Lrrk2 and Lewy body disease (original) (raw)
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Journal of Neuroscience, 2012
Following stroke, many patients suffer from chronic motor impairment and reduced somatosensation in the stroke-affected body parts. Recent experimental studies suggest that temporary functional deafferentation (TFD) of parts of the stroke-affected upper limb or of the less-affected contralateral limb might improve the sensorimotor capacity of the stroke-affected hand. The present study sought evidence of cortical reorganization and related sensory and motor improvements following pharmacologically induced TFD of the stroke-affected forearm.
Brain sensorimotor hand area functionality in acute stroke: insights from magnetoencephalography
NeuroImage, 2004
An understanding of the functional readjustments that the brain undergoes during the early days after a stroke would give us a major insight into how and how much neurons are capable to react to an insult. Thirty-two patients affected by an acute monohemispheric ischemic stroke were enrolled in the study. Magnetoencephalography was used to record the somatosensory-evoked fields (SEF) generated in response to median nerve stimulation. Latency, strength, and position of the related early cortical components (M20 and M30) were studied both separately within each hemisphere, and in terms of interhemispheric differences. Interhemispheric cross-correlations among SEF waveshapes in the two hemispheres were also investigated. Overall, except for some source displacement possibly induced by the perilesional edema, results did not demonstrate any unusual neural recruitment. The severity of the clinical picture was found related to the sources' strengths (both as absolute values and as interhemispheric differences), to excessive interhemispheric differences in SEF waveshapes and in the M30 latencies. Signs of an enhanced excitability were present in the affected hemisphere (AH) following a cortical lesion, usually in combination with preserved hand functionality. An enhanced excitability of the unaffected hemisphere (UH) was paired with larger lesions with cortical involvement; signs compatible with an abnormal transcallosal transmission and intracortical function of inhibitory GABAergic interneurons in the AH were found subtending UH enhancement. Spared responsiveness from Brodmann's area (BA) 2 and posterior parietal areas despite an altered response from BA 3b was found in six patients, combined to high hand functionality. Present results in acute phase increase the knowledge of the mechanisms governing brain adaptation/reaction capabilities, for future efforts to establish therapeutic and rehabilitative procedures. D
Sensory deficits in ipsilesional upper-extremity in chronic stroke patients
Arquivos de Neuro-Psiquiatria, 2015
Objective To investigate somatosensory deficits in the ipsilesional wrist and hand in chronic stroke patients and correlate these deficits with contralesional sensorimotor dysfunctions, functional testing, laterality and handedness.Methods Fifty subjects (twenty-two healthy volunteers and twenty-eight stroke patients) underwent evaluation with Semmes-Weinstein monofilaments, the sensory and motor Fugl-Meyer Assessment, the Nottingham Sensory Assessment in both wrists and hands and functional tests.Results Twenty-five patients had sensory changes in the wrist and hand contralateral to the stroke, and eighteen patients (64%) had sensory deficits in the ipsilesional wrist and hand. The most significant ipsilesional sensory loss was observed in the left-handed patients. We found that the patients with brain damage in the right hemisphere had better scores for ipsilesional tactile sensation.Conclusions A reduction in ipsilesional conscious proprioception, tactile or thermal sensation was...
Remodeling of somotasensory hand representations following cerebral lesions in humans
Neuroreport, 2002
There is evidence of reorganization of somatotopic maps following cortical lesions in mammals such as monkeys, raccoons and rats. However, there has been a striking lack of research on somatosensory plasticity following cerebral damage in adult humans. We describe two individuals with left hemisphere damage who misperceive the locations of tactile stimuli whose presence or absence they can readily detect.We find that the mislocalizations preserve the relative topography of pre-lesion experiences, resulting in shifted and compressed representations of the hand surfaces. These results not only provide evidence for systematic remodeling of somatotopic maps in humans, they also reveal that the systematic changes in cortical topography that have been documented using electrophysiological methods may give rise to similarly systematic changes in somatosensory perception itself. NeuroReport 13:207^211
Archives of Physical Medicine and Rehabilitation, 2003
Objective: To assess the effectiveness of a rehabilitative training program for deficits in somatic sensation and motor control of the hand in patients with pure sensory stroke. Design: Multiple baseline and before-after follow-up trial with behavioral analysis of single cases. Setting: Rehabilitation unit of a university hospital in Italy. Participants: Four patients were studied: 2 had a unilateral lesion confined to the parietal lobe (patients 1, 2), and 2 had a unilateral lesion of the thalamus (patients 3, 4) that also lapped the posterior limb of the internal capsule. All 4 patients had chronic deficits in somatic sensation and motor control of the contralesional hand. Intervention: Behavioral training consisting of exercises aimed at improving somatic sensation and motor control of the affected, contralesional hand. Thirty treatment sessions, each lasting 50 minutes, were performed. Main Outcome Measures: Somatic deficit was evaluated with 5 tests, and motor control deficit was assessed with 4 tests. One functional test estimated the influence of somatic deficit on daily activities. A visual analog scale (VAS) was also submitted to the patients' relatives to evaluate the amount of use of the affected arm in daily life activities. A baseline was obtained by recording each measure, except for the VAS, 4 times at the first evaluation session. Evaluation sessions were conducted before, after, and 6 months after the end of the experimental treatment. Results: All patients showed a stable baseline in at least 8 of the outcome measures. Patients 1 and 2 significantly improved in 9 and 7 outcome measures, respectively. Patients 3 and 4 improved in 4 and 7 outcome measures, respectively. With the exception of case 3, all patients considerably increased their use of the affected arm during daily life. The improvement was generally stable over a 6-month period, suggesting that the treatment had a long-term effect. Conclusions: Results suggest the possible effectiveness of our training program for treating somatic and motor control deficits of the hand in patients with cortical or subcortical pure sensory stroke.
Tactile direction discrimination in humans after stroke
Brain Communications, 2020
Sensing movements across the skin surface is a complex task for the tactile sensory system, relying on sophisticated cortical processing. Functional MRI has shown that judgements of the direction of tactile stimuli moving across the skin are processed in distributed cortical areas in healthy humans. To further study which brain areas are important for tactile direction discrimination, we performed a lesion study, examining a group of patients with first-time stroke. We measured tactile direction discrimination in 44 patients, bilaterally on the dorsum of the hands and feet, within 2 weeks (acute), and again in 28 patients 3 months after stroke. The 3-month follow-up also included a structural MRI scan for lesion delineation. Fifty-nine healthy participants were examined for normative direction discrimination values. We found abnormal tactile direction discrimination in 29/44 patients in the acute phase, and in 21/28 3 months after stroke. Lesions that included the opercular parietal...
Cortical Reorganization of Early Somatosensory Processing in Hemiparetic Stroke
The cortical motor system can be reorganized following a stroke, with an increasing recruitment of the contralesional hemisphere. However, it is unknown whether a similar hemispheric shift occurs in the somatosensory system to adapt to this motor change, and whether this is related to movement impairments. This proof-of-concept study assessed somatosensory evoked potentials (SEPs), P50 and N100, in hemiparetic stroke participants and age-matched controls using high-density electroencephalograph (EEG) recordings during tactile finger stimulation. The laterality index was calculated to determine hemispheric dominance of the SEP and re-confirmed with source localization. The study found that latencies of P50 and N100 were significantly delayed in stroke brains when stimulating the paretic hand. The amplitude of P50 was negatively correlated with Fügl-Meyer Upper Extremity Motor Score in stroke. Bilateral cortical responses were detected in stroke, while only contralateral cortical re...