Biomedical subjects

Brigitte Rockstroh

Publications and source records attributed to Brigitte Rockstroh.

11 recordsLinked to original sources

PubMed2003

Source distribution of neuromagnetic slow-wave activity in schizophrenic patients--effects of activation.

When slow waves in the EEG delta and theta frequency range appear in the waking state, they may indicate pathological conditions including psychopathology. The generators of focal slow waves can be mapped using magnetic source imaging. The resulting brain maps may possibly characterize dysfunctional brain areas. The present study examined the stability of the density and distribution of MEG slow waves during three conditions-rest, mental arithmetic and imagery-in 30 schizophrenic patients and 17 healthy controls. Schizophrenic patients displayed a higher density of delta and theta generators primarily in temporal and parietal areas. The group difference was not affected by the particular conditions. The focal concentration of delta and theta slow waves did not differ between patients with and without neuroleptic medication, whereas the prominence of theta dipoles in the temporal area correlated with neuroleptic dosage. The relative amount of temporal slow waves was correlated with the negative symptoms score (PANSS-N) suggesting that temporal dysfunction may be related to negative symptomatology.Results suggest that the distribution of slow-wave activity, measured in a standardized setting, might add diagnostic information about brain abnormalities in schizophrenia.

Adult↗

PubMed2003

Effective behavioral treatment of focal hand dystonia in musicians alters somatosensory cortical organization.

New perspectives in neurorehabilitation suggest that behavioral treatments of movement disorders may modify the functional organization of central somatosensory neural networks. On the basis of the assumption that use-dependent reorganization in these networks contributes to the fundamental abnormalities seen in focal dystonia, we treated 10 affected musicians and measured the concomitant somatosensory changes by using whole-head magnetoencephalography. We found that effective treatment, using the method of sensory motor retuning, leads to alterations in the functional organization of the somatosensory cortex. Specifically, before treatment, somatosensory relationships of the individual fingers differ between the affected and unaffected hands, whereas after treatment, finger representations contralateral to the dystonic side become more similar to the less-affected side. Further, somatosensory finger representations are ordered more according to homuncular principles after treatment. In addition, the observed physiologic changes correlated with behavioral data. These results confirm that plastic changes in parallel with emergent neurological dysfunction may be reversed by context-specific, intensive training-based remediation.

Behavior Therapy↗

PubMed2003

Semantic categorization in the human brain: spatiotemporal dynamics revealed by magnetoencephalography.

We examined the cortical representation of semantic categorization using magnetic source imaging in a task that revealed both dissociations among superordinate categories and associations among different base-level concepts within these categories. Around 200 ms after stimulus onset, the spatiotemporal correlation of brain activity elicited by base-level concepts was greater within than across superordinate categories in the right temporal lobe. Unsupervised clustering of data showed similar categorization between 210 and 450 ms mainly in the left hemisphere. This pattern suggests that well-defined semantic categories are represented in spatially distinct, macroscopically separable neural networks, independent of physical stimulus properties. In contrast, a broader, task-required categorization (natural/man-made) was not evident in our data. The perceptual dynamics of the categorization process is initially evident in the extrastriate areas of the right hemisphere; this activation is followed by higher-level activity along the ventral processing stream, implicating primarily the left temporal lobe.

Adult↗

PubMed2002

Expansion of the tonotopic area in the auditory cortex of the blind.

A part of the core area of the auditory cortex was examined in nine blind and 10 sighted individuals by magnetic source imaging and was found to be enlarged by a factor of 1.8 in the blind compared with the sighted humans. Moreover, the latency of the N1m component of the auditory-evoked magnetic response was significantly decreased in the blind. The development of use-dependent cortical reorganization may be a consequence of the absence of visual input in combination with enhanced auditory activity generated by the long-term concentration by blind individuals on nonvisual cues to interact appropriately with the environment. It is consistent with and well suited to mediate the demonstrated increased ability of the blind to accurately localize acoustic sources in peripheral auditory fields and to decode speech.

Acoustic Stimulation↗

PubMed2002

Focal temporoparietal slow activity in Alzheimer's disease revealed by magnetoencephalography.

BACKGROUND: Patients suffering from Alzheimer's disease exhibit more activity in the conventional electroencephalographic delta and theta bands. This activity concurs with atrophy and reduced metabolic and perfusion rates, particularly in temporoparietal structures. METHODS: Whole-head magnetoencephalographic recordings were obtained from 15 patients diagnosed with Alzheimer's disease and 19 healthy control subjects during a resting condition. The generators of focal magnetic slow waves were located employing a single moving dipole model. RESULTS: Dipole density in the delta and theta bands was enhanced in the Alzheimer's disease group compared with healthy control subjects. Slow-wave activity differed significantly between groups in temporoparietal regions of both hemispheres. Right temporoparietal slow-wave activity covaried with cognitive performance, whereas left temporal delta activity varied with a functional status scale. CONCLUSIONS: Our results support the predominant role of the temporoparietal areas in the diagnosis of Alzheimer's disease. Magnetoencephalography and the source analysis of focal slow activity in particular provide interesting and potentially clinically useful tools to assess functional modifications of patients' brain and to evaluate its relationship with the cognitive status.

Aged↗

PubMed2002

Reduced interhemispheric transmission in schizophrenia patients: evidence from event-related potentials.

Interhemispheric transfer was investigated in 14 schizophrenia patients and 15 age- and sex-matched healthy controls in a lateralized lexical decision task. Words and pseudowords were tachistoscopically presented either to the left or to the right visual hemifield. Event-related potentials were determined from a 65-channel electroencephalogram. Information transfer between hemispheres was assessed by the interhemispheric transmission time (IHTT), the N1-latency difference between ipsilateral and contralateral hemisphere.Controls, but not schizophrenia patients showed significantly faster IHTT from the right to the left hemisphere for words, while IHTT from the left to the right hemisphere did not differ between groups and stimuli. These findings are interpreted in terms of a deficit in schizophrenia to transfer verbal information from the right to the left hemisphere via the corpus callosum.

Adult↗

PubMed2002

Large-scale neural correlates of affective picture processing.

Hemodynamic and electrophysiological studies indicate differential brain response to emotionally arousing, compared to neutral, pictures. The time course and source distribution of electrocortical potentials in response to emotional stimuli, using a high-density electrode (129-sensor) array were examined here. Event-related potentials (ERPs) were recorded while participants viewed pleasant, neutral, and unpleasant pictures. ERP voltages were examined in six time intervals, roughly corresponding to P1, N1, early P3, late P3 and a slow wave window. Differential activity was found for emotional, compared to neutral, pictures at both of the P3 intervals, as well as enhancement of later posterior positivity. Source space projection was performed using a minimum norm procedure that estimates the source currents generating the extracranially measured electrical gradient. Sources of slow wave modulation were located in occipital and posterior parietal cortex, with a right-hemispheric dominance.

Adult↗

PubMed2002

Brain activity during syntactic and semantic processing--a magnetoencephalographic study.

Drawings of objects were presented in series of 54 each to 14 German speaking subjects with the tasks to indicate by button presses a) whether the grammatical gender of an object name was masculine ("der") or feminine ("die") and b) whether the depicted object was man-made or nature-made. The magnetoencephalogram (MEG) was recorded with a whole-head neuromagnetometer and task-specific patterns of brain activity were determined in the source space (Minimum Norm Estimates, MNE). A left-temporal focus of activity 150-275 ms after stimulus onset in the gender decision compared to the semantic classification task was discussed as indicating the retrieval of syntactic information, while a more expanded left hemispheric activity in the gender relative to the semantic task 300-625 ms after stimulus onset was discussed as indicating phonological encoding. A predominance of activity in the semantic task was observed over right fronto-central region 150-225 ms after stimulus-onset, suggesting that semantic and syntactic processes are prominent in this stage of lexical selection.

Adult↗

PubMed2002

Sensory motor retuning: a behavioral treatment for focal hand dystonia of pianists and guitarists.

OBJECTIVE: To evaluate the long-term effectiveness of sensory motor retuning (SMR), a new treatment for focal hand dystonia in musicians. DESIGN: Prospective case series with an (adventitious) comparison group with 3- to 25-month follow-up in piano and guitar and 0- to 4-month follow-up in flute and oboe players. SETTING: General community in Germany. PARTICIPANTS: Eleven professional musicians. INTERVENTION: Immobilization by splints of 1 or more digits other than the focal dystonic finger. This finger carried out repetitive exercises in coordination with 1 or more of the other digits for 1(1/2) to 2(1/2) hours a day for 8 consecutive days under therapist supervision. The subjects then were instructed to continue practice for 1 hour daily for 1 year. MAIN OUTCOME MEASURES: Spectral analysis of the output of a dexterity-displacement device that continuously recorded digital displacement during finger movements and a dystonia evaluation scale on which patients rated how well they had just performed dystonic movement sequences and repertoire passages. RESULTS: The 3 wind players (adventitious placebo controls) did not improve substantially. However, each pianist and guitarist showed marked and significant improvement in spontaneous repertoire performance without the splint. The first subject is now 25 months posttreatment. CONCLUSIONS: Results suggest that SMR is of value for the treatment of focal hand dystonia in pianists and guitarists.

Adult↗

PubMed2002

Longer versus shorter daily constraint-induced movement therapy of chronic hemiparesis: an exploratory study.

OBJECTIVE: To evaluate and compare the effects of 3-hour versus 6-hour daily training sessions in constraint-induced movement therapy (CIMT). DESIGN: Intervention study, 2-group randomized trial; baseline, pretreatment, and posttreatment measures; 1-month follow-up (weekly measures). SETTING: University department of psychology in Germany. PARTICIPANTS: A convenience sample of 15 adults with chronic hemiparesis (13 stroke, 2 traumatic brain injury). INTERVENTION: CIMT (14 consecutive days; constraint of unaffected hand for a target of 90% of waking hours) with either 6 hours (6h/d group, n=7) or 3 hours (3h/d group, n=8) of shaping training with the affected hand per day. MAIN OUTCOME MEASURES: The Motor Activity Log and Wolf Motor Function Test. RESULTS: Significant improvements in motor function in the laboratory and increased use of the affected hand in the real-world environment were found in both groups. The beneficial effects were significantly greater in the 6h/d group than in the 3h/d group. CONCLUSION: The 3-hour CIMT training schedule significantly improved motor function in chronic hemiparesis, but it was less effective than the 6-hour training schedule.

Adult↗

PubMed2002

Slow event-related brain activity of aphasic patients and controls in word comprehension and rhyming tasks.

Slow event-related potentials (ERP) were examined in healthy and aphasic subjects in two-stimulus designs comprising a word comprehension and a rhyming task. Aphasics, though selected to perform above chance level, made significantly more errors and responded more slowly than controls, although canonical correlations did not indicate a statistical relationship between performance measures and ERP amplitudes. A discriminant analysis of ERP amplitudes distinguished the groups for the slow wave (SW; 0.5-1.0 s post-S1 onset) in the word comprehension, for the SW and the initial contingent negative variation (iCNV; 1.0-2.0 s post-S1 onset) in the rhyming task. Similarly for both tasks, ERP topography showed left-anterior predominance of the negative SW and iCNV in controls, whereas participants with aphasia showed smaller anterior and larger left-posterior amplitudes. The centroparietal terminal CNV (tCNV; 1 s pre-S2) was smaller in participants with aphasia than in controls, but similar in topography. Results suggest left-anterior activation for those language processes that were presumably provoked in the present tasks, like lexical access, or phonological encoding. The pattern of participants with aphasia may indicate effects of language impairment and recovery, but also consequences of the brain damage.

Adult↗