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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

P300 event-related potentials to counted (target) and uncounted (background) visual stimuli were recorded from subjects who had sustained either a right or a left middle cerebral artery cerebrovascular accident (CVA) and from appropriate normal control subjects. Subjects were asked to count target stimuli and to ignore non-target stimuli. Standard measurements of the amplitude and latency of P300 components as well as intercorrelations among P300 wave forms from 3 brain regions (Fz, Cz, Pz) were collected. Amplitudes of N1-P2 and N2-P3 components as well as overall amplitude of the ERP wave form were reliably reduced by a CVA, but component latencies were not significantly affected. The amplitude reduction associated with a CVA cannot be simply interpreted as evidence for reduced cognitive efficiency because overall amplitudes and intercorrelations between brain regions of CVA patients were reduced for both counted and uncounted stimuli. The intercorrelations between brain regions were particularly reduced if the CVA was localized in the right hemisphere. For CVA patients, reduced component amplitudes may reflect decreased cortical intercommunication associated with damage to subcortical brain structures.
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PMID:Cerebrovascular accident alters P300 event-related potential characteristics. 241 13

Electrical field distributions of event-related potentials (ERP's) were recorded during an auditory "oddball paradigm" and were analyzed in terms of time and space. Fourteen normal subjects and 14 chronic patients were cerebral thrombosis were studied. For the components N1 and P3 of the ERP's to target stimuli, reference-independent measures (latency, global field power, location of maximal or minimal potential, and location of centroids) were determined. Stroke patients displayed P3 abnormalities in latency, amplitude, and electrical field on the scalp. In addition, N1 electrical fields were also abnormal. These ERP abnormalities correlated significantly with the extent of mental function impairment in the stroke patients, and they improved after administration of a cerebral metabolic enhancer (Nefiracetam: DM-9384). The ERP's seemed to be sensitive in indicating the effects of the drug. These data suggest that time-course analysis of the spatial distribution of the ERP electrical field might be useful for evaluation of the extent of mental function impairment and the efficacy of drugs.
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PMID:Electric field distribution of event-related potentials in stroke patients. 872 19

The cardiovascular effects of the K-ATP channel blocker U-37883A and 5 related morpholinoguanidines were determined in 6 experimental preparations. In anesthetized dogs, U-37883A (0.5-8.0 mg/kg i.v.) increased mean arterial pressure (MAP; +18%) and left ventricular (LV) effective refractory period (ERP; +35%), and decreased LV contractility (-41%). Higher doses of U-37883A (16-32 mg/kg) fatally reduced MAP (-84%), heart rate (HR; -57%) and LV contractility (-72%). In anesthetized rats, U-37883A (1.0-50 mg/kg i.v.) also maximally reduced MAP, HR and LV contractility by 68, 77 and 48%, respectively. U-37883A and its analogs were diuretic in conscious rats (1.5-15 mg/kg i.v.) and blocked pinacidil in rabbit mesenteric artery (EC50 = 0.5-50 microM). In rabbit papillary muscle, 50 microM U-37883A significantly reduced force of contraction (-33%) and prolonged conduction time (+244%). Milder papillary effects were seen with the N'-OH analog U-45194A, which did not depress LV contractility in intact rats. In conscious dogs, oral U-45194A (50 mg/kg) was diuretic but reduced LV stroke volume and increased peripheral vascular resistance. These studies characterize U-37883A's systemic cardiovascular and direct myocardial effects, and identify U-45194A as a less cardiac depressant analog having U-37883A-like diuretic and functional K-ATP channel blocking activities.
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PMID:Cardiovascular effects of the K-ATP channel blocker U-37883A and structurally related morpholinoguanidines. 880 57

Cortical areas responsive to proprioceptive stimulation were assessed by ERP technique in normals and in selected patients with stroke and were compared to fMRI data. Repetitive extension of right and left forefinger elicited a P1/N1/P2 complex wave pattern. This pattern was absent in patient with complete sensory loss and present but spatially modified in patient with recovered sensory deficit. Source localization with a simple model showed three sources starting in the contralateral rolandic area (SI), then involving the inferior parietal lobe unilaterally and the supplementary motor area (10 to 134 ms). It was followed by a bilaterally distributed pattern of two sources located in the ipsilateral parietal region and in the contralateral insula. Right and left stimulation led to very symmetrical patterns. Comparison to fMRI obtained from passive extension of the wrist in normals showed very compatible data. We described in this paper, a sequential processing of proprioceptive inputs after passive movements involving primary and secondary sensory motor areas.
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PMID:Event-related potentials elicited by passive movements in humans: characterization, source analysis, and comparison to fMRI. 981 56

Assessment of intellectual functions is essential for rehabilitative interventions with traumatic brain injury and stroke patients. However, many of these patients are difficult or impossible to assess because of aphasia and physical disabilities that prevent their performance on traditionally administered tests of mental functioning. We present normative evidence obtained from healthy individuals for the efficacy of a new method of assessing such patients using standardized and validated tests formatted for computer presentation and using direct measures of brain activity (event-related brain potentials, ERP) as the measurable response instead of verbal or motor behavior.
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PMID:Performance on WISC-III and WAIS-R NI vocabulary subtests assessed with event-related brain potentials: an innovative method of assessment. 1055 Aug 5

There is a substantial body of basic research that has utilized ERPs to investigate the neurological basis of cognition. This research has, in turn, led to the development of practical applications of cognitive ERPs in patient populations. In particular, recent work has focused on the development of ERP-based assessment measures for the neuropsychological assessment of dyslexia and language impairments secondary to stroke. This review describes the innovative assessment methods program (IAMP), an initiative to utilize ERPs for a neuropsychological assessment of patients who cannot be evaluated by traditional methods. The success of this program has demonstrated that ERPs can be used to reliably evaluate an individual's reading and speech comprehension abilities, independent of behavioral and speech production impediments. In contrast to traditional neuropsychological assessment, these ERP methods can discern the cognitive strategies used by an individual to perform a task.
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PMID:The application of cognitive event-related brain potentials (ERPs) in language-impaired individuals: review and case studies. 1102 94

The brain processes of language recovery after stroke are poorly understood, partly because past research did not allow to differentiate the effects of spontaneous restitution processes from those of learning-related cortical reorganization. Here, we use a new approach offered by recently developed intense neuropsychological therapy methods, which allow for improving language functions within a short time period. Stroke patients with chronic aphasia received intense language therapy for 2 weeks and, over this period, improved their language performance as assessed using clinical tests. Neurophysiological activity elicited by words and pseudowords was measured before and after treatment. Over the therapy interval, early word evoked potentials (latency 250-300 ms) became significantly stronger whereas pseudoword responses did not change. Word-specific changes were documented by analyses of ERP amplitudes and root mean square values, which revealed interactions of the factors Assessment time (before vs. after therapy) and Wordness (word vs. pseudoword). Source localization using Minimum Norm Current Estimates showed that bilateral cortical sources activated by word stimuli contributed to the change, suggesting that neuronal networks distributed over both hemispheres are the substrate of cortical reorganization of language processing in intense aphasia therapy. Word-evoked differences in source strengths were significantly correlated with performance on a clinical language test, demonstrating a link between behavioral and neurophysiological changes. We suggest that the early word-evoked negativity might represent an index of reorganization of language after stroke and thus an aphasia recovery potential.
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PMID:Therapy-related reorganization of language in both hemispheres of patients with chronic aphasia. 1609 76

Motor task experiments play an essential role in exploring the brain mechanisms of movement control, and visual force-feedback is an important factor in these motor experiments. In this paper, the authors proposed a visual forcefeedback system suitable for neuroscience experiment. With this system, the force output produced by participants can be detected and recorded in real time, while force output was visually displayed as a feedback cue to the participants simultaneously. Furthermore, this force feedback system is MRI compatible, and can be used both in fMRI and ERP experiments. The proposed system has been applied in handgrip tasks and finger movement experiments, which were designed to explore the relationship between force output and brain activation mode in normal subject and stroke patient. The results demonstrated that various force levels were well detected and visual feedback signals enabled the accomplishment of experiments with both fixed and variable target force levels.
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PMID:An MRI compatible visual force-feedback system for the study of force control mechanics. 1728 Oct 27

Although the notion of the language specificity of neural correlates has been widely accepted in the past (e.g., lefthemispheric dominance including Broca's and Wernike's area, N400 ERP component of semantic processing, and the P600 ERP component of syntactic processing, etc.), recent studies have shown that music and language share some important neurological aspects in their processing, both involving bilateral hemispheric activities. In line with this are the frequent behavioral clinical observations that persons with aphasia show improved articulation and prosody of speech in musically assisted phrases. Connecting recent neurological findings with clinical observations would not only inform clinical practice but would enhance understanding of the neurological mechanisms involved in the processing of speech/language and music. This article presents a music therapy treatment protocol study of 7 nonfluent patients with aphasia. The data and findings are discussed with regard to some of the recent focuses and issues addressed in the experimental studies using cognitive-behavioral, electrophysiological, and brain-imaging techniques.
Top Stroke Rehabil
PMID:Protocol evaluation for effective music therapy for persons with nonfluent aphasia. 1915 63

Changes in brain activity characterizing impaired speech production after brain damage have usually been investigated by comparing aphasic speakers with healthy subjects because prestroke data are normally not available. However, when interpreting the results of studies of stroke patients versus healthy controls, there is an inherent difficulty in disentangling the contribution of neuropathology from other sources of between-subject variability. In the present work, we had an unusual opportunity to study an aphasic patient with severe anomia who had incidentally performed a picture naming task in an ERP study as a control subject one year before suffering a left hemisphere stroke. The fortuitous recording of this patient's brain activity before his stroke allows direct comparison of his pre- and poststroke brain activity in the same language production task. The subject did not differ from other healthy subjects before his stroke, but presented major electrophysiological differences after stroke, both in comparison to himself before stroke and to the control group. ERP changes consistently appeared after stroke in a specific time window starting about 250 msec after picture onset, characterized by a single divergent but stable topographic configuration of the scalp electric field associated with a cortical generator abnormally limited to left temporal posterior perilesional areas. The patient's pattern of anomia revealed a severe lexical-phonological impairment and his ERP responses diverged from those of healthy controls in the time window that has previously been associated with lexical-phonological processes during picture naming. Given that his prestroke ERPs were indistinguishable from those of healthy controls, it seems highly likely that the change in his poststroke ERPs is due to changes in language production processes as a consequence of stroke. The patient's neurolinguistic deficits, combined with the ERPs results, provide unique evidence for the role of left temporal cortex in lexical-phonological processing from about 250 to 450 msec during word production.
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PMID:ERP correlates of word production before and after stroke in an aphasic patient. 2004 96


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