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Biomedical subjects

G Schlaug

Publications and source records attributed to G Schlaug.

At least 55 records · Page 3Linked to original sources
PubMed1996

Cerebellar hypometabolism in focal epilepsy is related to age of onset and drug intoxication.

PURPOSE: We wished to investigate the cerebellar depression of regional cerebral glucose metabolism (rCMRGlu) in patients with focal epilepsy. METHOD: In 170 consecutive patients with medically refractory, focal epilepsy the rCMRGlu was measured in cerebellum and brain. RESULTS: rCMRGlu was markedly decreased in both cerebellar hemispheres and slightly in brain. The cerebellum to brain rCMRGlu ratio was significantly decreased in patients with seizure manifestation in infancy, but was normal due to a progressive decrease in brain rCMRGlu in later age. A subgroup of patients with focal epilepsy involving the frontal lobe had a reduced cerebellum/brain rCMRGlu ratio, whereas in patients with mesiotemporal lobe epilepsy (MTLE), the rCMRGlu was decreased to the same degree in cerebellum and brain. The difference in the cerebellum/brain rCMRGlu ratio between the two groups was accounted for by the younger age of the patients with focal epilepsy involving the frontal lobe, however. In another subgroup of patients with a documented history of critical drug intoxications, the cerebellar rCMRGlu was severely decreased, resulting in a significantly reduced cerebellum/brain rCMRGlu ratio. CONCLUSION: Our retrospective study suggests that the cerebellum is particularly vulnerable in infancy to ongoing epileptic activity and high dosage of antiepileptic drugs (AEDs).

Adult↗
PubMed1996

Adult-onset complex partial seizures as the presenting sign in colpocephaly: MRI and PET correlates.

In a 30-year-old man, adult-onset complex partial seizures were associated with colpocephaly as evident from magnetic resonance images. The structurally normal lateral neocortex of the right temporal lobe showed a severe reduction in regional glucose consumption corresponding to the epileptic focus as judged from the surface electroencephalogram. In contrast to previously reported patients, this patient had no focal neurological signs, and neuropsychological testing revealed normal general intelligence. Thus, this patient adds a benign variant to the clinical spectrum of this cerebral developmental disorder.

Adult↗
PubMed1996

Topography of interictal glucose hypometabolism in unilateral mesiotemporal epilepsy.

We mapped the regional cerebral glucose metabolism (rCMRGlu) in 20 patients suffering from medically refractory focal epilepsy of either left or right mesiotemporal origin (mTLE) during resting wakefulness. After temporal lobectomy, histology demonstrated hippocampal sclerosis in 18 patients. Pixel-by-pixel comparisons with healthy control subjects showed significant (p < 0.001) depressions of the mean rCMRGlu ipsilateral to the epileptic focus in the mesiotemporal region, including the hippocampus and the parahippocampal gyrus and middle temporal gyrus. Additional remote rCMRGlu depressions occurred bilaterally in the fronto-orbital cortex and ipsilaterally in the posterior insula and the thalamus. Patients with left-sided mTLE had additional rCMRGlu depressions in the left inferior frontal gyrus (Broca's region) and superior temporal gyrus at the parietotemporal junction, whereas corresponding rCMRGlu depressions were not present in patients with right mTLE. Neuropsychological testing showed impaired verbal fluency, verbal intelligence, and verbal memory in the left mTLE patients. Correlations of the specific mean rCMRGlu depressions and the neuropsychological deficits suggest that impaired language functions in patients with left mTLE could result from functional changes beyond the temporal lobe.

Adolescent↗
PubMed1996

EEG-triggered echo-planar functional MRI in epilepsy.

We investigated whether: (1) EEG recordings could be successfully performed in an MRI imager, (2) subclinical epileptic discharges could be used to trigger ultrafast functional MRI images, (3) artifact-free functional MRI images could be obtained while the patient was having the EEG monitored, and (4) the functional MRI images so obtained would show focal signal increases in relation to epileptic discharges. We report our results in two patients who showed focally higher signal intensity, reflective of increased local blood flow, in ultrafast functional MRI timed to epileptic discharges recorded while the patients were in the imager and compared with images not associated with discharges. One patient showed a focal increase despite a clinical and EEG history of generalized discharges. This approach may have the potential to identify brain regions activated during brief focal epileptic discharges.

Adult↗
PubMed1995

Corpus callosum and brain volume in women and men.

Using high-resolution in vivo magnetic resonance morphometry we measured the midsagittal area of the corpus callosum and total forebrain volume in 120 healthy young adults (mean age (+/- s.d.) 25.7 +/- 4.7 years). The forebrain volume-adjusted size of the corpus callosum was larger in women than in men (32 mm2 mean difference; p = 0.011). Handedness had no effect in this measurement. The morphometric data confirm a gender difference in cerebral structural organization.

Adult↗
PubMed1995

In vivo evidence of structural brain asymmetry in musicians.

Certain human talents, such as musical ability, have been associated with left-right differences in brain structure and function. In vivo magnetic resonance morphometry of the brain in musicians was used to measure the anatomical asymmetry of the planum temporale, a brain area containing auditory association cortex and previously shown to be a marker of structural and functional asymmetry. Musicians with perfect pitch revealed stronger leftward planum temporale asymmetry than nonmusicians or musicians without perfect pitch. The results indicate that outstanding musical ability is associated with increased leftward asymmetry of cortex subserving music-related functions.

Adult↗
PubMed1995

Quantitative analysis of the columnar arrangement of neurons in the human cingulate cortex.

The spatial organization of human cingulate (areas 24b, 23b, and 31) and pericingulate (areas 7 and 19) cortex was examined by using an image analyzer to measure characteristics of vertically oriented, translaminar columns of neurons in the cerebral cortex. Columns of 30-50 microns in diameter are hypothesized to be a general feature of cortical organization, but no quantitative analysis of different human cortical areas has been performed. Our results prove for the first time that a columnar organization was detectable in every area examined. The average width of cell columns was approximately 40 microns separated by a neuropil-rich fascicle of the same dimension. Because differences in the expression of a columnar organization were seen, the degree of columnization was subsequently expressed by a verticality index (VI) revealing specific changes in its dimension depending on the architectonic area. The VI was calculated by a linear combination of three variables derived from the measurement of cell density profiles in Nissl-stained sections at right angles to vertically oriented cell columns. Variables included the amplitude of profile peaks, the standard deviation of the width of those profile peaks, and the standard deviation of the distances between profile peaks. The index of verticality describes the deviation of a distinct area and layer from the mean degree of vertical organization of all cortical areas and layers examined. Thus, different degrees of columnar organization can be quantitatively described by the verticality index and can be used as criteria to characterize architectonic areas.

Adult↗
PubMed1995

Epileptic seizures triggered directly by focal transcranial magnetic stimulation.

Focal, secondarily generalizing, epileptic seizures were released by magnetic stimulation in a patient with focal epilepsy. The stimulation induced seizures had a similar clinical appearance to the patient's spontaneous seizures. They were released exclusively by an angulated "figure-of-8" coil which stimulates the brain more focally as compared to the commonly used flat round coil. The epileptic focus could be located in the left frontal cortex by electroencephalographic recordings, by magnetic resonance and by positron emission tomography imaging. Functional assessment of the motor system by transcranial magnetic stimulation (TMS) disclosed markedly prolonged electrical silence of contralesional electromyographic activity following the early excitation. This is the first EMG-documented demonstration of a focal motor seizure directly triggered by magnetic brain stimulation.

Adolescent↗
PubMed1995

Increased corpus callosum size in musicians.

Using in-vivo magnetic resonance morphometry it was investigated whether the midsagittal area of the corpus callosum (CC) would differ between 30 professional musicians and 30 age-, sex- and handedness-matched controls. Our analyses revealed that the anterior half of the CC was significantly larger in musicians. This difference was due to the larger anterior CC in the subgroup of musicians who had begun musical training before the age of 7. Since anatomic studies have provided evidence for a positive correlation between midsagittal callosal size and the number of fibers crossing through the CC, these data indicate a difference in interhemispheric communication and possibly in hemispheric (a)symmetry of sensorimotor areas. Our results are also compatible with plastic changes of components of the CC during a maturation period within the first decade of human life, similar to those observed in animal studies.

Adult↗
PubMed1995

Subcortical origin of visuomotor apraxia.

Visuomotor apraxia (VMA) is a clinical syndrome characterized by a failure to make use of visual information when performing a target-directed movement. Visuomotor apraxia has traditionally been assumed to result from a disconnection of cortico-cortical fibres between visual and motor areas following occipito-parietal lesions. We describe a patient who developed a permanent contralesional and a temporary ipsilesional visuomotor apraxia as part of a complex neurological syndrome after a right [corrected] thalamic haemorrhage. MRI showed that the suprathalamic white matter was not involved but the most caudal fibres of the internal capsule appeared to be interrupted. To our knowledge this is the first case of a VMA with a lesion restricted to a deep subcortical area indicating that VMA can result from damage to subcortical projections rather than interruption of cortico-cortical fibres.

Aged↗
PubMed1995

Mapping of human and macaque sensorimotor areas by integrating architectonic, transmitter receptor, MRI and PET data.

The human and macaque sensorimotor cortex was subdivided into numerous areas by a correlative analysis based on cytoarchitectonics, myeloarchitecture and the distribution of transmitter receptors. Receptor densities and laminar distribution patterns differ not only between motor and somatosensory regions, but also between different areas within these regions of the cortex. Changes in receptor distribution often match architectonically defined borders. Receptor findings provide new criteria for a more detailed mapping in the human brain which cannot be achieved by cytoarchitectonic analysis alone. Morphological data on these areas were integrated with functional data from positron emission tomography (PET) on the basis of a recently developed computerised brain atlas. The central sulcus marks the border between (1) the agranular motor cortex with a generally low density of glutamatergic, muscarinic, GABAergic and serotoninergic receptors, and (2) the granular somatosensory cortex with higher densities of these receptors. Rostral to the primary motor cortex, 2 isocortical areas are found on the mesial cortex which probably represent the functionally defined supplementary motor areas (SMA) SMA-proper (caudally) and pre-SMA (rostrally). Below SMA-proper the areas 24d (macaque) and the caudal cingulate motor area cmc (human) are located in the cingulate sulcus. Both regions correspond to the 'posterior cingulate motor areas' of recent PET studies and to the posterior part of the agranular cingulate cortex of architectonic studies. Below pre-SMA the area 24c (macaque) and the rostral cingulate motor area cmr (human) are located in the cingulate sulcus; they correspond to the 'anterior cingulate motor areas' of recent PET observations and to the anterior part of the agranular cingulate cortex of architectonic studies. Homologous sensorimotor areas can be defined in both species on the basis of common architectonic features.

Animals↗
PubMed1994

Asymmetry of the planum parietale.

Using in vivo magnetic resonance morphometry we measured the posterior wall of the left and right posterior ascending portion of the Sylvian fissure, an inferior parietal area of the brain that we have termed the planum parietale. Among 106 right-handers (53 women and 53 men) and 35 left-handers (18 women and 17 men), handedness and gender exerted an interactive influence on planum parietale asymmetry; right-handed men and left-handed women showed particularly strong rightward asymmetry. There was no correlation between asymmetry of the planum parietale and that of the anatomically adjacent planum temporale, suggesting an independency of these two structural markers of brain laterality.

Adult↗
PubMed1994

Pharmacokinetics and radiation dose of oxygen-15 labelled butanol in rCBF studies in humans.

In this positron emission tomography (PET) study in humans we determined the pharmacokinetics and radiation dose of oxygen-15 labelled butanol, a recently introduced tracer for regional cerebral blood flow (rCBF). This report includes a description of the automated preparation of 15O-butanol which allows repetitive activation studies, each 15 min apart. Dynamic rCBF studies were extended by prolonged measurements up to 15 min after injection over different organs such as brain, liver, kidneys and bladder. All measurements were done with a whole-body PET camera PC4096-15WB. Based on the pharmacokinetic data in 13 subjects the radiation doses to single organs were calculated according to MIRD pamphlet No. 11 and the effective dose defined by ICRP 60 as an indicator of radiation dose to the total body. The liver received the highest radiation dose of about 2.2 mGy per 1500 MBq of injected 15O-butanol, which is the typical amount of administered tracer in one rCBF measurement. The dose to the kidneys was 1.6 mGy, to the stomach 0.8 mGy, and to the brain 0.16 mGy. The effective dose was 0.54 mGy, which was similar to that of H2(15)O, but lower than the effective dose from C15O2 in amounts typically applied in human rCBF studies.

Adult↗
PubMed1994

Inter-subject variability of cerebral activations in acquiring a motor skill: a study with positron emission tomography.

Cerebral structures activated during sequential right-hand finger movements were mapped with regional cerebral blood flow (rCBF) measurements by positron emission tomography (PET) in individual subjects. Nine healthy volunteers were examined twice; after initial learning and after practicing the finger movement sequence for more than 1 h. Task-specific activation sites were identified by statistical distributions of maximal activity and region size in rCBF subtraction images. A consistent task-specific activation in all nine subjects was detected in the contralateral sensorimotor cortex at an average movement rate of 3.2 Hz reached after practice. This corresponded to a significant increase of the mean rCBF in the left primary sensorimotor cortex in spatially standardised and averaged PET images. Additional task-specific activation sites detected by individual analysis were found in the lateral and medial premotor, parietal, and cingulate areas, and in subcortical structures including the basal ganglia of both cerebral hemispheres. These activations showed no or little spatial overlap from subject to subject, thus being obscured in the analysis of pooled data. The observed activity patterns were related to movement rate and accuracy in individual subjects. It is suggested that the rCBF changes associated with acquisition of a motor skill in individual humans may correspond to plasticity of sensorimotor representations reported in monkeys.

Adult↗
PubMed1994

Dopamine D2 receptor binding and cerebral glucose metabolism recover after D-penicillamine-therapy in Wilson's disease.

Regional cerebral glucose metabolism (rCMRGlc) and dopamine D2 receptor binding were measured in a 31-year-old, severely affected, untreated patient with Wilson's disease of 3 years' duration using positron emission tomography and 18F-deoxyglucose and 18F-methylspiperone ([18F]MSP), respectively. There was a severe reduction of striatal and extrastriatal rCMRGlc as well as of striatal [18F]MSP accumulation rate. After 1 year of treatment with D-penicillamine, striatal and extrastriatal rCMRGlc and striatal [18F]MSP accumulation rate reached almost normal levels. It is hypothesized that recovery of motor functions due to copper trapping therapy was associated with an increase in basal ganglia activity and a re-expression or upregulation of dopamine D2 receptors.

Adult↗