脑的不对称性影响大鼠局灶性脑缺血的结局

为评价左右侧大脑中动脉闭塞(MCAO)对右利大鼠神经行为功能和脑梗死体积的影响,本研究应用四足动物觅食实验筛选右利爪雄性SD大鼠24只,随机分为经左、右侧插线组各12只,8%水合氯醛腹腔注射(300mg/kg)麻醉,线栓法经左、右侧颈外-内动脉插入头端涂有多聚赖氨酸的4-0尼龙线,建立大鼠MCAO缺血2h模型,再灌注72h后评价动物的神经行为功能,测量脑梗死体积。结果表明,所有动物在脑缺血2h神经功能缺损评分最高,再灌注1、24、48和72h经左侧MCAO大鼠显著高于经右侧MCAO大鼠(P<0.05),后者功能明显优于前者,脑梗死体积经左侧插线的大鼠显著大于经右侧插线的大鼠(P<0.05)。研究结果提示,大鼠主侧半球大脑中动脉缺血后,神经功能缺损和脑梗死体积较对侧严重,脑的不对称性影响大鼠局灶性脑缺血的最终结局。     

Pathologic Reappraisal of Wallenberg Syndrome: A Pathologic Distribution Study and Analysis of Literature

Background

Wallenberg syndrome was first reported by Adolf Wallenberg as arising due to the obstruction of the posterior inferior cerebellar artery (PICA), which caused an infarct in the lateral medulla oblongata (MO).

Method

This study was carried out on brain tissue from 2 patients with typical Wallenberg syndrome and 10 autopsy cases without central nervous system disturbances.

Results

Patient 1 exhibited the 3 major neurological symptoms of right crossed sensory disturbance, right cerebellar ataxia and bulbar palsy. There was the pathological obstruction of the right vertebral artery (VA). Regarding the histopathlogical distribution, the infarct extended on the right side to the lateral spinothalamic tract, nucleus of the spinal tract of the trigeminal nerve, spinal tract of the trigeminal nerve, inferior cerebellar peduncle, spinocerebellar tract and nucleus ambiguous. Moreover, a clear infarct in the left lateral MO was pathologically identified, but pathological obstruction of the left PICA or left VA could not be found. The left cerebellar ataxia and bulbar palsy were observed among these 3 major symptoms. Patient 2 showed the 3 major symptoms of right crossed sensory disturbance, right cerebellar ataxia and bulbar palsy. A pathological luminal occlusion was identified in the right PICA. Regarding the histopathological lesion, the infarct disturbed on the right side the lateral spinothalamic tract, nucleus of the spinal tract of the trigeminal nerve, spinal tract of the trigeminal nerve, spinocerebellar tract, inferior cerebellar peduncle and nucleus ambiguus.

Conclusion

Based on our investigation of pathological lesions using our 2 autopsies, we suggest calling the cases that satisfy the following 3 criteria “definite pathologic Wallenberg syndrome”: i) identifiable pathological obstruction of the PICA or VA; ii) infarction in the lateral MO based on PICA or VA obstruction; and iii) a 1-to-1 correspondence between clinical symptoms and neuropathological lesions.     

Selective visual neglect in right brain damaged patients with splenial interhemispheric disconnection

Left unilateral neglect is frequently reported after right hemispheric lesions of the middle cerebral artery (MCA) damaging the parietal–frontal cortical–subcortical network subserving space representation and awareness. However, accumulating evidence shows that neglect can also follow lesions of the posterior cerebral artery (PCA) that do not directly affect this parietal–frontal network. Surgical studies in the monkeys have demonstrated that complete callosal resection combined with lesion of the right optic tract entirely deprives the right hemisphere of visual inputs from the left hemispace provoking severe left unilateral neglect. Here, through the detailed study of two patients we show, for the first time, that PCA lesions selectively affecting the splenium of the corpus callosum and the adjacent right primary visual cortex provoke severe neglect selectively restricted to the visual domain. No trace of personal, motor or representational-imagery neglect was found. Also at variance with previous case studies in which neglect followed lesion of the trunk or the genu of the corpus callosum, no restriction of neglect to tasks performed with the right hand, no left hemispatial limb akinesia, no tactile extinction for the left hand and no tactile anomia for stimuli explored with the left hand were observed. These findings demonstrate that brain lesions depriving intact parietal and frontal attentional areas from specific sensory inputs can yield spatial neglect limited to specific sensory modalities or sectors of space.     

Corticospinal tract compression by hematoma in a patient with intracerebral hemorrhage: a diffusion tensor tractography and functional MRI study

The purpose of this study was to demonstrate corticospinal tract compression that was due to a hematoma by using diffusion tensor tractography (DTT) and functional MRI (fMRI) in a patient with an intracerebral hemorrhage (ICH). A 23-year-old right-handed woman presented with severe paralysis of her right extremities at the onset of a spontaneous ICH. Over the first three days from onset, the motor function of the affected upper and lower extremities rapidly recovered to the extent that she was able to overcome applied resistance to the affected limbs, and her limbs regained normal function 3 weeks after onset. The tract of the right hemisphere originated from the primary sensori-motor cortex (SM1) and it passed through the known corticospinal tract pathway. However, the tract of the left hemisphere was similar to that of the right hemisphere except that it was displaced to the antero-medial side by the hematoma at the cerebral peduncle. Only the contralateral SM1 area centered on the precentral knob was activated during affected (right) or unaffected (left) hand movements, respectively. In conclusion, fMRI and DTT demonstrated a corticospinal tract compression due to hematoma in this patient. We conclude that the combined use of these two modalities appears to improve the accuracy of investigating the state of the corticospinal tract.     

CRT screens may give rise to biased estimates of interhemispheric transmission time in the Poffenberger paradigm

It has been shown that computer video-display units do not emit luminance uniformly over the entire screen, but emit more light on the right hand side than on the left hand side. The present study investigates whether this luminance asymmetry has implications for the manual and vocal estimates of interhemispheric transmission time (IHTT) in the Poffenberger paradigm. In particular, it is shown that previous reports of right visual-field advantages for vocal responses are an artifact of the luminance asymmetry of computer screens and that this asymmetry also has implications for estimates of differences in transmission time from the right to the left hemisphere in manual responses. In addition, we examined the impact of stimulus intensity and dark adaptation to the IHTT estimates and found that neither had an effect. This is in line with previous evidence that interhemispheric transfer in the Poffenberger paradigm does not depend on the transfer of visual information.     

Monocular-unihemispheric sleep and visual discrimination learning in the domestic chick

During sleep, domestic chicks (Gallus gallus) show brief and transient periods during which one eye is open while the other remains shut. Electrophysiological recordings showed that the hemisphere contra-lateral to the open eye exhibited an EEG with fast waves typical of wakefulness, whereas the hemisphere contra-lateral to the closed eye exhibited an EEG typical of slow wave sleep. We investigated the pattern of monocular-unihemispheric sleep (Mo-Un sleep; i.e. selective preferential closure/opening of the left or right eye during sleep) following three types of visual learning tasks. The first group of chicks was submitted to a colour discrimination task (1), the second group to a spatial discrimination task with colour as a conspicuous, but irrelevant, cue (2), the third group to a spatial task without colour cue. After learning, the amount of binocular sleep and Mo-Un sleep patterns were recorded. The first and the second group of chicks exhibited more right Mo-Un sleep (right eye-closure/left unihemispheric sleep), suggesting that this pattern may be connected with prevalent engagement of left hemisphere during training trials. The third group showed a significant more left Mo-Un sleep (left eye-closure/right unihemispheric sleep) which would be associated with a prevalent engagement of right hemisphere during trials. Chicks of the control groups, did not learn the task, but were submitted to an equal number of trials. Controls of tasks 1 and 2 showed more left Mo-Un sleep suggesting a dominance of right hemisphere during exposure trials. Instead there was no eye-closure bias in controls of task 3, suggesting an absence of hemispheric dominance during trials. It is suggested that the Mo-Un sleep pattern may be a type of local sleep associated with a process of functional recovery in the hemisphere which was mainly engaged during training trials.     

Athabascan brainstem dysgenesis syndrome

We report a new disorder with diverse neurological problems resulting from abnormal brainstem function. Consistent features of this disorder, which we propose should be called the Atabascan brainstem dysgenesis syndrome, include horizontal gaze palsy, sensorineural deafness, central hypoventilation, and developmental delay. Other features seen in some patients include swallowing dysfunction, vocal cord paralysis, facial paresis, seizures, and cardiac outflow tract anomalies. All affected children described are of Athabascan Indian heritage, with eight children from the Navajo tribe and two patients who are of Apache background. The disorder can be distinguished from the Moebius syndrome by the pattern of central nervous system findings, especially the sensorineural deafness, horizontal gaze palsy, and central hypoventilation. Recognition of children with some features of Athabascan brainstem dysgenesis syndrome should prompt investigation for other related abnormalities. Published 2003 Wiley-Liss, Inc.     

Cerebral blood flow in essential hypotension during emotional activation

Variations of blood flow velocity in the left and right middle cerebral arteries (MCA) were measured in 20 hypotensive women and 20 normotensive control subjects during emotional stimulation using functional transcranial Doppler sonography (fTDS). The emotional stimuli were composed of three series (neutral, pleasant, and unpleasant) of 20 pictures from the International Affective Picture System (IAPS). Both groups exhibited greater increases in right than left MCA blood flow during emotional stimulation. However hypotensive subjects showed smaller increases in blood flow than did normotensive controls. Furthermore hypotensives exhibited lower MCA blood flow velocity in both hemispheres at rest than did normotensives. Nevertheless the hypotensive group rated the emotional pictures as more arousing than did the control group. Results suggest a decreased blood flow, in addition to peripheral, in the central nervous system (CNS) of hypotensives, which was associated with normal emotional responses for both valence and hemispherical asymmetry, but also with a general increase of arousal levels. This dissociation might be related to an increase in anterior cerebral arteries (ACA) blood flow and/or to hypotension-mediated baroreceptors' up-regulation to the reticular system.     

Failure to control prepotent pathways in early stage dementia of the Alzheimer's type: evidence from dichotic listening

The authors examined the right ear advantage in a dichotic listening task in healthy aging and very mild and mild stages of Alzheimer's disease. Subjects were simultaneously presented 3 pairs of digits to the left and right ears (e.g., left ear: 4, 3, 1; right ear: 9, 2, 5) for immediate ordered recall. Four lists of triads were presented, varying in presentation rate between digit pairs within a triad (0.5, 1.0, 1.5, 2.0 s). Results indicated that the very mild and mild Alzheimer's groups showed a larger right ear advantage in free recall compared with the healthy controls, indicating a tendency to respond to the prepotent left hemisphere pathway for language processing. Also, the right ear advantage and proportion of switches made during recall were correlated with psychometric measures of frontal lobe function in the mild Alzheimer's group but not in the very mild or healthy control groups.     

Actinomycosis of the vocal cord: a case report

A 30-year-old Chinese lady was admitted for hoarseness of voice of one month's duration. Clinical examination revealed a granuloma of the left vocal cord while chest X-ray showed an opacity in the lower lobe of the right lung. The provisional clinical diagnosis was tuberculous laryngitis. A biopsy of the vocal cord lesion revealed inflamed tissue with actinomycotic colonies. Cultures and sputum smears did not reveal any tuberculous bacilli. The patient responded to a 6-week course of intravenous C-penicillin, regaining her voice on day 5 of commencement of antibiotics. A subsequent CT scan of the neck and thorax revealed multiple non-cavitating nodular lesions in both lung fields, felt to be indicative of resolving actinomycosis. She was discharged well after completion of treatment. It was felt that this is a case of primary actinomycosis of the vocal cord with probably secondary pulmonary actinomycosis.     

Right but not left angular gyrus modulates the metric component of the mental body representation: a tDCS study

The parietal lobes contribute to body-space representation. The present work aims at characterizing the functional role of the inferior parietal lobe in body-space representation and at studying the different roles of the angular gyrus in the right and left hemisphere. We conducted three separate transcranial direct current stimulation (tDCS) experiments using “tactile distance task” as an implicit measure of body representation. Whereas anodal tDCS on the right angular gyrus influences vocal reaction times (vRT) for stimuli delivered on the ipsilateral body parts without changes of accuracy, right tDCS improved both vRT and accuracy for tactile stimuli on the contralateral limbs. Sham or left parietal anodal tDCS had no effect. These evidences support the view that right parietal areas have a crucial role in the metric component of the body representation.     

Diameter and length changes in cerebral collaterals after middle cerebral artery occlusion in the young rat

Rapid occlusion of the middle cerebral artery (MCA) in the 36-day-old normal Wistar rat results in change of the dorsal collaterals joining branches of the anterior and middle cerebral arteries. As compared to similarly positioned vessels on the opposite hemisphere and arterioles in unoperated rats of 56 days, of age, there were significantly (P < 0.001) more large (60–120 μm)diameter collaterals on the occluded side 20 days after MCA occlusion. There were fewer small (0-59μm) diameter collaterals on the occluded side as compared to unoperated rats. The data suggest small diameter arterioles existing at occlusion became large diameter collaterals. The mean number of collaterals per hemisphere was not significantly different (P > 0.05) between occluded and unoperated rats. There was no evidence that new vessels were added during the 20-day ligation period. The mean collateral tortuosity value was significantly (P < 0.01) greater for large diameter vessels on the right occluded side as compared to vessels on the left hemisphere or vessels in unoperated age-matched control rats. The greater tortuosity values of vessels on the occluded side were evidence that collateral vessel length was increased by 24–29% after MCA occlusion. Speculation was made about possible mechanisms responsible for these vascular changes.     

Three patterns of brain damage of the WAIS.

Compared four groups of matched Ss (40 each) in order to examine different subtest patterns of brain damage on the WAIS, using F-tests and age mean profiles. The groups were: Normals, diffuse cortical degeneration, right and left hemisphere damage. The results indicated three patterns: (1) a normal pattern; (2) a diffuse degenerative and right hemisphere pattern; and (3) a left hemisphere pattern. The diffuse degenerative results were not significantly different from the right hemisphere results. The left hemisphere pattern had no large verbal vs. performance differences. These patterns appear to be produced by the interaction of three brain damage effects: (1) a general effect; (2) a right hemisphere effect; and (3) a left hemisphere effect. Verbal tests are both "hold" and left hemisphere tests, while three Performance Tests are "don't hold" and right hemisphere tests. The WAIS requires other specific tests of brain damage for an adequate assessment of brain damage.     

Dorsal cerebral arterial collaterals of the rat

This study demonstrated that distal branches of the anterior cerebral artery (ACA) are joined by interarterial anastomoses to rami of the middle cerebral artery (MCA) in the normal Wistar rat. Arteries of 36- and 56-day-old animals were dilated with papaverine and injected with Vultex. Vultex arrived at corresponding ACA and MCA collaterals simultaneously as determined by microscopy through a skull window and photography. There were about 29 ACAMCA junctions per hemisphere. Junction density was nearly constant along the frontal-occipital axis. The anastomoses were most numerous between 2 and 3 mm lateral to the midline and were less than 120 μm in internal diameter. No significant difference was found between total numbers of junctions for right versus left hemispheres or between age groups. The most evident collateral pattern was characterized by two ACA end rami joining two MCA end branches to form a closed, diamond-shaped collateral unit. Considerations were given to alternate routes of blood flow into the MCA tissue field. We conclude abundant dorsal anastomoses exist in 36- and 56-day-old rats and are the prime potential source for ACA collateral supply to the MCA tissue field.     

Hypnotic susceptibility: a lateral predisposition and altered cerebral asymmetry under hypnosis

Psychophysiological and behavioural evidence is reported of altered cerebral asymmetry under hypnosis in favour of the right hemisphere. This occurred in Susceptible as distinct from Unsusceptible subjects. Measures included bilateral electrodermal responses to tones and bimanual processing times for sorting letters and numbers with eyes closed. Subjects listened to a tape recording of a procedure for inducing relaxation under hypnosis. Susceptible subjects, unlike Unsusceptibles, showed lateral asymmetries in baseline conditions in favour of the left hemisphere. Electrodermal responses were larger on the left than the right hand and haptic processing times were faster with the right than the left hand. Under hypnosis there was a reduction in electrodermal orienting responses coupled with faster habituation and a reversal in lateral asymmetries. Haptic processing revealed a slowing in right hand processing times whereas left hand times were reduced as was the case with bilateral processing times in both Unsusceptible subjects and controls who experienced no hypnosis. Unlike earlier reports left hemisphere dynamic processes were fundamental to the induction of hypnosis. A neuropsychological model is proposed whereby susceptibility is associated both with a left bias prior to hypnosis and left hemisphere inhibition under hypnosis. Unsusceptibles retain a right hemisphere orientation without undergoing left hemisphere inhibition. Thus hypnosis involves an inhibition of left-sided processes which permits the ascendancy of the right hemisphere through the attenuation of left hemisphere control.     

Vocal cord abnormalities in Williams syndrome: a further manifestation of elastin deficiency

Williams syndrome (WS) is due to a deletion in the WS critical region at 7q11.23 which includes the elastin gene (ELN). One of the most characteristic features of this disorder is a harsh, brassy, or hoarse voice but the etiology of the vocal characteristics are unknown. We report two patients with WS who had bilateral vocal cord abnormalities, bringing to four the number of children with WS in whom such defects have been documented. We suggest that vocal cord abnormalities may be a far more common feature of WS than has been previously suspected, and that mild vocal cord dysfunction caused by abnormal vocal cord elastin may be the cause of the hoarse voice in this condition.     

Tc-99m-ECD SPECT brain imaging in children with Tourette's syndrome

We undertook this study to assess the patterns of regional cerebral perfusion (RCP) with SPECT using Technetium- 99m-ethyl cysteinate dimer (Tc-99m-ECD) in children with Tourette's Syndrome (TS), and to compare these with the patterns in a group of normal controls. The study sample consisted of 38 children (7 to 14 years) who met the ICD-10 and DSM/IV criteria for Tourette's Syndrome, and a control group of 18 children (9 to 14 years). The Children's Depression Inventory and Maudsley Obsessional-Compulsive Questionnaire were used for assessment, and the severity of motor and vocal tics were assessed using the Goetz Rating Scale. The RCP values were significantly lower in the TS group in left caudate, cingulum, right cerebellum, left dorsolateral prefrontal, and the left orbital frontal region. A positive correlation was found between the severity of vocal tics and blood flow of mid-cerebellum, right dorsolateral prefrontal and left dorsolateral prefrontal regions. Although no depressive or obsessive patients were included in the study, the depression and obsession scores were found to be negatively correlated with all RCP values, especially in the temporal regions. Further studies are needed to explore the relationship between the hypoperfusion of certain brain areas and the underlying neurophysiology and neurobiology of patients with TS. Additional disturbances such as obsessive-compulsive symptoms and depressive symptoms should also be assessed     

The left visual-field advantage in rapid visual presentation is amplified rather than reduced by posterior-parietal rTMS

In the present task, series of visual stimuli are rapidly presented left and right, containing two target stimuli, T1 and T2. In previous studies, T2 was better identified in the left than in the right visual field. This advantage of the left visual field might reflect dominance exerted by the right over the left hemisphere. If so, then repetitive transcranial magnetic stimulation (rTMS) to the right parietal cortex might release the left hemisphere from right-hemispheric control, thereby improving T2 identification in the right visual field. Alternatively or additionally, the asymmetry in T2 identification might reflect capacity limitations of the left hemisphere, which might be aggravated by rTMS to the left parietal cortex. Therefore, rTMS pulses were applied during each trial, beginning simultaneously with T1 presentation. rTMS was directed either to P4 or to P3 (right or left parietal cortex) either as effective or as sham stimulation. In two experiments, either one of these two factors, hemisphere and effectiveness of rTMS, was varied within or between participants. Again, T2 was much better identified in the left than in the right visual field. This advantage of the left visual field was indeed modified by rTMS, being further increased by rTMS to the left hemisphere rather than being reduced by rTMS to the right. It may be concluded that superiority of the right hemisphere in this task implies that this hemisphere is less irritable by external interference than the left hemisphere.     

Mental rotation performance: Age,sex, and visual field differences

Eighteen young (17–23 years) and 18 older (66–79 years) adults performed a mental rotation task under lateralized viewing conditions to compare the generalized versus right hemisphere decline hypothesis of neuropsychological aging. Although older adults exhibited slower reaction times and less accuracy than younger adults, visual field patterns were independent of age and sex. There was no evidence to indicate a selective decline with age in left hemisphere or right hemisphere processing ability during mental rotation performance. These results support the hypothesis that hemispheric changes in processing with age are not selective but are generalized across both hemispheres.