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J C Doyle

Publications and source records attributed to J C Doyle.

5 recordsLinked to original sources
PubMed1979

Electroencephalogram correlates of higher cortical functions.

By means of two-stage, nonlinear multivariate pattern recognition, electroencephalograms (EEG's) were analyzed during performance of verbal and spatial tasks. Complex scalp distributions of theta-, beta-, and, to a lesser extent, alpha-band spectral intensities discriminated between the two members of a pair of tasks, such as writing sentences and Koh's block design. Small EEG asymmetries were probably attributable to limb movements and other uncontrolled noncognitive aspects of tasks. Significant EEG differences beteeen cognitive tasks were eliminated when controls for inter-task differences in efferent activity, stimulus characteristics, and performance-related factors were introduced. Each controlled task was associated with an approximately 10 percent reduction, as compared with visual fixation, in the magnitude of alpha- and beta-band spectral intensity. This effect occurred bilaterally and was approximately the same over occipital, parietal, and central regions, with some minor difference over the frontal region in the beta band. With these controls, no evidence for lateralization of different cognitive functions was found in the EEG.

Adult↗
PubMed1979

EEG patterns during 'cognitive' tasks. I. Methodology and analysis of complex behaviors.

This paper presents a methodology which uses nonlinear pattern recognition to study the spatial distribution of EEG patterns accompanying higher cortical functions. The multivariate decision rules reveal the essential EEG patterns which differentiate performance of two tasks. Cross-validation classification accuracy measures the generality of the findings. Using this method, EEG patterns were derived from a group of 23 adults during performance of several complex tasks, including Koh's block design, writing sentences, mental paper folding, and reading silently. These patterns discriminate between the tasks, are consistent with, and extend the results of, visual EEG interpretations and univariate analysis of spectral intensities. Since writing sentences could not be distinguished from mere scribbling, it is unclear whether the EEG patterns found to distinguish complex behaviors were related to the cognitive components of tasks, or to sensory-motor and performance-related factors.

Adult↗
PubMed1979

EEG patterns during 'cognitive' tasks. II. Analysis of controlled tasks.

This experiment was designed to distinguish possible EEG correlates of the cognitive components of tasks from EEG patterns associated with stimulus characteristics, limb and eye movements, and performance-related factors such as subjects' ability and effort. Thirty-two right-handed adults each performed 30 trials, lasting 6-15 sec each, of four simplified, controlled tasks: mental rotation of geometric forms, serial addition of a column of signed digits, substitution of letters with subsequent word recognition and visual fixation. The first three tasks could not be differentiated from each other. Each of these tasks could be differentiated from visual fixation by approximately 10% generalized reductions in alpha and beta band intensities, and slight increases in theta band intensities frontally and occipitally. We conclude that the EEG patterns which differentiated the complex tasks described in Part I were due to inter-task differences in stimulus characteristics, efferent activities and/or performance-related factors, rather than to cognitive differences. With these controls, no evidence for lateralization of different types of cognitive activity was found in the EEG.

Adult↗
PubMed1977

Acute mesenteric ischaemia.

The experience of acute mesenteric ischaemia at St Vincent's Hospital, Melbourne, has been reviewed over 17 years. The mortality remains appallingly high. This applies particularly to those patients who had thrombosis of the superior mesenteric artery, amongst whom the mortality in this series was 97%. The mortality was slightly less in the group suffering from embolic occlusion of the superior mesenteric artery (66%), and in those suffering from thrombosis of the superior mesenteric vein (60%). A mortality of 66% was also found in patients suffering from non-occlusive gut ischaemia. Delay in diagnosis accounted for this high mortality. Early diagnosis is all-important, and this depends on the performance of mesenteric angiography in any patient suspected of having mesenteric ischaemia. Appropriate surgery may then be carried out in the occlusive group and supportive treatment, including intraarterial papaverine infusion, given to those with non-occlusive ischaemia. There is a pressing need for simple non-invasive tests to segregate those patients suffering from acute mesenteric ischaemia from those whose acute abdomen is due to some other cause.

Acute Disease↗