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T Warabi

Publications and source records attributed to T Warabi.

18 recordsLinked to original sources
PubMed2000

Cerebral blood flow on xenon CT: correlation with the blood flow detected at the common carotid artery on ultrasonography.

To correlate cerebral blood flow (CBF) on xenon CT with the flow at common carotid artery (CCA) detected by color doppler ultrasonography, 82 patients (29 men, 53 women; 20-90 yrs) were examined. They included normal volunteers (n = 33), patients with cerebral infarction (n = 8), multiple lacunar infarcts (n = 12), dementia (n = 14), and parkinson disease (n = 15). Flow at the CCA was graded as extremely low (< 0.3 l/min), low (0.3-0.4), and normal (> 0.4). CBF was measured in the following distribution: anterior, middle, posterior cerebral arteries (ACA, MCA, PCA); white matter border zones (BZ); basal ganglia (BA), thalamus in two slices. CBF may be reduced in the BZ, cortical and deep gray matter with extremely low flow at CCA. We suggest that color doppler ultrasonography may aid in triage of patients for further CBF evaluation. As some overlap in CBF exists between normal and diseased groups with respect to low flow at CCA, color doppler ultrasonography must be evaluated in combination with xenon CT to reflect cerebral blood flow.

Adult↗
PubMed1995

[Neuro-psychiatric involvement in primary Sjögren's syndrome].

Neuro-psychiatric involvement in primary Sjögren's syndrome (PSJS) has been summarized according to the literature. Sjögren's syndrome is an autoimmune disorder with a predilection for multi-system involvement. Recently, disorders of the peripheral nervous system (PNS) and central nervous system (CNS) in PSJS, as well as, other organ involvement has been reported increasingly. However, CNS involvement, including the symptoms mimicking multiple sclerosis in PSJS is a controversial issue. There is discrepancy in the frequency of CNS involvement in PSJS among investigators. As for psychiatric manifestations in PSJS, descriptions have been made by many investigators. Depression and anxiety are the most common psychiatric manifestations in PSJS. About 10% of the patients with SJS have a neuropathy which tends to predilect for trigeminal nerve involvement. Further investigations elucidating the mechanisms of neuro-psychiatric involvement in PSJS is required.

Central Nervous System Diseases↗
PubMed1991

Converging eye movements evoked by microstimulation of the fastigial nucleus of macaque monkeys.

Stimulation of the dorsal part of the fastigial nucleus in macaques is known to evoke ipsilateral saccades, while those of the ventral part produce contralateral saccades. It was found that stimulation of the transitional zone moved the visual axis (eyes) to converge at an area (focus) in the oculomotor range, regardless of the initial eye position. These saccades were designated as 'converging saccades'. Converging saccades were directed to the focus, but the eyes did not attain the focus in one motion. Only the repetition of stimuli brought the eyes near the focus. When stimulation is applied to the transitional zone at progressively more ventral sites, the focus gradually shifted, starting from the ipsilateral hemifield to the contralateral hemifield by taking various routes.

Animals↗
PubMed1991

Effects of fastigial stimulation upon visually-directed saccades in macaque monkeys.

When the initial eye position was changed by stimulating the fastigial nucleus prior to visually-directed saccades, monkeys could not compensate for the stimulation-induced movement. The line of sight missed the target location by a distance and direction almost equal to the vector of the evoked saccade. When the stimulation was delivered 75-130 ms after the target presentation, saccades were triggered prematurely. Their initial movement reflected only the evoked saccade in some response and reflected the vector sum of the evoked and visually-directed saccades in the other. In contrast, when stimulus latencies were greater than 130 ms. saccades started toward the target location. The visuomotor processing for saccades seemed to be completed during this period, which is approximately half the latency of normal saccades. When the stimulation was applied while the eyes were already in motion, the trajectories of the saccades were strongly modified and terminated in deviated locations. These results indicate that cerebellar output impulses are projected downstream to saccade-programming circuits where visual information has already been converted into motor-command signals.

Animals↗
PubMed1990

Recovery of voluntary movement in hemiplegic patients. Correlation with degenerative shrinkage of the cerebral peduncles in CT images.

The severity of the disorder of voluntary movement in 89 chronic hemiparetic patients was correlated with the degenerative reduction of descending fibres evaluated by the magnitude of the shrinkage of the cerebral peduncles (CP) in computed tomographic (CT) images. The severity of hemiplegic posture and motor disturbance in the proximal and distal muscles was related to the total amount of residual descending fibres in the CP. In all patients whose CPs were less than 60% of the normal size, recovery from disturbance in reaching and grasping movements and impairment of relative independent finger movements was incomplete. Recovery of these movements occurred when more than 60% of the CP was spared and the degree of recovery from motor weakness was positively correlated with the quantity of intact fibres spared (residual CP ratio). The ability to perform fine and discrete movements with the fingers, known to be an essential function of the pyramidal system, was consistently impaired in patients with severe shrinkage involving the medial division of the CP. There was no particular correlation between the CP shrinkage and neurological signs such as spasticity, hyperreflexia, and pathological reflexes.

Adult↗
PubMed1988

Changes in strategy of aiming tasks in Parkinson's disease.

Fundamental differences in bradykinesia in parkinsonian patients and nonparkinsonian elderly subjects were analysed. Our method was an aiming task in which the coordination of eye and hand movements was measured when the subject attempted to catch up with a visual target. The coordinated eye and hand movements started towards the target almost simultaneously in the normal subjects when the target was in the periphery of the visual area. The initial abnormality in parkinsonian patients was an isolated delay of coordinated hand movement. In the typical bradykinetic patients, the hand movement did not start while the target was still in the peripheral visual area but only when the image of the target was near or on the fovea. The aiming tasks were then performed step by step following visual confirmation. Thus patients with typical bradykinesia showed a failure of ballistic hand movement preprogrammed to the visual target in the peripheral visual area, and the strategy of coordination was changed. In contrast, the disturbance of the ballistic hand movement in the nonparkinsonian elderly subjects had no consistent strategy for coordination of the visually guided eye and hand movements.

Aged↗
PubMed1987

Computed tomographic studies of the basis pedunculi in chronic hemiplegic patients: topographic correlation between cerebral lesion and midbrain shrinkage.

A computed tomographic method for analyzing the shrinkage of the basis pedunculi (BP) due to the secondary degeneration of the descending fibers was applied in correlation to the site of cerebral lesions in 89 chronic hemiplegic patients. Cerebral lesions in the anterior corona radiata or the anterior limb of the capsula interna caused shrinkage of the medial BP. Lesions in the central corona radiata or the genu and posterior limb of the capsula interna caused shrinkage of the central BP, while lesions of the posterior corona radiata or the posterior limb of the capsula interna caused shrinkage of the lateral BP. These results suggested that CT images are able to reveal the principle sites of atrophy of the descending fiber tracts in chronic hemiplegia.

Adult↗
PubMed1987

Response properties and visual receptive fields of climbing and mossy fibers terminating in the flocculus of the monkey.

Response properties and visual receptive fields of climbing fibers and mossy fibers terminating in the cerebellar flocculus were studied in monkeys trained to fixate a stationary visual target. Among a total of 429 climbing fiber-related units (climbing fibers and complex spikes of Purkinje cells), 20 (4.9%) showed cyclic modulations in firing in response to sinusoidal retinal-slip velocities. Their receptive fields always included the fovea. Among 485 mossy fibers, 64 (13%) responded to the visual stimulation. Of the 64 visually responsive mossy fiber units, 39 (61%) responded exclusively to the retinal-slip velocity (visual mossy fibers and the remaining 25 mossy fibers (39%) responded also to the eye and head velocities (visuomotor mossy fibers). Receptive fields for 17 visual mossy fibers (17/39 or 44%) were within 10 degrees of fixation and those for 22 others (56%) were in the periphery. Receptive fields for all 25 visuomotor mossy fibers were in the periphery. Each mossy fiber unit had a unique velocity-tuning curve and, therefore, the response patterns of individual mossy fibers were different depending on the range of their velocity sensitivity and on the retinal-slip velocity applied.

Action Potentials↗
PubMed1987

Responses of Purkinje cells and mossy fibres in the flocculus of the monkey during sinusoidal movements of a visual pattern.

1. Discharges of Purkinje cells (P cells) and mossy fibres were recorded from the cerebellar flocculus of monkeys trained to fixate a stationary visual target. The units were tested with a sinusoidally moving random dot pattern (background) which was projected on an entire screen or on part of it. The receptive field organization of the units was tested by changing the area of stimulus presentation on the screen and by changing the direction of visual fixation. 2. When stimulated with sinusoidal movements of the background in the horizontal plane, ninety-two of 684 Purkinje cells (13.5%) responded to the retinal-slip velocity. Seventy-eight of the ninety-two visually responsive Purkinje cells (84.8%) also showed cyclic modulations in activity during horizontal smooth-pursuit eye movements (these were so-called horizontal gaze-velocity Purkinje cells). 3. In response to the sinusoidal retinal-slip velocity, the visual Purkinje cells showed six types of discharge patterns. Type 1 Purkinje cells (28/92 or 30.4%) were directionally selective: they showed a peak activity during background movement in one direction and a trough in the other. Both peaks and troughs were related to stimulus velocities. Their receptive fields were relatively large (greater than 45 deg) and included the fovea. 4. Type 2 (8/92 or 8.7%) and type 3 (5/92 or 5.4%) Purkinje cells showed sinusoidal responses similar to those of type 1 Purkinje cells, but the visual inputs were primarily excitatory in type 2 Purkinje cells and inhibitory in type 3 Purkinje cells. Only the peaks in type 2 and troughs in type 3 were related to stimulus velocities. 5. Type 4 (4/92 or 4.3%) and type 5 (11/92 or 12.0%) Purkinje cells showed responses to stimulus movements in both directions (bidirectional). When the moving background was projected with 10 deg of fixation, type 4 Purkinje cells were excited bidirectionally in relation to retinal-slip velocities. When the periphery of either hemiretina was stimulated, type 5 Purkinje cells were inhibited and the trough activity was stimulus-velocity dependent. Receptive fields were found in the ipsilateral hemiretinae in seven type 5 Purkinje cells and in the contralateral hemiretinae in the remaining four type 5 Purkinje cells. 6. Type 6 (36/92 or 39.1% Purkinje cells received an excitatory input from the central retina and an inhibitory input from the periphery. The peripheral receptive fields were either in the ipsilateral (69.4%) or contralateral (30.6%) hemiretinae of both eyes.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1986

Discharges of Purkinje cells in monkey's flocculus during smooth-pursuit eye movements and visual stimulus movements.

Modulations in discharges of Purkinje cells (P cells) associated with movements of visual patterns were studied in the flocculus of monkeys trained to execute smooth-pursuit eye movements and to suppress optokinetic nystagmus. One class of P cells responded to the movements of visual stimulus regardless of whether the eyes remained stationary (produced retinal-slip velocity) or moved with the stimulus produced eye velocity). These P cells processed high-order information concerning the absolute velocity of stimulus movements and thereby the eye velocity had already been incorporated in the visual responses (visuomotor P cells). The other class of P cells responded to visual inputs resulting from the retinal slip (visual P cells). The majority of visual P cells (82%) also modulated their activities during smooth pursuit. When sinusoidal trackings were executed against a stationary visual background, various types of interactions occurred in the P-cell responses between the converging visual and oculomotor inputs. The type of interaction was related to the preferred direction for the P cell during eye movements and the side of the peripheral receptive field.

Animals↗
PubMed1986

Effect of aging on sensorimotor functions of eye and hand movements.

Changes in coordinated eye and hand movements with aging were studied in normal young and elderly subjects. Electrooculograms, flexor and extensor electromyograms, and potentials representing hand movements were recorded and used to evaluate the performance in aiming tasks. The parameters that reflect motor functions did not change significantly with aging in both eye and hand movements. However, elderly subjects commonly showed increases in reaction times of the initial (open-loop) movements in both eye and hand movements. Interestingly, the time increments were almost equivalent in these two functionally distinct motor systems. The durations of error-correcting (closed-loop) movements also increased significantly with aging in both motor systems. These increases suggest that the aging effects are the manifestation of impairment in the sensory process.

Adult↗
PubMed1986

Changes in sensorimotor function associated with the degree of bradykinesia of Parkinson's disease.

Changes in coordinated eye and hand movements associated with the progress of bradykinesia were studied in 31 parkinsonian patients and 8 age-matched healthy subjects. Among the parameters expressing the changes in motor behaviour, the interval between the onset of eye and hand movements was most sensitive. This parameter reflected the difference in the progress of the symptom in the two motor systems. An increase in the reaction time of the hand response appeared in patients of grade II bradykinesia; this was observed for eye movements only in patients with grade III (severe) bradykinesia. While the changes in ocular reaction time remained within the physiological range, a lengthening of the reaction time, a reduction in peak velocity, a decrease in the open-loop gain, a prolongation of movement duration, and a slow build-up in EMG activity, appeared from an early stage in hand movement. These signs of motor disturbance may appear eventually in every motor system at an advanced stage, but their development is not synchronous in different motor systems. An analysis of the responses recorded simultaneously from the two motor systems examined made it possible to evaluate the changes in the sensorimotor processes with different grades of bradykinesia. A comparison between reaction times for eye and hand movements may be useful for assessing the degree of bradykinesia in parkinsonian patients.

Adult↗
PubMed1984

Effect of aging on the accuracy of visually guided saccadic eye movement.

Changes in oculomotor behaviors with aging were studied in normal young and elderly subjects. Saccadic eye movements induced by presentation of a visual target were analyzed. Elderly subjects commonly showed an elongation of the time to locate the target, accompanied by an increase in reaction times (mean increase, 100 ms) and a decrease in saccadic velocities. The decrease in the velocity was particularly notable when a large-amplitude saccade was executed. In spite of the slowed motor responses, most elderly subjects preserved the function necessary to execute a correct saccade toward the visual target. The saccadic slowing was accompanied by an increase in saccade duration. Although a longer time was necessary for elderly subjects to locate the target, the accuracy of the initial saccades was not different from that of young subjects. One group of elderly subjects showed extremely long reaction times. These subjects, displaying no abnormal neurological symptoms, were not able to locate the visual target with initial saccades. They had to execute multistep saccades typically seen in patients with degenerative neurological diseases.

Adult↗
PubMed1982

Eye position signals in the flocculus of the monkey during smooth-pursuit eye movements.

1. Discharges of Purkinje cells and mossy fibres were recorded from the flocculus of monkeys trained to fixate a small visual target and to track the target when it moved slowly.2. Discharges of Purkinje cells changed tonically with shifts of gaze. Firing rates were linearly related to eye positions for either the entire or more than half the eye-position range in 12.6% of Purkinje cells tested (76/603 units).3. The eye position-related activity (position component) was observable in these cells also during smooth-pursuit eye movements. It was typically seen during slow eye movements (velocities less than 10 deg/s) but became undetectable during high velocity movements (faster than 50 deg/s).4. The position component became prominent when smooth pursuit was executed at the preferred loci of the individual cells. In the majority of the cells tested at their preferred loci, the position component was observable to a relatively high frequency, such as 0.5 Hz (+/- 10 deg; peak velocity 31 deg/s).5. Forty-five mossy fibre units showed saccade-related bursts and position-related intersaccadic tonic activity during steady eye position. In each unit, the position component was found only during fixations within a specific range of eye positions. During fixations outside these regions, all position-related mossy fibres were completely silent.6. During sinusoidal smooth-pursuit eye movements, the mossy fibres also displayed cyclic modulations in activity. All fibres discharged with eye movements in one direction and were silent during eye movements in the other direction.7. Saccade-related bursts from mossy fibres led the onset of saccades, ranging from 0 to 19 ms with a mean lead-time of 6.9 ms. This observation negates the possibility that the position-related signals might represent proprioceptive impulses from the stretch receptors of the extraocular muscle.

Action Potentials↗
PubMed1979

Trunk-ocular reflex in the rabbit.

The trunk-ocular reflex of the rabbit was investigated by recording EMGs of right lateral rectus and splenius muscles. The skull and the chest of the rabbit were restrained and the lower part of the trunk was flexed laterally around the axis at the TH10--11 intervertebral joint. Two kinds of eye movements, small with short latencies and large with longer latencies, were induced counter to the direction of the lateral flexion. The latency of the former was 158 msec (range: 64--200 msec) and that of the latter was 255 msec (range: 180--380 msec).

Abdomen↗
PubMed1979

[Neural mechanisms of group I fibers of neck muscles (author's transl)].

Afferent projection of upper cervical dorsal roots C2 and C3 upon spinal cord and brain stem was investigated on cats using both histological and electrophysiological methods. 1. Degenerated terminals, stained by Fink-Heimer's methods, were found in Rexed's laminae III and IV, intermediate nucleus and ventral horn of the spinal cord and nucleus cuneatus and spinal trigeminal nucleus. 2. Monosynaptic reflex responses were obtained from motor nerves innervating dorsal neck muscles by stimulating the dorsal roots in some decerebrated cats. However, this reflex responses could be unable to elicite in the spinal preparation. 3. The neurons responding exclusively to the ventral rami located in cranial parts of the nucleus and those responding to dorsal rami located in the caudal region. Neurons responding to both rami were also found.

Animals↗
PubMedDate not supplied

Flow volume in the common carotid artery detected by color duplex sonography: an approach to the normal value and predictability of cerebral blood flow.

PURPOSE: To determine normal common carotid artery (CCA) flow volume, its relationship with age, and the predictability of cerebral blood flow (CBF) by color duplex sonography. SUBJECTS AND METHODS: Forty-five healthy subjects (18 men, 27 women, 23-86 years old) and 13 patients (3 men, 10 women, 51-88 years old) without neurological disease underwent color duplex sonography. All 13 patients also underwent xenon CT. CCA flow volume in the healthy subjects was measured to determine normal values. This volume was divided by mean brain weight to estimate CBF, which was correlated with CBF measured by xenon CT in regions of ipsilateral internal carotid arteries (ICA). RESULTS: In healthy subjects, CCA flow volume ranged from 155.0-458.8 ml/min (mean+/-SD: 267.77+/-59.91), corresponding to an estimated CBF of 12.43-32.84 ml/min/100 g brain weight (mean+/-SD: 20.63+/-4.22). No relationship was found between flow volume and age. A good correlation was found between estimated CBF and CBF measured by xenon CT in regions of both ICAs (gamma=0.713, p=0.0062 on the left; gamma=0.686, p=0.0096 on the right). CONCLUSION: By using color duplex sonography, we established a set of normal CCA flow volumes, which do not decline with age. Estimated CBF derived from flow volume can predict actual CBF.

Adult↗