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Biomedical subjects

H G Stampfer

Publications and source records attributed to H G Stampfer.

9 recordsLinked to original sources
PubMed1991

The prognosis of depression in old age.

The 12-month outcome of 103 elderly depressed patients treated by psychiatrists in Perth, Western Australia, was good in 32-47% of cases, depending upon the stringency of the outcome criteria used. A higher than expected mortality was found, especially in men. No clear association was found between 12-month outcome and a variety of clinical variables at index admission, including chronic physical illness, severity of depression, and severe life events during follow-up. As the statistical power of this and other studies is small, it would be unwise at present to draw definite conclusions about the role of possible risk factors in the prognosis of depressed elderly. Vigorous treatment of the depressive illness and adequate after-care are important.

Aged↗
PubMed1990

Inverse filter computation of the neural impulse giving rise to the auditory evoked potential.

An impulse response hypothesis for evoked potentials is tested. The auditory evoked potential (AEP) is shown to be the consequence of an impulse (the arrival of sensory signals in cortex) giving rise to an impulse response (the resonation of electrocortical activity in the form of group linear waves). To demonstrate this, pre- and post-stimulus EEG activity was recorded from subjects engaged in performance of an auditory odd-ball experiment. For each stimulus, the impulse required to account for the single auditory evoked potential (AEP) as a linear impulse response, was computed by use of the inverse of a filter obtained by autoregression analysis of the pre-stimulus EEG epoch. Single estimations of the impulse were then averaged. The average impulse exhibits a time course and topology consistent with the arrival of neural volleys in the cortex. The physical validity of the hypothesis is supported by a high lag correlation of the following values of the AEP to the average impulse. A further test calculation supports the linear additivity assumptions of the hypothesis.

Acoustic Stimulation↗
PubMed1990

"Negative symptoms": a cumulative trauma stress disorder?

A theory is proposed that "negative symptoms", which are usually associated with schizophrenia, are manifestations of a traumatic stress disorder that is fundamentally similar in terms of the clinical phenomena and pathophysiological disturbance to chronic post-traumatic stress disorder (PTSD) as defined in DSM-III-R. Wider theoretical implications are explored briefly.

Arousal↗
PubMed1989

A comparison of early-onset and late-onset depressive illness in the elderly.

Elderly patients with early-onset and late-onset depressive illness presenting to psychiatrists for treatment were compared for social, demographic, and clinical measures. For most factors measured no statistically significant differences were found. In the early-onset cases, patients were significantly more severely depressed. There was some evidence for the hypotheses that family history is less important and biological factors more important in late-onset depression. It is suggested that the latter hypothesis should be tested by a range of the newer neuroanatomical and neurophysiological laboratory investigations. The findings indicate that neuroticism is an important underlying factor in both early-onset and late-onset depression in the elderly.

Age Factors↗
PubMed1985

Important associations among EEG-dynamics, event-related potentials, short-term memory and learning.

Averaged and single sweep auditory event-related potentials (ERPs) were analysed in the time and frequency domain to demonstrate a dynamic, functional relationship between prestimulus EEG activity and poststimulus ERP changes. Evidence is presented of prestimulus "preparation changes" which were elicited by the presentation of regular, frequent target tones. The development of preparation changes was associated with prestimulus EEG synchronisation, frequency selective phase alignment at the point of stimulation and a greater predictability of the poststimulus response to target and nontarget tones. Time varying responses to target and nontarget tones are described for different experimental conditions and related to preparation rhythms. The mechanisms and possible neural correlates of the endogenous P300 change are discussed. The findings from this study and other relevant investigations have been used to formulate hypotheses about the relationships among preparation changes, ERPs and short-term memory, habituation and learning.

Adult↗
PubMed1985

Does frequency analysis lead to better understanding of human event related potentials.

A combined analysis procedure was used to study auditory, sensory evoked potentials (EPs) and event-related potentials (ERPs) in human subjects. Single sweep and averaged data were analysed in the time and frequency domains. Recognised peaks, seen in the averaged data, were related to specific poststimulus changes within conventional delta, theta and alpha frequency bands. The potential advantages of single sweep analysis, selective averaging and frequency domain analysis are discussed. The importance of studying prestimulus EEG activity in order to understand poststimulus changes is emphasised in relation to proposed hypotheses concerning brain dynamics and evoked response mechanisms. Specific frequency changes, elicited by target tones in auditory "odd ball" experiments, are described and contrasted to changes seen in EPs and nontarget ERPs. Our findings suggest that the P300 change of averaged data is the later consequence of poststimulus frequency changes which can be detected within the first 100 msec. The practical implications of our findings are briefly discussed.

Alpha Rhythm↗
PubMed1983

Event-related potentials in psychiatry: approaches to research and clinical applications.

This article suggests that the potential usefulness of event-related potentials in psychiatry has not been fully explored because of the limitations of various approaches to research adopted to date, and because the field is still undergoing rapid development. Newer approaches to data acquisition and methods of analysis, combined with closer co-operation between medical and physical scientists, will help to establish the practical application of these signals in psychiatric disorders and assist our understanding of psychophysiological information processing in the brain. Finally, it is suggested that psychiatrists should seek to understand these techniques and the data they generate, since they provide more direct access to measures of complex cerebral processes than current clinical methods.

Brain↗
PubMed1978

Computer analyses of auditory evoked cortical potentials in schizophrenic subjects.

Averaged cortical evoked potentials from single clicks were recorded from 51 patients and controls. The patient group consisted of 40 subjects with a diagnosis of 'nuclear' schizophrenia, and 11 subjects with diagnoses including mania, anxiety neurosis and personality disorder. Changes in auditory evoked cortical responses (AECR's) were most marked in clinically stable, dysphoric, chronic schizophrenics. These subjects showed reproducible, low amplitude, 'untidy' responses in which the amplitude of the primary peak was lower than the amplitude of later peaks. Chronic schizophrenics who were rated as being depressed, showed a more 'normal' AECR. AECR changes during the memorising of nonsense syllables demonstrated a functional separation between early and later peaks of the AECR. It was postulated that the AECR changes in schizophrenia and during memorising result from pathological patterns of cortical desynchronisation produced by altered mid-brain activity different from that of anxious arousal, and that the clinical 'steady-state' of chronic schizophrenia is reflected in the 'steady-state' desynchronisation changes in the AECR.

Acoustic Stimulation↗