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Biomedical subjects

C J Lueck

Publications and source records attributed to C J Lueck.

25 records · Page 2Linked to original sources
PubMed1990

Auditory-visual interaction in the generation of saccades in man.

Four normal human subjects were investigated for evidence of auditory-visual interaction in the generation of horizontal saccades. In a first experiment it was shown that the mean amplitudes of initial saccades from primary position to auditory targets were significantly affected by the simultaneous occurrence of a distracting visual stimulus. If both auditory and visual stimuli were in the same hemifield, the mean amplitude of initial saccades to a fixed buzzer position was consistently increased or decreased depending on the position of the visual stimulus. The phenomenon is felt to be analogous to the "centre-of-gravity" effect previously described for two simultaneous visual stimuli. It did not occur if visual and auditory stimuli were in opposite hemifields when a simultaneous visual stimulus caused a slight reduction of mean initial saccadic amplitude compared to the mean amplitude to buzzer alone. In this case the reduction was independent of visual stimulus position. Similar effects were seen for mean final eye positions. In a second experiment, a similar procedure was carried out, but the eyes started by looking at a point at 15 degrees eccentricity. The same pattern of auditory-visual interaction was obtained in both experiments, consistent with the concept of eye-movement related movement of modality-specific sensory "maps" which has recently been shown to occur in the superior colliculus of primates.

Acoustic Stimulation↗
PubMed1990

Saccadic eye movements in essential blepharospasm.

To provide evidence of an organic pathology for essential (idiopathic) blepharospasm, reflex saccadic eye movements in response to randomly stepped visual targets were assessed in seven affected patients and seven age-matched controls using the magnetic scleral search coil technique. The results indicate a significant prolongation in latency and a reduction in gain of horizontal saccades, and an increase in latency and reduction of peak velocity of large downward saccades. These findings suggest an organic component to the aetiology of blepharospasm, the pathology of which also appears to involve the oculomotor system. The pattern of the oculomotor disorder does not allow specific localisation but is consistent with the underlying pathology being localised in the basal ganglia.

Adult↗
PubMed1990

Antisaccades and remembered saccades in Parkinson's disease.

Antisaccades were studied in ten patients with mild to moderate Parkinson's disease and ten age-matched normal controls. Remembered saccades and reflex saccades were assessed for comparison. In the population of patients who showed the previously reported abnormalities of remembered saccades, antisaccades were indistinguishable from those of controls in latency, gain and peak velocity. This finding implies that antisaccades are mediated through pathways which are unaffected by Parkinson's disease, and which are therefore presumably distinct from pathways mediating other voluntary saccades.

Aged↗
PubMed1989

The colour centre in the cerebral cortex of man.

Anatomical and physiological studies have shown that there is an area specialized for the processing of colour (area V4) in the prestriate cortex of macaque monkey brain. Earlier this century, suggestive clinical evidence for a colour centre in the brain of man was dismissed because of the association of other visual defects with the defects in colour vision. However, since the demonstration of functional specialization in the macaque cortex, the question of a colour centre in man has been reinvestigated, based on patients with similar lesions in the visual cortex. In order to study the colour centre in normal human subjects, we used the technique of positron emission tomography (PET), which measures increases in blood flow resulting from increased activity in the cerebral cortex. A comparison of the results of PET scans of subjects viewing multi-coloured and black-and-white displays has identified a region of normal human cerebral cortex specialized for colour vision.

Cerebral Cortex↗
PubMed1989

Oculomotor abnormalities in diseases of the basal ganglia.

Disorders of eye movements have been described in diseases of the basal ganglia for over a century. Recent neurophysiological and clinical work has greatly clarified the oculomotor role of these structures: their major involvement appears to be in the generation of "voluntary" saccades, and in the suppression of "reflex" saccades. The observed abnormalities of saccadic eye movements in Huntington's (HD) and Parkinson's (PD) diseases conform very well to predictions based on a combination of known disease pathology and recent neurophysiological work. This is not quite the case for other types of eye movement, such as smooth pursuit, largely because the exact role of the basal ganglia in their generation has not been defined neurophysiologically. Several diseases other than HD and PD both involve the basal ganglia and have effects on eye movements; such diseases include progressive supranuclear palsy and Wilson's disease. Unfortunately, the pathological processes in these conditions are too widespread to allow comment on how well oculomotor abnormalities fit in with predictions.

Eye Movements↗
PubMed1989

Unilateral reversal of smooth pursuit and optokinetic nystagmus.

A patient is presented who has had three six-month episodes of oscillopsia over the last eight years. During the episodes, abnormal smooth pursuit and optokinetic nystagmus were noted, but there were no other abnormalities. Oculography during the most recent episode demonstrated that when tracking from right to left, the patient's smooth pursuit was reversed. There are several features of the case which suggest that the aetiology may be a form of congenital nystagmus. A possible alternative mechanism whereby such an abnormality might arise as an acquired lesion is discussed.

Adult↗