Biomedical subjects

R R Kydd

Publications and source records attributed to R R Kydd.

22 records · Page 2Linked to original sources

PubMed1984

A test for constant natural frequencies in electrocortical activity under lateral hypothalamic control.

An initial test for a theory of lateral hypothalamic regulation of electrocortical activity is undertaken. The theory supposes lateral hypothalamic input directly or indirectly damps telencephalic resonances involving linear wave phenomena, enabling this pathway to act as parametric control of information processing in cortical neural networks. Relative changes in left and right electrocortical power spectra are used to test for the presence of resonant modes with constant natural frequencies in conditions of asymmetrical damping, following unilateral lesion of the lateral hypothalamus. Natural frequency values for the modes clustered about center frequencies in the EEG band are obtained. This method has the advantage of minimising the effects of time-variation and the recorded signal's distortion from the electrocortical local spatial average, but limits consideration to five dominant modes of resonance. The uncertainty of true model order, and errors in curve-fitting impose limitations on the test.

Animals↗

PubMed1984

Inference of a stable dispersion relation for electrocortical activity controlled by the lateral hypothalamus.

A second test is undertaken for a theory of linear wave motion in electrocortical waves, under lateral hypothalamic control via regulation of damping. This test invokes a general property of linear systems, namely that wave motion with characteristic natural frequencies implies fixed phase velocities associated with each wavelength, independent of the changes in hypothalamic input. A means of testing the invariance of this dispersion relation at the point of recording is derived from a simplified biophysical model for waves in a dipole layer. The method avoids some problems implicit in direct spatio-temporal wave analysis. Results confirm that the model under test is internally consistent, and is also consistent with other findings concerning the origin and spatial nature of the EEG.

Animals↗

PubMed1982

Schizophrenia in children under 16 years.

Schizophrenic children admitted as inpatients to a child psychiatric unit over a 10-year period were reviewed in terms of demographic characteristics, clinical features, and social adaptation using the DSM-III as a frame of reference. Ten children who were first seen at least 1 year previously were followed up and reassessed as regards clinical status and level of adaptive functioning. As in other studies, outcome was related to age at onset, premorbid level of adaptation, rapidly of onset, clinical subtype, and presence of affective symptoms. However, deterioration following the active phase of the illness occurred in only four cases. The outcome in childhood schizophrenia may be more favorable than generally assumed, but there is a need for longer and larger studies of carefully diagnosed groups.

Adaptation, Psychological↗

PubMed1980

Self poisoning: who supplies the drugs? 100 examples.

One hundred self-poisoners, consecutively referred to the psychiatric liaison service at Auckland Hospital were questioned regarding the source of the substances taken, the taking of regular medication and their last contact with a doctor. In total, 82 percent took legitimately prescribed medications, in 67 cases prescribed for themselves, while 12 percent bought over-the-counter preparations. Alcohol was associated in one-third of all cases. In one half of all cases the substance ingested had been prescribed at the last visit to a doctor. These patients were statistically more likely to be depressed, to be taking regular medication and to have taken a previous overdose. Two-thirds of all cases had seen a doctor no more than a month prior to self-poisoning.

Adolescent↗