PubMed Health⌕ Search

Biomedical subjects

C W Johnston

Publications and source records attributed to C W Johnston.

6 recordsLinked to original sources
PubMed1986

Hemi-inattention resulting from left hemisphere brain damage during infancy.

A case of right visual hemi-inattention is reported in a right-handed 14-year-old male who, as an infant, suffered a left hemisphere subdural hemorrhage and subsequently developed a large left posterior porencephalic cyst and right homonomous hemianopsia. Neuropsychological assessment reveals a significantly higher Verbal than Performance IQ, and evidence of hemi-inattention on tests of line bisection, picture matching from memory, and drawing figures from memory. Eye movement testing reveals poorer accuracy and latency of saccades for left-to-right eye movements than for right-to-left eye movements, but no appreciable difference in searching time for the left vs. the right visual spatial field. The findings are discussed in the context of developmental, educational, and rehabilitative implications with respect to the paucity of reports of visual hemi-inattention in children, and with consideration for effects unique to suffering a lesion in early infancy.

Adolescent↗
PubMed1986

Exploratory eye movements and visual hemi-neglect.

The severity of visual hemineglect (VHN), as defined by a VHN Index from scores obtained on letter cancellation and visual matching tests, was compared to eye movement behavior during a visual searching task in a group of right-hemisphere stroke patients and a group of age-matched normal controls. A strong negative correlation was obtained between the VHN Index and eye movement Exploration Time of the left visuospatial field for the stroke patients, but not for the control subjects. Further analyses failed to discriminate Exploration Time performance of stroke patients with mild VHN from the performance of control subjects, but did discriminate stroke patients with marked VHN from each of these two groups. Covarying for the presence of a left-visual-field sensory defect slightly reduced the significance level of this finding. The results and questions raised by this study are discussed in the context of developing an operational definition for VHN using the method of directly monitoring eye movement.

Aged↗
PubMed1979

Oculomotor programming disturbances in the dementia syndrome.

Three types of oculomotor programming disturbances are described in patients with the dementia syndrome. This report describes two of these abnormalities, poorly regulated gaze patterns and a programming type of gaze perseveration. All patients showed poorly regulated gaze patterns in contrast to the normal controls, whereas on the whole only the moderately affected patients showed the programming type of gaze perseveration. The third type of oculomotor programming disturbance is efferent perseveration of gaze (a hypokinetic, "staring" type of gaze pattern) and can be seen with severe dementia. The possible significance of these findings is discussed.

Aged↗