Conjugate Eye Deviation Research Articles

Corticocortical connections of frontal oculomotor areas in the cat

The corticocortical connections of the frontal ‘oculomotor’ areas related to eye movements of the cat were studied using the retrograde horseradish peroxidase (HRP) tracing method combined with electrophysiological techniques. The following results were obtained. (1) The medial wall of the hemisphere under the cruciate sulcus (CRU), where contralateral conjugate eye deviation was elicited, received fibers from the medial bank of the presylvian sulcus (PRE). The fundus of the coronal sulcus (COR), where monocular movement of the contralateral eye was evoked, received fibers from the lateral bank of the PRE. (2) All the frontal oculomotor areas, the medial wall of the hemisphere under the CRU, the fundus of the COR, and both banks of the PRE, received fibers from the ipsilateral ventral bank of the anterior ectosylvian sulcus (AES). (3) The ventral bank of the AES recieved fibers from the caudal part of the lateral suprasylvian visual areas. On the basis of the fiber connections, the frontal oculomotor areas can be subdivided into a ‘medial’ area, the medial wall of the hemisphere under the CRU and the medial bank of the PRE, and a ‘lateral’ area, the lateral bank of the PRE and the fundus of the COR. Moreover, we found evidence of fiber projections from the ventral bank of the AES to the frontal oculomotor areas that were physiologically identified.

Conjugate eye deviation after acute hemispheric stroke: delayed recovery after previous contralateral frontal lobe damage.

In 42 patients with acute unilateral ischemic or hemorrhagic hemispheric stroke, conjugate eye deviation toward the lesioned side was usually of brief duration. It subsided within 48 hours in 24 patients (57%) and lasted no longer than 5 days in 38 patients (90%). Early disappearance of conjugate eye deviation was an isolated phenomenon and preceded any improvement in the other focal neurological deficits, which persisted in their initial severity. In 6 additional patients with stroke, conjugate eye deviation was remarkably prolonged, lasting from 13 to more than 43 days. In all 6 there was evidence for preexisting damage to the contralateral frontal region. Our study suggests that early recovery of conjugate eye deviation in patients with acute hemispheric stroke may be mediated by the contralateral unaffected frontal eye field.

Role of the pulvinar-lateral posterior nucleus complex in turning behavior

The behavioral response to electrical stimulation of the pulvinar-lateral posterior complex (P-LP) was studied in 11 adult cats with chronically implanted electrodes. The EEG of P-LP, caudate nucleus, superior colliculus, dorsal hippocampus and cerebral cortex was recorded during the stimulation sessions. Three cats had a cannula implanted in one P-LP through which drugs were microinjected. Threshold currents evoked contralateral head turning and conjugate eye deviation, and suprathreshold currents induced contralateral circling. Ninety-four percent of 456 stimulations in P-LP elicited contralateral head movements. P-LP EEG did not differ from controls during head turning induced by threshold currents, but it was desynchronized with slightly suprathreshold currents and occasionally showed after-discharges, concomitant with circling, with higher currents. Microinjections of ACh, KCl (25%), and penicillin into P-LP also induced contralateral circling, which was usually followed by a generalized epileptic seizure. This would support the postulate that the behavioral responses observed through electrical stimulation were mediated by synaptic activities within the P-LP. These results indicate that P-LP is involved in turning and circling behavior.

Experimental regional cerebral ischemia in the middle cerebral artery territory in primates. Part 1: Angio-anatomy and description of an experimental model with selective embolization of the internal carotid artery bifurcation.

Selective embolization of the internal carotid artery bifurcation (ICA bifurcation) was performed in monkeys (Macaca mulatta) to study acute regional cerebral ischemia in the middle cerebral artery (MCA) territory with minimum surgical intervention in the neck under sedated conditions. The anthropomorphic similarity in angio-anatomy of the carotid system of monkeys and the use of silastic spheres, as artificial emboli, of the critical diameter of 1.2 to 1.4 mm resulted in the overall success rate of 87% in localizing the site of embolization to the ICA bifurcation, producing ischemia in the whole middle cerebral artery territory. All the animals with ICA-bifurcation embolization had contralateral deep motor weakness and conjugate eye deviation with nystagmus toward the site of embolization. Simultaneous EEG recording showed flattening of the basic background activities over the affected MCA area and cerebral arteriograms showed definite retrograde filling of the proximally occluded MCA. Clinical recovery was observed in a few animals within two to five hours of embolization. Gross ischemic swelling in the affected MCA territory, particularly in the gray matter, became obvious in six of eight animals which were exposed to four to five hours of ischemia. The angio-anatomical study of the carotid system of this experimental animal as a background for this MCA stroke model confirmed the previous observations of other investigators that the extremely abundant leptomeningeal anastomoses would be one of the major factors leading to the variability in the clinicopathological pictures seen in the models of proximal MCA occlusion. In addition, the pre-parenchymal anastomoses in the base of brain between the medial striate arteries from the proximal anterior cerebral (ACA) and lateral lenticulostriate arteries from the MCA were observed and described as a possible functional collateral to the basal ganglia in case of proximal MCA occlusion.

Vertical linear acceleration (otolithic-ocular responses).

AbstractA 60‐foot vertical linear acceleration device was used to present linear acceleration forces to test animals within a light sealed capsule. Two types of stimuli were used: !1. constant direction of force with rectilinear alterations of the acceleration rate (0 G and 2 G); and 2. constant direction with curvilinear alterations of the acceleration rates (0 to 2 G). Multiple cycles of alternating G forces were presented during a test run.Cats were used as the experimental animal. Eye movement recordings (vertical and horizontal) were made electronystagmographically. All linear acceleration tests were done in darkness. Analysis of data was done by evaluation of the direct recordings and by algebraic summation of consecutive acceleration cycles.The responses of normal and labyrinth altered cats were similar. Conjugate eye deviation was the most prominent response. Nystagmus rarely occurred. The direction of the conjugate deviation in unilaterally labyrinthectomized – contralaterally semicircular canal plugged preparations (unilateral otolithic animals), was of greatest magnitude when the acceleration force was parallel to the utricular plane from a medial to lateral direction. Reversal of position by 180d̀ generally caused reversal of the direction of conjugate eye deviation.The maximum eye deviation and/or production or alteration of nystagmus was related to the magnitude of jerk or, in other words, the rate of change of acceleration and not to the magnitude of acceleration (rate of change of velocity). The rate of change of acceleration at which these changes occurred was near 1.66G/sec (53 ft/sec3). Correlation with predicted planes from mathematical models is cited.The lack of nystagmus production in this study was contrasted to previous reports of nystagmus production by linear acceleration. It was suggested that nystagmus production by otolithic stimulation may be regularly present when the values of linear acceleration are closer to physiologic levels and/or when the otolithic surface is serially stimulated as when the axis of the resultant force changes direction.The variations in reproducibility of response patterns suggested a limited response range to linear acceleration of the (otolithic) vestibular‐ocular reflex.

Central eye nystagmus in the split-brain guinea pig

The purpose of the present investigation was to examine the effects of acute, midline, symmetrical splitting of different parts of the brain on eye nystagmus in the guinea pig. Nystagmus was elicited by electrical stimulation of the temporoparietal cortex or of the nystagmogenic corticofugal fibers in the superior colliculus, by thermal stimulation of the labyrinth. Midline, symmetrical division of the corpus callosum and diencephalon, of the mesencephalon, or of the rostral most part of the bulb just caudal to the abducent nuclei did not suppress the nystagmus. However, it was abolished by splitting the whole pontomesencephalic region or, more simply, the pons at the level of or just rostral to the abducent nuclei. In this instance labyrinthine or central stimulation could induce conjugate or monocular eye deviation only occasionally. In the guinea pigs with split mesencephalon, abnormalities of conjugate eye movements were observed during nystagmus, particularly when the vestibular nuclei were ablated together with the cerebellum. Thus, the central eye nystagmus was horizontal in one eye and vertical in the contralateral one; in other cases monocular or convergent nystagmus was noted.