found between a three-factor schizotypal personality structure and a three-syndrome model of schizophrenia. Different patterns of cognitive asymmetry (word-face discrepancy scores) were related to Active and Withdrawn syndromes as in schizophrenia, and were related to high activation and general deactivation differences as predicted. A prospective single case study showed that a face-word discrepancy before a first episode of schizophrenia accurately predicted a Withdrawn presenting syndrome. The consistency between syndromes of schizophrenia and schizotypal personality in a normal population suggests possible etiological links between the two, and it supports a dimensional view of psychosis and subclinical predispositions.

Adult↗
PubMed1995

Neurophysiological evaluation of zidovudine in asymptomatic HIV-1 infection: a longitudinal placebo-controlled study.

The effect of early antiretroviral medication with zidovudine on neurophysiological functions was evaluated in subjects with asymptomatic HIV-1 infection. Patients were recruited participants of a larger double-blind randomised placebo-controlled treatment trial with zidovudine (Concorde). The main outcome measures included: quantitative electroencephalography (QEEG), auditory event-related potentials (AEP) and pattern-reversal visual evoked potentials (PRVEP), as well as standard clinical, virological and immunological markers. No significant impairment and no difference between treatment groups was found in visual P100 latency and auditory long-latency P3 responses which is in agreement with the absence of neurological and neuropsychological impairment over the study period. Significant treatment effects were revealed by quantitative electroencephalography (QEEG). While the placebo group showed a significant increase in delta and theta slow frequency QEEG activity over the study period, slow wave amplitude remained unchanged in the zidovudine group after a mean follow-up period of 28 months. In summary, the data provide evidence for a low level neuropathological process in asymptomatic HIV-1 infection which can be effectively suppressed by antiretroviral medication.

Adult↗
PubMed1995

Long-term zidovudine reduces neurocognitive deficits in HIV-1 infection.

OBJECTIVE: To determine the efficacy of zidovudine (ZDV) in preventing decline of neurocognitive functions in HIV-1 infection. DESIGN: Retrospective evaluation of subjects enrolled in a natural history study. Two analyses were made to evaluate the effect of (1) current ZDV, irrespective of length of treatment and (2) long-term ZDV treatment for at least 1 year. SETTING: Subjects were recruited from HIV out-patient clinics. PATIENTS: HIV-1-seropositive subjects were assigned to one of three groups according to the Centers for Disease Control and Prevention classification: asymptomatic infection (n = 60), symptomatic infection but without AIDS (n = 51), and AIDS (n = 32). MAIN OUTCOME MEASURES: Standardized neuropsychological and neurophysiological measures [electroencephalogram (EEG) and long-latency evoked potentials]. RESULTS: Long-term ZDV use was associated with improved cognitive performance in subjects with early symptomatic HIV-1 infection and AIDS, compared to subjects in the same clinical stage but without previous ZDV treatment. This was corroborated by neurophysiological evidence of reduced slow-wave EEG amplitude in the ZDV-treated subjects. The advantage of ZDV treatment was evident despite lower immune status in most treated subjects. CONCLUSIONS: The findings in this natural history study indicate that long-term ZDV treatment may be an effective prophylactic to reduce neurocognitive deficits in symptomatic HIV-1 infection, thereby lowering the risk for developing HIV-1-associated dementia.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Patterns of cognitive asymmetry and psychosis proneness.

We previously reported evidence in university students of three syndromes of schizotypy which have strong affinities with three-syndrome models of schizophrenia. As in schizophrenia two of the syndromes were associated with opposite hemispheric asymmetry patterns: an Active syndrome with a left > right asymmetry, and a Withdrawn syndrome with a right > left asymmetry. The third Unreality syndrome bore no consistent relation to pattern of asymmetry. Cognitive asymmetry was measured by comparing recognition memory for words with memory for unfamiliar faces using a neuropsychological test which assesses temporoparietal functions. Here the same approach was extended to the broader concept of psychosis proneness with a new inventory with four subscales: Introvertive Anhedonia, Impulsive Nonconformity. Unusual Experiences, and Cognitive Disorganisation. In support of the relevance of an activation dimension to cognitive asymmetry, Impulsive Nonconformity was associated with word > face superiority, as was a self report measure of Energy. Introvertive Anhedonia was associated with face > word superiority. As in schizophrenia these predicted asymmetry relations were significant in males only. Neither the Unusual Experiences nor Cognitive Disorganisation subscales were associated with cognitive asymmetry.

Adult↗
PubMed1994

Visual processing, lateralization and syndromes of schizotypy.

There is an association between positive features of schizotypy and dyslexia, largely involving distortions of visual and auditory perception and associated cognitive anomalies. In dyslexia, there is strong evidence for a disorder of subcortical magnocellular pathways, which may underlie these perceptual aberrations. Here we investigated visual processing in relation to three syndromes of schizotypy-Active, Withdrawn and Unreality-in normal adults, using a "dot localization" test of visual direction sense on which dyslexics perform poorly, and which should be sensitive to magnocellular dysfunction. Results showed that increased error scores were associated with both the positive syndromes, Active and Unreality, which in this study were highly correlated. There were also interactions between each syndrome and the direction of errors, such that high scorers on the Unreality and Active syndromes made more errors on leftward trials, while high Withdrawn subjects made fewer left and more right errors. Mixed handers also showed poorer performance than consistent handers. The evidence of poor visual direction sense in relation to positive syndromes of schizotypy and mixed handedness is consistent with the previous results for dyslexics, who also show these features. The opposite lateralization of errors in the positive v negative syndromes of schizotypy is in keeping with the model of hemisphere imbalance and patterns of cognitive asymmetry which distinguish Active from Withdrawn syndromes. These results are considered in relation to the proposal that a disorder of magnocellular function may underlie the perceptual distortions which are common to dyslexia and positive syndromes of schizotypy.

Adolescent↗
PubMed1994

Bilateral electrodermal activity and cerebral mechanisms in syndromes of schizophrenia and the schizotypal personality.

Bilateral electrodermal measurement was among the first to investigate abnormalities of lateralization in schizophrenia, and recent classification of non-institutionalized patients by lateral asymmetry has delineated positive and negative syndromes associated with opposite states of hemispheric balance. The neuropsychology of the symptoms is consistent with higher left- than right-hemispheric activity in the positive syndrome, and higher right- than left-hemispheric activity in the negative syndrome, evidence which in turn is consistent with current theory about hemispheric influences on electrodermal responses. As all patients had Schneiderian symptoms in common this provided a three-syndrome model, a model having affinities with contemporary reports of three-factor solutions in factor analyses of clinical ratings. All approaches describe two positive syndromes and one negative syndrome. The same model applied to the schizotypal personality has produced a three-factor solution having a strong bearing on the three schizophrenia syndromes, together with evidence of imbalances in functional lateralization that are consistent with the schizophrenia model. It is proposed that the controversy surrounding the orienting and habituation anomalies in schizotypal personality, which include reduced activity, augmented activity, and irregular habituation, may be elucidated by examining relationships with the three-syndrome model and through bilateral measurement. However, provision must be made for distinctions between processes of fixed structure and dynamic function, a critical requirement in view of the relations between electrodermal reactivity and orienting to the dynamic processes of arousal, attention and anxiety. The central nervous system underpinnings of electrodermal responsiveness in schizophrenia, notably the responder-non-responder distinction, is beginning to be elucidated through neuropsychological testing and brain imaging techniques. Research is warranted to explore an integration between the syndromes which evolved from bilateral measurement, and the responder-non-responder classification which arose from considerations of limbic dysfunction.

Brain↗
PubMed1994

A controlled investigation of right hemispheric processing enhancement after restricted environmental stimulation (REST) with floatation.

Two groups of 16 subjects, 8 of each gender, were examined on two occasions, one group before and after restricted environmental stimulation with floatation, and the other group without floatation was the control group. They were examined with a tactile object discrimination task carried out with each hand separately while blindfolded, and with a recognition memory test for words and unfamiliar faces, a test validated on neurological patients with left and right hemispheric lesions respectively. Consistent with both tasks the floatation group showed a significantly greater enhancement of right hemispheric processing after floatation than was found when retesting the controls. The results were distinguished from previous research on hypnosis where the same relative state of hemispheric imbalance was achieved with the same tasks, but largely through inhibitory influences on the left hemisphere.

Adult↗
PubMed1994

A longitudinal study of the neuropsychiatric consequences of HIV-1 infection in gay men. I. Neuropsychological performance and neurological status at baseline and at 12-month follow-up.

The aim of this study was to determine whether HIV infection is associated with neurological or neuropsychological impairment in the asymptomatic and early symptomatic stages of disease. Subjects included 61 gay men (41 HIV-, 20 HIV+) who were assessed at the time of requesting their first HIV test and again 12 months later. The assessments at baseline were conducted double-blind to HIV serostatus. Measures included a neuropsychological battery, neurological examination and full psychiatric assessment. There were no differences between the asymptomatic HIV+ and HIV- groups at baseline or at follow-up in terms of mean scores on neuropsychological tests. Mean scores were within the normal range for all neuropsychological tests for both groups. Multiple regression analysis was used to predict each individual's performance at follow-up on the basis of their baseline performance, psychiatric state, neurological history and drug use for each of the neuropsychological tests. HIV+ subjects were more likely than control subjects to perform at a significantly lower level at follow-up on one or more tests than predicted on the basis of their baseline performance.

AIDS Dementia Complex↗
PubMed1994

A longitudinal study of the neuropsychiatric consequences of HIV-1 infection in gay men. II. Psychological and health status at baseline and at 12-month follow-up.

The aim of this study was to determine whether HIV infection is associated with increased psychosocial distress in the asymptomatic and early symptomatic stages of disease and to determine the factors associated with reporting health symptoms. Subjects included 61 gay men (41 HIV--, 20 HIV+) who were assessed at the time of requesting their first HIV test and again 12 months later. Measures included a detailed standardized psychiatric interview (Present State Examination, PSE), a range of psychosocial self-report measures and a physical symptom checklist. There were no differences between the HIV+ and HIV-- groups in terms of self-reported symptoms. Multiple regression analysis showed that the symptom reporting was not associated with clinical or immunological markers of disease progression but was associated with measures of psychosocial distress. Although both groups showed elevated levels of psychosocial distress at the time of HIV testing, there were no differences between serostatus groups at follow-up. Multiple regression analysis indicated that the best predictors of PSE scores at follow-up were baseline PSE score and a history of psychiatric illness. Early HIV disease is not associated with increased psychosocial distress and symptom reporting is more closely related to psychological measures than to clinical or immunological markers of disease.

AIDS Dementia Complex↗
PubMed1993

Localisation of cerebral function using topographical mapping of EEG: a preliminary validation study.

In an attempt to validate the use of topographical mapping of EEG as a method of localising cerebral function, EEG was recorded during a simple motor task. A minimum of 20 sec artifact-free EEG was recorded from 24 healthy right handed subjects in each of 4 conditions: eyes open 1, motor task (left/right, order randomized), eyes open 2. EEG amplitude maps were computed in delta, theta, alpha, and beta (1 and 2). Differences were seen between the eyes open and the motor conditions in alpha, beta 1 and beta 2 localised to the motor and supplementary motor areas. It is argued that topographical mapping of EEG is a valid method of localising cognitive function in healthy individuals for the Luria task.

Adult↗
PubMed1993

Individual reliability of amplitude distribution in topographical mapping of EEG.

Whilst there is an accumulation of evidence suggesting that many quantitative EEG parameters show good stability and reliability, no previous study has considered whether the spatial distribution of EEG amplitude is reliable over time within a session. This study reports on the spatio-temporal reliability of EEG using data recorded from 24 subjects in a baseline condition with eyes open and also whilst performing a simple motor task. Both the internal stability and test-retest reliability for electrode parameters were comparable to previously published data. For most individuals, amplitude distribution was stable within each recording condition, but the test-retest reliability after 40 min was less good with the poorest reliability in the delta frequency band. Most subjects showed spatio-temporal reliability of less than 0.7 in at least one frequency band. In contrast, spatio-temporal reliability for the group average was good and exceeded 0.88 in all frequency bands. It is argued that the results indicate that reliability is insufficient to allow topographical comparisons for a single individual, but is more than adequate to allow group comparisons.

Adolescent↗
PubMed1993

Bilateral auditory-evoked potentials in conditions of hypnosis and focused attention.

Brain event-related potentials (ERPs) evoked by auditory stimulation were used to study cerebral hemispheric activity during hypnosis. ERPs were recorded from bilateral central (C3 and C4) and temporal (T3 and T4) scalp locations in response to tone pips in 6 medium-high and 6 low-susceptible subjects in three conditions: baseline (tones only), hypnosis (tones plus hypnotic induction), and a focused attention control (tones plus a newspaper story read by the hypnotist). Task asymmetries were individually adjusted for baseline asymmetries. Responses from central locations did not differentiate hypnosis from focused attention for either group. The same was true of temporal locations for the low-susceptible group. The predominant temporal lobe pattern for both conditions and groups was larger left than right responses. The exception was the hypnosis condition for the medium-high susceptible group where there was an increase in responses in the right temporal lobe.

Acoustic Stimulation↗
PubMed1993

Neuropsychological evidence of reductions on left frontal tests with hypnosis.

Individuals with high and low susceptibility to hypnosis were compared in a baseline condition and after instructions of hypnosis on tests of anterior left and right hemispheric functions--word fluency to letter categories, word fluency to semantic categories, design fluency and bilateral finger tapping dexterity. With hypnosis high susceptibles showed a reduction in word generation to letter categories, no significant change in word generation to semantic categories, an improvement in design fluency, and bilateral reductions in finger tapping dexterity. Low susceptibles showed the opposite changes except for the improvement in design fluency. These results, together with correlational results, were interpreted as evidence of central inhibitory processes, particularly of the left hemisphere, in response to instructions of hypnosis in high susceptibles.

Adult↗
PubMed1993

Cerebral asymmetry and hypnosis: a signal-detection analysis of divided visual field stimulation.

Brightness discriminations in a divided-field paradigm were examined with a signal-detection procedure in three sessions, the second with hypnosis. Practiced, hypnotically susceptible Ss were subdivided into high- (n = 6) and medium- (n = 5) susceptible groups on the basis of a susceptibility scale monitored throughout the hypnosis session. High-susceptible Ss showed increases in d' in the left visual field (right hemisphere) with hypnosis, whereas medium-susceptible Ss showed bilateral enhancements. Beta remained invariant in both groups across three sessions but was higher in the left visual field. The results provide evidence of altered brain function with hypnosis and an association of focal right hemispheric changes with high susceptibility and, through the invariance of beta, fail to support the attribution of perceptual changes to attitudinal, nonstate factors.

Adult↗
PubMed1991

Stress induced reversal of a lexical divided visual-field asymmetry accompanied by retarded electrodermal habituation.

An interplay of structural and dynamic process cerebral asymmetries was investigated with medical students in a within subject design. Structural asymmetries were investigated with a divided visual-field lexical task and dynamic asymmetries through the influence of anxiety induced by examination stress and compared with a less stressful occasion. The validity of the stressful life event was substantiated by measures of non-specific electrodermal responses and a frustration-tension subscale from an anxiety questionnaire. The order of testing was counterbalanced. Under stress there was a shift in hemispheric balance such that a right visual-field advantage gave way to a left visual-field advantage. Variations in hemispheric processing were more pronounced in the right hemisphere in which performance was enhanced under stress.

Adult↗
PubMed1990

Topographical EEG differences between schizophrenic patients and controls during neuropsychological functional activation.

Ten DSM III schizophrenic patients belonging to an Active syndrome were compared with 10 age- and sex-matched normal controls on neuropsychological tests with concurrent monitoring of topographical EEG using a brain imager with a 28-electrode array. In line with predictions, abnormalities in patients were found in tests involving right hemispheric functions. Deficits were found in recognition memory for faces as distinct from a verbal recognition memory task. Right temporo-parietal involvement in the faces task was confirmed by an absence of beta II amplitude reduction in patients compared with controls in the right temporo-parietal region. A similar anomaly occurred in patients in a left- but not right-hand finger-thumb apposition test in left anterior and right posterior regions, and also in a passive visual fixation task where it was located bilaterally in the occipito-parietal region. Functional activation with neuropsychological tests holds promise as one approach to the validation of topographical mapping of brain electrical activity.

Adult↗