Jun Tsutsui

Projections of extraocular muscle afferents to the visual cortex in the cat

A patient with transient monocular rotary-vertical nystagmus demonstrated decreased gain of vertical pursuit and normal vestibulo-ocular reflex on electrooculogram. A supranuclear brain stem lesion, resulting in lack of monocular inhibition of oculomotor neurons, is postulated on the basis of these findings.

Electrophysiological and pathological studies on Creutzfeldt-Jakob disease with retinal involvement

In a case of Creutzfeldt-Jakob disease in a 59-year-old female, multifocal degeneration from the cerebral cortex through the visual pathway to the retina was detected clinically, electrophysiologically, and pathologically.Visual evoked cortical potentials (VECPs) showed a peculiar huge negative wave in the early stage but the amplitude reduced gradually. The a- and b-waves of the ERG were detectable in the final stage. Dynamic topography of VECPs revealed a delay of excitation in the visual cortex in the early stage, but a complete defect of the cortical potential and diminished reactivity of the brain stem were apparent in the later stage.Pathological findings were the spongy degeneration of the cerebral cortex, demyelination of the white matter and the optic pathway, and the degeneration of the nerve fiber layer and ganglion cell layer of the retina.

Average responses evoked by moving grating pattern in the upper, central and lower visual field

Detectable visual evoked potentials were obtained in man by stimulation in the peripheral visual field with a 0.4 cycle/deg vertical grating pattern of 5 degrees arc subtense which moved twice per second horizontally at 415 degrees/sec through an amplitude of 8 degrees arc. These moving grating stimuli were presented to 10 normal subjects, centered 15 degrees above, or centered around, or centered 15 degrees below a fixation mark. The mean latencies (+/- S.D.) of the positive component of the potential evoked by stimuli to the central and 15 degrees eccentricity lower visual field were 114 +/- 17 msec and 104 +/- 20 msec, respectively, while latencies for 15 degrees eccentricity upper visual field stimuli were significantly (p less than 0.001) later with 148 +/- 20 msec.

Studies on short latency visual evoked potentials in cases with optic pathway lesions

Four patients who attempted suicide by using handguns survived bilateral optic nerve destruction with limited additional neurological damage.

Dynamic topography of the human short latency visual

Topographic analysis of the very early components of visual evoked potentials was carried out to demonstrate a visual conduction from the retina to the visual cortex through the brainstem. These potentials are called short latency visual evoked potentials (SVEP). In SVEP, at least four oscillatory potentials of the retina project a weak negative firing for the optic nerve and the brainstem four times, respectively, during a 20 msec to 55 msec period. Subsequently, the first occipital response appeared at 40 msec and the second one at 65 msec. Consequently, three groups of responses such as the retinal potentials, the optic pathway and brainstem potentials, and the occipital potentials were detected in human SVEP.

Studies on Visual Evoked Cortical Response by Liquid Crystal Phase Difference Haploscope: Amblyopia and/or Strabismus

Visual evoked cortical potentials induced by alternate stimulation of checkerboard pattern with the use of liquid crystal phase difference haploscope were investigated. The synchronization ratio of brain response was determined both in the group of normal binocularity and in the group with binocularity defect. The synchronization ratio of the group of normal binocularity (N = 30) is 100% at 1 Hz x 2, 98.5% +/- 3.9% at 5 Hz x 2, and 83.7% +/- 15.8% at 10 Hz x 2. On the other hand, in the group with binocularity defect, strabismus without amblyopia shows a reduction of the ratio only at the frequency of 10 Hz x 2. Anisometropic amblyopia shows a significant reduction of the ratio at 10 Hz x 2 and strabismus with amblyopia shows a remarkable reduction at 5 Hz x 2 and 10 Hz x 2. As for strabismus with or without latent binocularity, the latter cases show a significant reduction of the synchronization ratio. The reduction of synchronization ratio of VECP seems to have some relationship to the binocularity.

Short latency visual evoked potentials in functional amblyopia shown using moving topography

The conduction from the eye to the visual cortex through the brainstem was investigated in 43 cases of functional amblyopia by means of moving topography of short latency visual evoked potential (SVEP). Anomally of the SVEP such as a defect of the main component and remarkable reduction of amplitude was found in cases with severe amblyopia whose visual acuity was less than 0.5. The incidence of abnormal SVEP was recognized in 44% of anisometropic amblyopia (18 cases), 52% of strabismic amblyopia (15 cases), and 50% of deprivation amblyopia (10 cases). The results suggested a reduction of electric activity in the subcortical visual pathway including transmitting nuclei.

Ocular motor apraxia and lesions of the visual association area

A 51-year-old female suffered from atypical ocular motor apraxia. Neither smooth pursuit nor saccadic eye movements could be elicited by visual stimuli, but saccadic eye movements were induced by verbal stimuli. The vestibulo-ocular reflex (VOR) was normal. The visual evoked cortical potential (VECP) showed a low occipital response and a normal vertex potential. The autopsy results showed old softenings in the bilateral occipital lobes and cerebellum. The lesion in Area 18 seemed to account for the absence of visually elicited eye movements. The severity of the damage to the occipital lobes corresponded with the reduction of the VECP.

Activity balance of electromyograms in intermittent exodeviation

Electromyograms of the four horizontal rectus muscles were recorded in intermittent exodeviation. Based on the activity balance between the medial and lateral rectus muscles during exodeviation, subjects were divided into the following types; in Type I, lateral rectus activity was more than that of the medial rectus; in Type II, activity was well balanced; and in Type III, medial rectus activity was more than that of the lateral rectus even during exodeviation of the eyes. The mean age and mean deviating angle increased in the order I, II, III. It was concluded that the electrical activity of the horizontal muscles in intermittent exodeviation varies widely and that active divergence is dominant in Type I, whereas compensatory active convergence is dominant in Types II and III.

Topographic EEG maps by various normal visual functions

Characteristic EEG topograms which were evoked by various visual functions and often appeared with high reproducibility were classified for standardization in clinical use. The following seven types of topograms were selected. Retinal potentials on the prefrontal region were obtained in flash visual evoked potential (VEP), which included short latency VEPs. It appeared only in the frontal region and never extended to the posterior region. Optic pathway potentials were demonstrable as very weak negative far field potentials appearing after each oscillatory potential of the retina. Brainstem potentials were represented by the far field potentials in the short latency VEP at about 50 msec and this seemed to be related to pupillary light reaction. The premotor spike positive potential was also detected as a brainstem potential. Occipital potentials appeared as visual cortex responses represented by P100. Wide field stimuli provoked convex discharge indicating an excitation of the whole visual cortex. Occipito...