This investigation was undertaken with a view in the first place to testing a claim of Pauline Davis as to the correlation, in manic-depressive psychosis, between certain psychological and electroencephalographic features, notably alpha frequency and irregular fast low voltage records which she termed "choppy". The scope undertaking is, however, wider in as much as we shall be testing correlations with rhythms other than the alpha, and not only in respect of frequency but also of amplitude and per cent time. Moreover the notion of "choppy" records will be subjected to critical analysis and replaced by a detailed characterization of irregular or organised records.

A "self-serving" attributional bias (attributing positive events to something about oneself, and negative events to external factors) commonly found in non-patients has been found to be exaggerated in patients with persecutory delusions. Moreover, research using a newly developed attribution measure, the Internal, Personal and Situational Attributions Questionnaire (IPSAQ; 1996), found that paranoid patients tended to exhibit a "personalizing bias" for negative events, choosing external attributions that located blame in others. Such attributional biases have been found in relation to self-referent events but it is unclear whether they are also found in relation to other-referent events. The present study investigated whether participants made differential attributions, depending on whether hypothetical events were happening to themselves or to another person. The IPSAQ was modified to incorporate another dimension: self- versus other-referent events. The modification was piloted on 21 non-patients and some additional alterations made. There is also debate about the relationship between self-esteem and depression in people with persecutory delusions. Consequently, this was also explored in the study. In the main study, there were 62 participants (20 patients with persecutory delusions, 21 depressed patients, 21 non-patients). Findings indicated acceptable test-retest and internal reliability for the IPSAQ-M. For self-referent events, paranoid participants made more external-personal attributions for negative events than depressed participants (but not non-patients). Depressed participants exhibited an abnormal attributional style. Paranoid participants did not exhibit an exaggerated self-serving bias or a personalizing bias. For other referent events, depressed patients made causal attributions similar to nonpatients. A difference in attributions, between self- and other-referent events, was less clear for paranoid participants. In addition, significant negative correlations were found between self-esteem and depression for all three groups, supporting a "normal emotional processes' account of persecutory delusions. Implications for psychological treatment and possible avenues for future research were discussed, as well as methodological and theoretical limitations of this study.

This research examines recent developments in the cognitive model of auditory hallucinations ("voices") in people with psychoses. Following the research of Chadwick and Birchwood (1994), data are presented on the behavioural, cognitive and affective responses to persistent voices of thirty participants with psychoses. After testing the reliability of their interview, data is then compared to that of the Chadwick and Birchwood (1994) sample. In addition, the research aimed to develop the cognitive model of the emotional impact of voices by examining further possible associations with participants' self-evaluations, hypothesising that these evaluations are associated with the affective response. The cognitive assessment of voices shows reasonable inter-rater and test re-test reliability. Compared to the Chadwick and Birchwood (1994) sample, the present sample had a greater proportion of negative affective responses to voices. regardless of their beliefs about the voices' benevolence or malevolence. Participants in this sample were less likely to endorse the voices' omnipotence or omniscience. Similarities were shown in behavioural responses and factors reported as proof of the voices' potential power. Although it was not possible to explore the associations between the content of voices, affective responses, self-evaluations and distress due to a preponderance of negative affective responses in this sample, nevertheless, it was possible to describe these responses. Participants in this sample had a predominantly negative content to their voices. Those who were able to access a personal meaning were found to have, predominantly, negative personal meanings, low self esteem and moderate distress as measured by standardised instruments.

ABSTRACT BACKGROUND: Disconnections in cortical-related networks, the neuronal circuits of higher-order brain operations (attention, cognition, memory and perception), are thought to underlie dysfunctions of conscious integration such as those seen in schizophrenia. More than 80% of the neurons that make up these complex systems are glutamatergic. Clinical and experimental evidence suggest that NMDA-type glutamate receptors are implicated in the pathophysiology of schizophrenia. Cognitive impairment and schizophrenia-like symptoms (hallucinations and psychosis) are produced in humans by the administration of a single subanaesthetic dose of ketamine, a non-competitive NMDAr antagonist like phencyclidine and MK-801. The neuronal mechanisms underlying transient disruption in NMDAr function remains unknown. / Disorders of cognition-related coherences of gamma frequency (30-80 Hz) oscillations between cortical areas are a major functional abnormality in schizophrenic patients. Ketamine and MK-801, non-competitive NMDA receptor antagonists, abnormally and dose-dependently increase the power of wake-related, spontaneously occurring gamma oscillations in the electro-encephalogram (EEG) of the rat neocortex and concomitantly induces abnormal behaviour relevant to schizophrenia, including hyperlocomotion and ataxia. This observation is consistent with findings obtained in humans supporting the hypothesis that pathological (abnormal increased synchronization in) gamma oscillations are correlated with psychotic symptoms. / Schizophrenia-like psychosis of epilepsy (interictal psychosis) occurs in 3%–7% of patients with epilepsy including those with generalized non-convulsive absence epilepsy. Patients with generalised epilepsy have been reported to have an increased the power of their gamma frequency activity on the EEG. Ketamine and MK-801 also dose-dependently suppress SWD and concomitantly induces hyperlocomotion in WAG/Rij rats, genetic rat model of absence epilepsy. Thus, the study also investigated gamma oscillations in Genetic Absence Epilepsy Rats from Strasbourg (GAERS), and the effect of NMDA receptor antagonists. / METHODS: The relationship between quantitative measures of gamma power and locomotion was assessed in 8 freely moving rats following single injections of ketamine (<5 mg/kg) or MK-801 (<0.16 mg/kg). The impact of these NMDAr antagonists on neocortical gamma oscillations was also investigated in 24 anesthetized rats, including control experiments with substances that modulate dopaminergic neurotransmission. The second part of this study investigated the relationship between the spontaneously occurring gamma oscillations in the electrocorticogram of the neocortex and the quantitative measures of locomotor activity in eight freely moving non-epileptic control (NEC) rats and seven Genetic Absence Epilepsy Rats from Strasbourg (GAERS) before and after subcutaneous administration of a single dose of ketamine (<5.0 mg/kg), MK-801 (<0.16 mg/kg) or vehicle (sodium chloride, .9%). / RESULTS: NMDAr antagonists, ketamine and MK-801 were found to both induce highly correlated dose dependant hyperlocomotion and aberrant gamma oscillations, with the time course of this more prolonged in following MK-801. Ketamine and MK-801 also induced significant increase in the gamma power in deep urethane anaesthetized and neuroleptanagesized rats, and slight increase in the gamma power in pentobarbital anaesthetized rats. In the second part of the study the power of spontaneously occurring electroencephalic gamma frequency oscillations were demonstrated to be significantly increased (twofold) in GAERS compared to their non-epileptic counterparts (NEC). At the onset of the epileptiform spike-and-wave discharges (seizures) there was a dramatic increase (seven to nine fold) compared to interictal gamma power. The administration of the NMDAr antagonists induced dose-dependent highly correlated aberrant interictal gamma oscillations and hyperlocomotion in GAERS similar to that seen in the non-epileptic rates except that peak and total locomotor responses were siginificantely decreased in GAERS following ketamine administration and that GAERS had a later peak in gamma power and in hyperlocomotion compared to NEC rats following MK-801 administration. / CONCLUSIONS: The present study demonstrated that ketamine and MK-801 dose-dependently induced highly correlated hyperlocomotion and aberrant gamma oscillations in non-epileptic control rats, suggesting that abnormal increased synchronization in ongoing gamma oscillations in cortical-related networks might cause dysfunctions of conscious integration, as seen in patients with schizophrenia. The study also demonstrated that ketamine- and MK-801-induced gamma hyperactivity is not caused by ataxic behavior and hyperlocomotion and is independent on conscious sensorimotor processing. Ketamine and MK-801 also induced similar changes in gamma power in rats with geneticly epileptic rats (GAERS), however this occurred of a baseline of approximately double the gamma power of the non-epileptic rats. This later finding suggests that gamma suggests that frequency oscillations might have a role in process of epileptogenesis. Overall the study results support the exciting possibility that aberrant gamma oscillations are a promising potential endophenotype for schizophrenia and epilepsy that could be used in the development of novel therapies for these two complex brain disorders.

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