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Biomedical subjects

S Shimojo

Publications and source records attributed to S Shimojo.

86 records · Page 5Linked to original sources
PubMed1985

Preferential-looking assessment of fusion and stereopsis in infants aged 1-6 months.

The ability of infants to discriminate zero-disparity stimuli from both reverse contrast (rivalrous) and disparate (stereoscopic) stimuli was investigated in a two-alternative, forced-choice, preferential-looking paradigm. Few infants under 4 months of age demonstrated discrimination for any stimulus pairing. Of the infants tested at 4 months of age, approximately 70% preferred zero-disparity stimuli to reverse contrast stimuli, and 82% preferred stereoscopic stimuli to zero-disparity stimuli. Nearly 100% of 5- and 6-month-old infants exhibited these preferences. These findings suggest that sensory fusion is not present at birth but develops rapidly over the first 6 months of life. The time course for the development of sensory fusion was similar to the time course for the development of stereopsis in nine infants tested longitudinally.

Adult↗
PubMed1984

Development of vernier acuity in infants.

The development of vernier acuity in human infants aged 2-9 months was assessed by a preferential looking procedure using a vernier-motion display. The displacement of vernier offsets gives the impression of motion only when the vernier offsets are detected. Grating acuity of the same group of infants was also measured by a preferential looking procedure. Vernier acuity was found to be superior to grating acuity only after 3 months of age. This superiority of vernier acuity was compared with the superiority of stereoscopic acuity to grating acuity. The two classes of hyperacuity proved to be almost equivalent in terms of their developmental time-courses. A common physiological basis for the development of hyperacuities is suggested.

Child Development↗
PubMed1981

Adaptation to the reversal of binocular depth cues: effects of wearing left-right reversing spectacles on stereoscopic depth perception.

The principle of stereopsis, that crossed disparity causes a convex perception and uncrossed disparity a concave one, has for a long time been considered to depend on a very rigid neural mechanism not affected by experience. Experiments are reported here which show that this relationship between disparity and perceived depth can be reversed by experience. An observer wore a pair of left-right reversing spectacles continuously for nine days. The spectacles also reversed the relation between the direction of perceived depth and the direction of binocular depth cues, ie disparity and vergence. For a period starting two days before wearing the spectacles and continuing until seventy-nine days after their removal the observer was examined with a haploscope and an electrooculograph. All the stereoscopic experiments were carried out without spectacles in order to examine some aftereffects of wearing spectacles. For the stereograms with linear contours not only the adaptive reversal of the relation between disparity and perceived depth, but also some abnormal depth perceptions and long-lasting aftereffects were found. For Julesz's random-dot stereograms, however, in which contours can be seen only after binocular combination, no adaptive change or reversal occurred. These results suggest that the process of stereopsis consists of two concurrent subprocesses.

Adaptation, Ocular↗
PubMed1979

Electromyographic study of patients with dysfunction of the Eustachian tube.

In order to determine how often dysfunction of the tube might arise from dysfunction of the tubal muscles, electromyographic examination of the muscles was carried out on 34 patients with occluded or patent tube. Using a monopolar needle electrode inserted through the nose, selective EMG of the tensor and levator veli palatini muscles were picked up during swallowing. It was found that the patients showed neither abnormally reduced nor increased muscle activity. Comparison of muscle activity of the normal tube and of both the occluded and patent tube revealed no significant differences. Therefore, myogenic cause of tubal dysfunction seems improbable from the clinical viewpoint.

Electromyography↗
PubMedDate not supplied

Herpes zoster ophthalmicus with delayed contralateral hemiparesis.

A 35-year-old previously healthy woman developed left hemiparesis sixteen weeks after the onset of right herpes zoster ophthalmicus. Cerebral angiography showed complete occlusion of right middle cerebral artery at the origin and segmental narrowing of the right posterior cerebral artery. Computerized tomography (CT) and magnetic resonance imaging (MRI) also revealed a right hemispheric lesion consistent with angiographic findings. Reports from the literature along with the present case suggest that arteritis followed by cerebral infarction is the most probable cause of delayed contralateral hemiparesis.

Adult↗