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Biomedical subjects

J Gruzelier

Publications and source records attributed to J Gruzelier.

At least 19 recordsLinked 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 Different patterns of cognitive asymmetry (word-face discrepancy scores) were related to Active and Withdrawn syndromes as in schizophrenia, and were related to high activation and general deactivation differences as predicted.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single case study showed that a face-word discrepancy before a first episode of schizophrenia accurately predicted a Withdrawn presenting syndrome.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

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

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↗
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↗
PubMed1990

Psychological and psychophysiological characteristics in irritable bowel syndrome.

Psychiatric disorder is reported to occur in a large proportion of patients with irritable bowel syndrome (IBS) and psychological treatment methods have been advocated for this patient group. In a sample of 25 out-patients with intractable IBS, only four patients with psychiatric disorder were identified. The majority did not have elevated levels of anxiety or depression nor was there evidence of significant abnormal illness behaviour. Electrodermal activity did not show the extremes of responding and habituation associated with anxiety, depression or chronic pain. It is suggested that, when accurate diagnostic criteria are employed, a specific relationship between IBS and psychopathology is no longer evident.

Adult↗
PubMed1989

Electrodermally differentiated subgroups of anxiety patients and controls. II: Relationships with auditory, somatosensory and pain thresholds, agoraphobic fear, depression and cerebral laterality.

Patients diagnosed (DSM III) with anxiety disorders (agoraphobia, panic syndrome, generalised anxiety syndrome) were classified along with controls as electrodermally stabile or labile on the basis of non-specific electrodermal activity and rate of habituation to tones. While patients showed more evidence of psychopathology than controls on scales of anxiety, neuroticism, depression and agoraphobic fear, patient labiles scored higher than stabiles on agoraphobic fear and were differentiated by higher scores of Beck depression. They were also more sensitive to pain, whereas patient stabiles were less sensitive at absolute somatosensory threshold. Amongst controls agoraphobic fear was associated with lability and stabiles scored higher on autonomy in locus of control. Lateral asymmetries in auditory thresholds were consistent with reciprocal hemispheric influences on electrodermal reactivity and habituation, modifiable by anxiety. Interrelationships between fear, depression, sensitivity to somatosensory stimulation, pain, and superior vigilance performance in patient labiles were consistent with elevated right hemisphere function.

Agoraphobia↗
PubMed1988

Impairments on neuropsychologic tests of temporohippocampal and frontohippocampal functions and word fluency in remitting schizophrenia and affective disorders.

Experimental neuropsychologic tests were administered to acute patients with schizophrenia and affective psychosis and to normal controls. Patients had remitting illnesses. Tests included memory for recurring digit and block spans (left and right temporohippocampal), digit and block spans (lateralized parietal/frontal), spatial and nonspatial conditional associate learning (frontohippocampal), and oral word fluency to letter-designated categories (frontal) and semantic-designated categories (left-sided). In 81% of schizophrenic patients patterned deficits incompatible with generalized losses of function were disclosed. Patterns were heterogeneous and characterized by (1) the frequency and severity of left temporohippocampal impairment; (2) asymmetric frontohippocampal function such that severity of bilateral impairment was associated with poorer nonspatial learning and superior performance with better nonspatial learning; (3) syndrome relationships predicted by the hemisphere imbalance syndrome model pertaining to positive and negative symptoms and the catatonic syndrome; (4) a generalized deficit independent of temporohippocampal functions; and (5) no relationship between performance and computed tomographic signs or medication. Patients with affective disorders had patterned deficits characterized by bilateral impairments that disclosed a preponderance of deficits in spatial learning and memory; depressives demonstrated impairments in digit span.

Affective Disorders, Psychotic↗
PubMed1988

The use of bilateral skin conductance measurement in elucidating stimulus versus response processing influences on the orienting reaction.

In three experiments the importance of behavioural consequences as a determinant of the amplitude of the electrodermal response is demonstrated. Bilateral skin conductance responses were examined to same-different stimuli consisting of moderate intensity tones differing in pitch (S1, S2), to a response cue to make a unimanual button-press if the stimulation were judged the same (S3), and to feedback (S4). In the first two experiments in which a right-hand action was required, responses were larger to S2 than S1 on 'response', compared with 'no-response' trials. This was replicated in the second experiment where the same effect was also found to S3. In the third experiment the hand performing the action was varied; the influence of stimulus consequences on responses to S2 was replicated when the right hand performed the action; when the left hand was involved elevated responses to S2 occurred, irrespective of the perceptual judgement. In all experiments responses tended to be larger on trials where a correct judgement was made. The use of bilateral recording with a unilateral behavioural response confirmed the influence of effector functions on electrodermal responses. Hemispheric influences were contralateral and excitatory. The results were discussed in terms of multiple central determinants on electrodermal responses, the influence of cerebral laterality, and of sympathetic-somatic coupling.

Adult↗
PubMed1988

A psychophysiological differentiation between hypnotic behaviour and simulation.

Psychophysiological differentiation between conditions of hypnosis and simulation were examined with markers evolved from a series of experiments charting neuropsychophysiological accompaniments of hypnotic behaviour. Eighteen subjects participated in two sessions in which bilateral electrodermal activity was monitored to moderate intensity tones. Measurement in Session I, a Baseline-Control, of individual variation in rates of habituation of orienting responses, non-specific responses and tonic levels of skin conductance, enabled allocation of matched groups to Session II in which the same auditory stimuli were mixed with a taped hypnotic induction. Half the subjects were instructed to fake hypnosis and the others to comply. In session II the groups were differentiated as follows: (1) rate of habituation to the tones was retarded in the simulation condition and facilitated in the hypnosis condition compared with baseline; (2) the incidence of non-specific electrodermal responses was elevated in simulators after instructions to 'fake hypnosis'; (3) right-hand levels of skin conductance were elevated in simulators; (4) all but one subject in the hypnosis condition admitted to hearing the tones whereas all but one in the simulation condition claimed not to have heard them.

Adolescent↗
PubMed1987

Rate of habituation of electrodermal orienting responses: a comparison of instructions to stop responding, count stimuli, or relax and remain indifferent.

Thirty-nine subjects listened to two series of repetitive tones, the second series of which was of higher or lower pitch and of higher intensity. Before the first series all subjects were given conventional instructions to relax and adopt a passive attitude to the tones. Before the second tone series one of three instructions was given: to maintain a relaxed and passive attitude, to inhibit responding, to count the stimuli silently. The three groups showed roughly equivalent rates of habituation to the first tones series but the group instructed to count the tones showed slower habituation than the groups instructed to remain indifferent or to inhibit responses. A recommendation to clarify task demands in habituation experiments, by informing subjects that the aim was to see how quickly subjects stopped responding, showed no advantages over conventional instructions.

Adult↗