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Andreas Straube

Publications and source records attributed to Andreas Straube.

31 records · Page 2Linked to original sources
PubMed2003

Unilateral cerebellar lesions influence arm movements bilaterally.

Limb ataxia is seen as a sign of ipsilateral cerebellar dysfunction. However, imaging studies have shown a bilateral cerebellar activation during unilateral hand movements. We questioned whether unilateral cerebellar lesions affect pointing movements not only of the ipsilateral hand but also of the contralateral hand. Horizontal saccadic pointing movements of 10 patients with unilateral cerebellar infarctions (infarctions of the posterior inferior or superior cerebellar artery) were compared with those of 19 controls. The movements were recorded with an infrared video motion analysis system. The peak velocity, time lag, and dysmetria of the ipsilateral and contralateral hands were calculated. Patients with cerebellar infarctions had significantly slower movements not only for the ipsilateral but also for the contralateral arm. The time lag of these movements in patients was also significantly larger for both arms. In contrast, there was no significant difference in dysmetria at the endpoints. These findings indicate that both ipsilateral and contra-lateral movements of patients with unilateral cerebellar lesions are slightly impaired.

Adult↗
PubMed2003

Haptic texture affects the kinematics of pointing movements, but not of eye movements.

Discrepant findings on the degree of eye-hand coupling suggest its dependence on the task. One task characteristic modulating this coupling may be the relevance of certain target attributes for each motor system. We tested this assumption by comparing eye and hand movements towards targets of different haptic texture, a target attribute which is behaviourally relevant only to the hand, not the eye. Pointing to a slippery target (fur) resulted in longer hand movement time than to a rougher target (sandpaper). This effect was due to an increased ratio of time spent in deceleration. In contrast, eye movement time was invariant across different haptic target textures. Thus, information about target texture is used differently by eye and hand.

Adult↗
PubMed2003

Predictive pointing movements and saccades toward a moving target.

The authors investigated whether and, if so, how velocity information is used to control predictive manual pointing movements and saccades. Participants (N = 6) intercepted an occluded moving target as if it were still visible. They kept their eyes fixated while the target moved. The target traveled over a fixed distance and changed its velocity on the way. The presentation time of the final velocity was varied. Both the eye and the hand overshot the slow target and undershot the fast target, particularly when the duration of the final velocity was short. Thus, responses were biased in the direction of the target's initial velocity. The error seemed to arise because participants did not take their latency into account when aiming at the target. Instead, they strategically aimed farther ahead when the target was fast. Amplitude was also more related to the position of velocity change than to final velocity duration. Both findings suggest that target velocity is not extrapolated but that individuals add an increment to the position of velocity change.

Adult↗
PubMed2003

Expression of neuronal markers in differentiated marrow stromal cells and CD133+ stem-like cells.

Bone marrow stromal cells, which normally give rise to bone, cartilage, adipose tissue, and hematopoiesis-supporting cells, have been shown to differentiate in vitro and in vivo into neural-like cells. In this study, we examined the expression of neuronal and glial markers in human marrow stromal cells under culture conditions appropriate for neural stem cells, and compared the unsorted cell population to bone marrow CD133+ stem-like cells using immunofluorescence, Western blot, and functional patch-clamp analysis. Overall, the expression of the early neuronal marker beta3-tubulin was most pronounced in the presence of DMEM/F12 and neurotrophin 3 (NT3) or brain-derived neurotrophic factor (BDNF), when marrow stromal cells were cultured onto fibronectin. Electrophysiological examination, however, could not show fast sodium currents or functional neurotransmitter receptors in differentiated marrow stromal cells. CD133+ mesenchymal stem-like cells, but not CD34+/CD133- cells, generally showed a higher expression of neuronal markers than did unsorted marrow stromal cells, and differentiated CD133+ cells more resembled neuron-like cells.

AC133 Antigen↗
PubMed2002

Modeling visuospatial perception in neglect patients.

The spatial distortion hypothesis is one of several theories that explain certain aspects of neglect in patients with right parietal lesions. To determine whether a distorted representation of space can account for the performance of neglect patients in different visuospatial tasks, we asked 26 neglect patients to: (1) bisect horizontal lines and (2) to compare the width of two horizontally aligned bars. A simple mathematical model compatible with the idea of a stationary distortion of represented space in egocentric coordinates explained the results of the line-bisection task. A second model that had basically the same structure and was compatible with the idea of a distorted egocentric representation based on a dynamic remapping of space approximated the size-comparison data. These results support the view that abnormalities observed in the line-bisection and size-comparison tasks are due to a distorted internal representation of the external world. Certain findings suggest that this distortion could be based on a dynamic mapping of space determined by the distribution of visuospatial attention.

Adult↗
PubMed2002

Implications of distracter effects for the organization of eye movements, hand movements, and perception.

The end positions of eye and hand movements were both drawn towards a distracter that was presented nearby the target. They thus showed a so-called global effect. In contrast, perception was not influenced by the presence of a distracter. These results are discussed with regard to the question whether eye, hand, and perception are based on shared or separate target representations and readout triggers. We conclude that separate representations and readout triggers for eye and hand are the most likely case.

Eye Movements↗
PubMed2002

Comorbidity of Tourette's syndrome and schizophrenia--biological and physiological parallels.

The authors report on five patients who first developed Tourette's syndrome (TS) and later schizophrenia with the typical positive and negative symptoms; all five had an unfavorable course of schizophrenia. These observations as well as other reported cases raise the question of whether both disorders may share a common background. This is discussed under the aspects of similar symptomatology (echolalia, motor symptoms, cognitive deficits, obsessive-compulsive symptoms), similar pathophysiological signs, genetics and signs of an underlying inflammatory process in subgroups of cases, as well as common therapeutic strategies. A genetically determined susceptibility could possibly underlie both disorders, e.g., an autoimmunologically triggered inflammation or a common pathophysiology of certain symptoms. Both disorders show disturbances of the multiple functional pathways, which seem to be involved in the pathophysiology of both. The clinical overlap of TS and of schizophrenia may be due to a final common pathophysiological pathway.

Adult↗
PubMed2002

Diffusion-weighted magnetic resonance imaging during the aura of pseudomigraine with temporary neurologic symptoms and lymphocytic pleocytosis.

A typical feature of pseudomigraine with temporary neurologic symptoms and lymphocytic pleocytosis (PMP) is the long duration of aura symptoms. To determine if these prolonged auras cause early ischemic parenchymal changes, we performed diffusion-weighted magnetic resonance imaging during the aura of a patient with PMP and found no reduction of water diffusion.

Adult↗
PubMed2002

Global effect of a nearby distractor on targeting eye and hand movements.

Eye-hand coordination was investigated with the global effect paradigm. In this paradigm, saccades typically land in between the target and a nearby presented distractor, the configuration's center of gravity. This so-called global effect, or spatial averaging, is attributed to incomplete target selection. Four experiments demonstrated a similar effect for hand movements; thus, eye and hand are coupled during target selection. However, under some conditions the global effect was different for eye and hand, suggesting that their coupling is not achieved through a shared target representation. Instead, eye and hand seem to use 2 separate target representations that exchange information. The convergent amplitudes of eye and hand with simultaneous execution support this interpretation. Latencies showed a similar converging pattern.

Adult↗
PubMedDate not supplied

A fatal encephalitis.

Explore the source record for details and available documents.

Encephalitis, Viral↗
PubMedDate not supplied

Headache associated with epileptic seizures: epidemiology and clinical characteristics.

OBJECTIVE: To investigate the incidence and characteristics of seizure-associated headaches and the modalities of treatment. BACKGROUND: Systematic investigations of the characteristics of seizure-associated headaches are rare. Although data in the literature on the incidence of postictal headaches range between 37% and 51%, experiences with their treatment are limited and pathophysiological concepts do not exist. METHODS: One hundred ten epileptic outpatients from an epilepsy referral center participated in a semi-standardized interview about headaches associated with epileptic seizures. The characteristics of these patients and of 15 additionally recruited patients with known postictal headaches were analyzed. RESULTS: The incidence of seizure-associated headaches was 43% (n = 47). Forty-three patients had exclusively postictal headaches. One patient had exclusively preictal headaches. Three patients had both pre- and postictal headaches. The duration of postictal headaches was longer than 4 hours in 62.5% of the patients. In the majority of patients, postictal headaches occurred in more than 50% of the seizures. Postictal headaches were treated by self-medication in 19 patients (30%). No patient treated headaches according to a medical prescription. In 11 patients, postictal migraine was untreated. Postictal headaches were associated with focal seizures in 23 patients and/or with generalized seizures in 54 patients. According to the headache classification of the International Headache Society, headaches were classified as migraine-type in 34% of patients and as tension-type headache in 34% of patients. Headaches could not be classified in 21% of patients. Patients with and without postictal headaches did not differ as to localization of the epileptogenic zone or to the number of prescribed antiepileptic drugs. There was no relationship between the localization of the epileptogenic focus, localization of the headache, or the headache classification. CONCLUSIONS: Headaches associated with partial and generalized seizures are frequent and undertreated. Treatment should consider both the headache syndrome and the general guidelines for treating primary headaches. The pathophysiology of seizure-associated headaches cannot be explained by the epileptic syndrome.

Adult↗