The arousal hypothesis of schizophrenia: current status.
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Autonomic Nervous System↗
Biomedical subjects
D J Done
Publications and source records attributed to D J Done.
Automatic and strategic volitional saccadic eye movements in psychotic patients.
Drug-free schizophrenics were compared with depressive psychotics and normal controls on two saccade initiation tasks which differed with respect to the type of stimulus that initiated a saccadic response. Strategic initiation (SIS) appears to use a route different from that in automatic initiation (AIS). The SIS task revealed slowed responding in psychiatrically ill patients if their cognition was impaired, but all groups responded similarly on the AIS task. Schizophrenics could be separated from depressed psychotics by their inability to utilize temporal redundancy to speed up saccade initiation on the SIS task. Neurophysiological evidence implicates specific impairments in the frontal eye field (FEF) and/or basal ganglia.
Depressive Disorder↗
Experiences of alien control in schizophrenia reflect a disorder in the central monitoring of action.
Twenty-three acute psychotic patients who were drug free at the time of testing performed a motor task designed to elicit many errors. Normal subjects and many of the psychotic patients were able to correct these errors in the absence of visual feedback. The ability to make such corrections depends on the subject knowing what response he has just made. Patients with experiences of alien control of their thoughts and actions who formed a subgroup of those classified as schizophrenic, were significantly less likely to make error corrections in the absence of visual feedback. This result is consistent with our previous suggestion (Frith, 1987) that these symptoms are a consequence of problems with the central monitoring of responses.
Affective Disorders, Psychotic↗
Towards a neuropsychology of schizophrenia.
A viable neuropsychology of schizophrenia requires, first, that signs and symptoms be understood in terms of underlying psychological processes and, second, that these underlying processes be related to brain systems. We propose that the negative signs of schizophrenia reflect a defect in the initiation of spontaneous action, while the positive symptoms reflect a defect in the internal monitoring of action. The spontaneous initiation of action depends upon brain systems linking the prefrontal cortex and the basal ganglia. Internal monitoring, carried out in the hippocampus, of spontaneous action, depends upon links between the prefrontal cortex and the hippocampus via the parahippocampal cortex and the cingulate cortex.
Brain↗
Routes to action in reaction time tasks.
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Choice Behavior↗
Age of onset of schizophrenia in siblings: a test of the contagion hypothesis.
The possibility that schizophrenia is horizontally transmitted has been assessed in an analysis of age of onset in 264 recorded pairs of siblings with the disease. Age of onset was found to be correlated between siblings, and there was a tendency for the disease to occur at an earlier age in the younger sibling. Three explanations for this finding are considered: horizontal transmission, early detection, and ascertainment bias. An analysis by date of birth differences between siblings gives results consistent with horizontal transmission, but analysis by order of onset of illness (which shows that the age shift is not seen in elder-sibling-ill-first pairs) indicates that ascertainment bias (which arises from a tendency to include an excess of early onsets in younger siblings) is a more cogent explanation of the age shift. Although horizontal transmission is not altogether eliminated, the data suggest that age of onset is determined by genetic or prenatal factors rather than environmental precipitants in postnatal life. The retrovirus/transposon hypothesis (Crow, 1984) can accommodate the findings more readily than the gene-virus interaction hypothesis (Crow, 1983).
Adolescent↗
Reducing persistent auditory hallucinations by wearing an ear-plug.
A case study is presented of the effects of wearing an ear-plug in a single patient with persistent auditory hallucinations. Beneficial effects were detected when the plug was in the dominant ear only.
Adult↗
A longitudinal study of the development of visual field advantage for letter matching.
The visual field advantage for letter matching was investigated longitudinally from 5 to 7 yr. A right visual advantage was found with very little indication of any increase with age. Cross-sectional controls exhibited somewhat less of a right visual field advantage. In a group of 4-yr-olds who could not name letters a left visual field advantage was observed for boys. It is suggested that the right visual field advantage for visual-verbal material occurs from a mapping on to an already existing left hemisphere language system.
Child↗
The effect of context during word perception in schizophrenic patients.
Hospitalized chronic and acute schizophrenics were compared with age- and social-status-matched controls on word perception tests to measure the effect of context on recognition thresholds. In Experiment 1 the method of J. Morton (1964, British Journal of Psychology, 55, 165-180) was adopted to see how related and unrelated contexts influenced word recognition thresholds when both context and stimulus word were presented visually. Experiment 2 was an auditory analog of Experiment 1 and in addition the chronic schizophrenics were selected on the basis of a presence or absence of auditory hallucinations. The influence of context on perceptual thresholds was quite normal in all schizophrenics. However, analysis of the incorrect responses elicited showed that some schizophrenic subjects do produce bizarre or irrelevant responses or perseveration to a greater extent than their controls. These results are explained in terms of automatic and strategic modes of information processing. The automatic processes responsible for the adjustment of perceptual thresholds operate normally in schizophrenics but response production which demands strategic selection and editing of responses is prone to malfunction which results in the observed deviations in the normal use of language.
Adult↗
Stereotyped responding by schizophrenic patients on a two-choice guessing task.
On each of a sequence of trials subjects had to guess whether a cross would appear on the left or the right side of a computer screen. The sequence of cross positions was random. Normal controls, manic-depressive patients and patients with senile dementia produced relatively random sequences of responses, as did acute schizophrenic patients with positive symptoms. Acute schizophrenic patients with negative symptoms and chronic patients produced more stereotyped sequences with many response alternations (LRLR). Chronic schizophrenic patients with negative symptoms and intellectual deterioration (defect state) produced very stereotyped sequences with many preservations (LLLL). This severe restriction of response sequences is similar to that shown by animals after treatment with amphetamine. It is suggested that it is due to an impairment of a higher order control process which normally inhibits the repetition of sequences of behaviour when these have proved inappropriate.
Adolescent↗
Stimulus integration in schizophrenia.
Twenty-four chronic institutionalized schizophrenics and 11 acute non-institutionalized schizophrenics were compared with 20 controls (matched for age, sex and socio-economic status) on a task normally eliciting stimulus integration (Garner, 1974). The subjects had to classify the widths of a sequence of rectangles into one of four categories while ignoring their height. Each response was timed. Although all the patients performed the task more slowly than their appropriate control group, the results showed that schizophrenic patients integrated these simple stimuli just as do normal subjects. Thus failure of simple stimulus integration is not a feature of schizophrenia.
Acute Disease↗
Monaural ear advantages in simple and choice reaction time: artifacts and individual differences.
Previous studies are said to show that there are ear advantages, usually right-sided, for simple RT to monaural tones. It has been disputed whether these ear advantages are the same for choice RT. Latencies for each hand were measured using a bimanual response and no ear advantages were found for either simple or choice RT. Ipsilateral responses were not faster than contralateral responses. However, subjects show significant differences in ear advantage from each other. It is suggested that all ear advantages for monaural tones in RT studies result from lateral biases and compatability effects.
Adolescent↗
Investigating visual knowledge in dementia of the Alzheimer type (DAT): evidence for a structured organization.
Given that certain types of semantic dysfunction in DAT have been attributed to difficulties in accessing visual knowledge, the issues of integrity of access to, and format of storage, within the "visual store" are particularly important. In these experiments, we tested 10 DAT patients and matched controls on the reality decision and part-whole matching tasks. Visual knowledge was found to be significantly impaired in the DAT group. Moreover, DAT patients displayed disproportionate deficits in accessing visual knowledge of items from nonliving categories. Results are interpreted within a framework of differential hierarchical access to visual representations of perceptually similar and perceptually distinct categories of items.
Aged↗