human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective To describe the relationship between changes of cortico-spinal excitability and motor recovery of the affected h and after stroke . Methods Eighteen hemiparetic stroke patients with a severe-to-mild upper limb motor impairment were r and omized .  Cortico-spinal excitability measures ( resting motor thresholds and motor evoked potentials )  obtained from a distal ( abductor pollicis brevis ) and proximal ( biceps brachii ) upper limb muscle were assessed for both hemispheres . Motor function of the affected h and was tested by the Wolf Motor Function and Action Research Arm tests . The evaluations were performed at baseline and weekly over 7 weeks of in-patient neurological rehabilitation . Results Severe h and dysfunction was associated with a strong suppression of ipsilesional cortico-spinal excitability and a shift of excitability towards the contralesional hemisphere . Mild h and impairment was associated with a shift of cortico-spinal excitability towards the ipsilesional hemisphere . Favorable motor recovery correlated with an increase of ipsilesional cortico-spinal excitability OBJECTIVES The aim of this study is to describe the variability and other characteristics of the motor evoked potential ( MEP ) to transcranial magnetic stimulation ( TMS ) in a large data base . METHODS One hundred fifty one subjects , including 17 sib pairs , free of neurological or psychiatric disease and on no neuroactive medications were studied with uniform techniques . Nineteen were studied on 3 occasions . Measures included MEP threshold ( N=141 ) during rest and voluntary muscle activation and the response to paired TMS ( subthreshold conditioning stimulus ) at interstimulus intervals ( ISIs ) of 3 , 4 , 10 , and 15ms ( N=53 ) . RESULTS There was a large variability in all the measures . Approximately 40 - 50 % of this appeared to come from within-subjects variation or experimental error . The MEP threshold data were skewed downward , but normalized with log transformation . The paired-pulse ratios ( conditioned/unconditioned MEP ) were normally distributed except those from the 3ms ISI which had no lower tail and could not be normalized . There were subjects showing inhibition and others showing facilitation at all ISIs . There were no correlations in any of the data with age or sex , but MEP thresholds were highly correlated within sibs . CONCLUSIONS These data should be useful for planning , analyzing , and interpreting TMS studies in healthy and patient population OBJECTIVES The objective of this study was to assess the sensitivity of motor-evoked potentials ( MEPs ) elicited by transcranial magnetic stimulation ( TMS ) in demonstrating the possible sub clinical impairment of the corticospinal pathway after recovery , in patients with a clinical history of pure motor stroke ( PMS ) due to a single lacunar infa rct detectable by magnetic resonance imaging ( MRI ) . METHODS MEPs were recorded from the first dorsal interosseous muscle of 20 healthy subjects and 40 patients , 6 months or more after PMS onset . Patients were evaluated clinical ly by means of the NIH stroke scale , the Medical Research Council ( MRC ) scale and the Barthel Index . The patients with full h and strength recovery and the normal controls were also tested by means of the 9-hole peg test . RESULTS Motor threshold ( MT ) , MEP amplitude and central motor conduction time ( CMCT ) of the affected side were significantly different from those of the normal side and of the control subjects . MT , MEP amplitude and CMCT obtained after stimulation of the affected hemisphere were significantly correlated with the MRC scale values of the affected h and . Eighty-six percent of patients with persistent h and strength deficit showed MEP abnormalities . In 21 patients with complete clinical recovery , a significant increase in MT and decrease in MEP amplitude on the affected side were observed . CONCLUSIONS After PMS , neurophysiological changes may persist despite complete clinical recovery . TMS represents a sensitive tool that enables to demonstrate objective ly the clinical and sub clinical impairment of the corticospinal pathway Focal transcranial magnetic stimulation ( TCS ) was employed for the representation of the motor cortex in a population of 18 patients to investigate the functional properties of h and motor areas 2 - 4 months after a monohemispheric stroke . Eleven sites were stimulated to elicit motor evoked potentials ( MEPs ) in abductor digiti minimi muscle after TCS of affected ( AH ) and unaffected ( UH ) hemispheres ; recording sessions were performed at the beginning ( T1 ) and after 8 - 10 weeks ( T2 ) of neurorehabilitation . Barthel index and Canadian neurological scale scores were evaluated . A group of 20 healthy control subjects was enrolled . In stroke patients the AH was less excitable than normal , combined with a decrease in motor cortical output area ( P < 0.05 ) in T1 . In T2 , there was an enlargement of the h and motor area on the AH combined with an improvement of clinical scores ( P < 0.001 ) . In T1 and T2 , the amplitude of MEPs in the AH was reduced ( P < 0.001 ) with a prolongation of central conduction time ( P < 0.001 ) and with a tendency towards improvement in T2 ; the amplitude of contracted MEPs was larger than normal in the UH in T1 . Both in T1 and T2 , anomalous ' hot spot ' ( most excitable ) scalp sites , never seen in normals , were often encountered ( T2 > T1 ) on the AH and UH . Interhemispheric differences for topography and latency of MEPs were remarkably affected . Our data are consistent with a rearrangement of the brain motor cortical output between 2 and 4 months following stroke . The amelioration of the neurophysiological parameters was correlated with clinical improvement in disability and neurological scores . This study confirms the existence in adults of brain ' plasticity ' still operating between 2 and 4 months from an acute vascular monohemispheric insult Background and Purpose — The purpose of this research was to investigate the impact of lesion location on motor excitability and motor performance . Methods — We studied patients with pure motor strokes in 4 different brain areas : motor cortex lesions ( n=7 ) , striatocapsular lesions ( n=13 ) , lacunar lesions of the internal capsule ( n=13 ) , and paramedian pontine lesions ( n=10 ) . Motor performance tests included the 9-hole-peg test and grip strength recordings . Motor excitability was determined by transcranial magnetic stimulation .  Motor thresholds , stimulus-response curves , silent periods , motor cortical inhibition , and facilitation were investigated . Results — The 4 groups were clinical ly similar but showed major differences in motor excitability . Only motor cortex lesions had a loss of intracortical inhibition in the affected hemisphere . In the internal capsule lesion group and the pontine lesion group , stimulus-response curves were depressed on the affected side . All of the subcortical lesions showed a prolongation of the silent period in the paretic side . Motor thresholds were predominantly elevated in the lesioned hemisphere of patients with internal capsule or pontine lesions .  Motor performance was correlated with silent period duration in internal capsule lesions and with motor thresholds in internal capsule and pontine lesions . Conclusions — Motor cortex lesions exhibited deficient inhibitory properties . In contrast , subcortical lesions displayed an enhancement of inhibition . Internal capsule and pontine lesions affecting the corticospinal tract on different levels particularly impaired neuronal recruitment . Our results suggest that the lesion location determines a specific pattern of motor excitability changes Repetitive transcranial magnetic stimulation ( rTMS ) is a tool with antidepressant potential that uses a coil placed on the scalp to produce a powerful magnetic field that directly stimulates only the outermost cortex . MRI scans were obtained in 29 depressed adults involved in an rTMS antidepressant clinical treatment . These scans were analyzed to investigate the effect of distance from coil to cortex on clinical parameters . Longer motor cortex distance , but not prefrontal distance , strongly correlated with increased motor threshold ( P<0.01 ) . Clinical antidepressant response did not correlate with either distance . The rTMS antidepressant responders , however , were significantly younger ( t=-2.430 , P<0.05 ) , and there appears to be a maximum threshold of age and distance to prefrontal cortex for response OBJECTIVE Focal transcranial magnetic stimulation was used to test prospect ively corticospinal excitability changes and reorganization of first dorsal interosseous ( FDI ) motor cortical representation in 31 patients who experienced a first ischemic stroke in the middle cerebral artery territory . All had severe h and palsy at onset . METHODS Patients were assessed clinical ly with the Medical Research Council , Rankin , the National Institutes of Health stroke scales and Barthel Index at days 1 , 8 , 30 , 90 , 180 and 360 after stroke . The following parameters of FDI  motor evoked potential ( MEPS ) to focal transcranial magnetic stimulation were measured at the same delays : motor threshold , MEP amplitude , excitable cortical area , hot spot and center of gravity of FDI motor maps on affected and unaffected hemispheres . Correlations were sought between clinical and electrophysiological parameters . RESULTS In patients whose affected motor cortex remained excitable at day 1 , motor thresholds were not significantly different between sides and were similar to those of controls . Persistence of MEP on the affected side at day 1 was a strong predictor of good recovery . If present at day 1 , MEPs recorded in affected FDI were significantly smaller than of the opposite side or in normals and progressively recovered up to day 360 . In these patients , area of excitable cortex remained stable throughout the entire study . At day 1 , amplitudes of MEPs obtained in unaffected FDI were significantly larger than later . Between days 1 and 360 , we observed a significant displacement of center of gravity of motor maps towards more frontal regions on the affected side while no change was noted on the unaffected side . CONCLUSIONS Our data confirm the early prognosis value of transcranial magnetic stimulation in stroke . They indicate that the brain insult induces a transient hyperexcitability of the unaffected motor cortex . The evolution of FDI motor maps along the course of recovery mostly reflect corticospinal excitability changes but might also reveal some degree of brain plasticity . Most modifications observed occurred within 3 months of stroke onset The respective contributions of the stroke and undamaged hemispheres to motor recovery after stroke remains controversial . The aim of this article is to evaluate the relationship between location and size of cortical motor areas and outcome after stroke . Twelve controls and 12 stroke patients were studied . H and cortical motor output areas were determined using transcranial magnetic stimulation . Motor-evoked potentials were recorded simultaneously from both h and s. Functional motor abilities were evaluated using well-vali date d measures . Surface area , weighted surface area , and center of gravity of motor output areas were calculated . Different patterns of motor output areas to the paretic h and were observed ; there was no motor output from the stroke hemisphere in patients with poor outcome , contrasting to large motor output area in the stroke hemisphere in patients with good outcome , regardless of infa rct size or location . A significant correlation was found between measures of motor outcome in the stroke-affected upper extremity and both the surface area and weight of the central motor output area in the stroke hemisphere . No ipsilateral motor response was obtained after stimulation of either hemisphere . These data support an association between preservation of cortical motor output area to the paretic h and in the stroke hemisphere and good motor outcome Background . Evolution of changes in intracortical excitability following stroke , particularly in the contralesional hemisphere , is being increasingly recognized in relation to maximizing the potential for functional recovery . Objective . The present study utilized a prospect i ve longitudinal design over a 12-month period from stroke onset , to investigate the evolution of intracortical excitability involving both motor cortices and their relationship to recovery , and whether such changes were influenced by baseline stroke characteristics . Methods . Thirty-one patients with acute unilateral ischemic stroke were recruited from a tertiary hospital stroke unit . Comprehensive clinical assessment s and cortical excitability were undertaken at stroke onset using a novel threshold-tracking paired-pulse transcranial magnetic stimulation technique , and repeated at 3- , 6- , and 12-month follow-up in 17 patients who completed the longitudinal assessment . Results . Shortly following stroke , short-interval intracortical inhibition ( SICI ) was significantly reduced in both lesioned and contralesional hemispheres that correlated with degree of recovery over the subsequent 3 months . Over the follow-up period , ipsilesional SICI remained reduced in all patient groups , while SICI over the contralesional hemisphere remained reduced only in the groups with cortical stroke or more baseline functional impairment . Conclusions . The current study has demonstrated that evolution of intracortical excitability , particularly over the contralesional hemisphere , may vary between patients with differing baseline stroke and clinical characteristics , suggesting that ongoing contralesional network recruitment may be necessary for those patients who have significant disruptions to the integrity of ipsilesional motor pathways . Results from the present series have implication s for the development of neuromodulatory brain stimulation protocol s to harness and thereby facilitate stroke recovery 
    Output:
    
agent
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective To describe the relationship between changes of cortico-spinal excitability and motor recovery of the affected h and after stroke . Methods Eighteen hemiparetic stroke patients with a severe-to-mild upper limb motor impairment were r and omized .  Cortico-spinal excitability measures ( resting motor thresholds and motor evoked potentials )  obtained from a distal ( abductor pollicis brevis ) and proximal ( biceps brachii ) upper limb muscle were assessed for both hemispheres . Motor function of the affected h and was tested by the Wolf Motor Function and Action Research Arm tests . The evaluations were performed at baseline and weekly over 7 weeks of in-patient neurological rehabilitation . Results Severe h and dysfunction was associated with a strong suppression of ipsilesional cortico-spinal excitability and a shift of excitability towards the contralesional hemisphere . Mild h and impairment was associated with a shift of cortico-spinal excitability towards the ipsilesional hemisphere . Favorable motor recovery correlated with an increase of ipsilesional cortico-spinal excitability OBJECTIVES The aim of this study is to describe the variability and other characteristics of the motor evoked potential ( MEP ) to transcranial magnetic stimulation ( TMS ) in a large data base . METHODS One hundred fifty one subjects , including 17 sib pairs , free of neurological or psychiatric disease and on no neuroactive medications were studied with uniform techniques . Nineteen were studied on 3 occasions . Measures included MEP threshold ( N=141 ) during rest and voluntary muscle activation and the response to paired TMS ( subthreshold conditioning stimulus ) at interstimulus intervals ( ISIs ) of 3 , 4 , 10 , and 15ms ( N=53 ) . RESULTS There was a large variability in all the measures . Approximately 40 - 50 % of this appeared to come from within-subjects variation or experimental error . The MEP threshold data were skewed downward , but normalized with log transformation . The paired-pulse ratios ( conditioned/unconditioned MEP ) were normally distributed except those from the 3ms ISI which had no lower tail and could not be normalized . There were subjects showing inhibition and others showing facilitation at all ISIs . There were no correlations in any of the data with age or sex , but MEP thresholds were highly correlated within sibs . CONCLUSIONS These data should be useful for planning , analyzing , and interpreting TMS studies in healthy and patient population OBJECTIVES The objective of this study was to assess the sensitivity of motor-evoked potentials ( MEPs ) elicited by transcranial magnetic stimulation ( TMS ) in demonstrating the possible sub clinical impairment of the corticospinal pathway after recovery , in patients with a clinical history of pure motor stroke ( PMS ) due to a single lacunar infa rct detectable by magnetic resonance imaging ( MRI ) . METHODS MEPs were recorded from the first dorsal interosseous muscle of 20 healthy subjects and 40 patients , 6 months or more after PMS onset . Patients were evaluated clinical ly by means of the NIH stroke scale , the Medical Research Council ( MRC ) scale and the Barthel Index . The patients with full h and strength recovery and the normal controls were also tested by means of the 9-hole peg test . RESULTS Motor threshold ( MT ) , MEP amplitude and central motor conduction time ( CMCT ) of the affected side were significantly different from those of the normal side and of the control subjects . MT , MEP amplitude and CMCT obtained after stimulation of the affected hemisphere were significantly correlated with the MRC scale values of the affected h and . Eighty-six percent of patients with persistent h and strength deficit showed MEP abnormalities . In 21 patients with complete clinical recovery , a significant increase in MT and decrease in MEP amplitude on the affected side were observed . CONCLUSIONS After PMS , neurophysiological changes may persist despite complete clinical recovery . TMS represents a sensitive tool that enables to demonstrate objective ly the clinical and sub clinical impairment of the corticospinal pathway Focal transcranial magnetic stimulation ( TCS ) was employed for the representation of the motor cortex in a population of 18 patients to investigate the functional properties of h and motor areas 2 - 4 months after a monohemispheric stroke . Eleven sites were stimulated to elicit motor evoked potentials ( MEPs ) in abductor digiti minimi muscle after TCS of affected ( AH ) and unaffected ( UH ) hemispheres ; recording sessions were performed at the beginning ( T1 ) and after 8 - 10 weeks ( T2 ) of neurorehabilitation . Barthel index and Canadian neurological scale scores were evaluated . A group of 20 healthy control subjects was enrolled . In stroke patients the AH was less excitable than normal , combined with a decrease in motor cortical output area ( P < 0.05 ) in T1 . In T2 , there was an enlargement of the h and motor area on the AH combined with an improvement of clinical scores ( P < 0.001 ) . In T1 and T2 , the amplitude of MEPs in the AH was reduced ( P < 0.001 ) with a prolongation of central conduction time ( P < 0.001 ) and with a tendency towards improvement in T2 ; the amplitude of contracted MEPs was larger than normal in the UH in T1 . Both in T1 and T2 , anomalous ' hot spot ' ( most excitable ) scalp sites , never seen in normals , were often encountered ( T2 > T1 ) on the AH and UH . Interhemispheric differences for topography and latency of MEPs were remarkably affected . Our data are consistent with a rearrangement of the brain motor cortical output between 2 and 4 months following stroke . The amelioration of the neurophysiological parameters was correlated with clinical improvement in disability and neurological scores . This study confirms the existence in adults of brain ' plasticity ' still operating between 2 and 4 months from an acute vascular monohemispheric insult Background and Purpose — The purpose of this research was to investigate the impact of lesion location on motor excitability and motor performance . Methods — We studied patients with pure motor strokes in 4 different brain areas : motor cortex lesions ( n=7 ) , striatocapsular lesions ( n=13 ) , lacunar lesions of the internal capsule ( n=13 ) , and paramedian pontine lesions ( n=10 ) . Motor performance tests included the 9-hole-peg test and grip strength recordings . Motor excitability was determined by transcranial magnetic stimulation .  Motor thresholds , stimulus-response curves , silent periods , motor cortical inhibition , and facilitation were investigated . Results — The 4 groups were clinical ly similar but showed major differences in motor excitability . Only motor cortex lesions had a loss of intracortical inhibition in the affected hemisphere . In the internal capsule lesion group and the pontine lesion group , stimulus-response curves were depressed on the affected side . All of the subcortical lesions showed a prolongation of the silent period in the paretic side . Motor thresholds were predominantly elevated in the lesioned hemisphere of patients with internal capsule or pontine lesions .  Motor performance was correlated with silent period duration in internal capsule lesions and with motor thresholds in internal capsule and pontine lesions . Conclusions — Motor cortex lesions exhibited deficient inhibitory properties . In contrast , subcortical lesions displayed an enhancement of inhibition . Internal capsule and pontine lesions affecting the corticospinal tract on different levels particularly impaired neuronal recruitment . Our results suggest that the lesion location determines a specific pattern of motor excitability changes Repetitive transcranial magnetic stimulation ( rTMS ) is a tool with antidepressant potential that uses a coil placed on the scalp to produce a powerful magnetic field that directly stimulates only the outermost cortex . MRI scans were obtained in 29 depressed adults involved in an rTMS antidepressant clinical treatment . These scans were analyzed to investigate the effect of distance from coil to cortex on clinical parameters . Longer motor cortex distance , but not prefrontal distance , strongly correlated with increased motor threshold ( P<0.01 ) . Clinical antidepressant response did not correlate with either distance . The rTMS antidepressant responders , however , were significantly younger ( t=-2.430 , P<0.05 ) , and there appears to be a maximum threshold of age and distance to prefrontal cortex for response OBJECTIVE Focal transcranial magnetic stimulation was used to test prospect ively corticospinal excitability changes and reorganization of first dorsal interosseous ( FDI ) motor cortical representation in 31 patients who experienced a first ischemic stroke in the middle cerebral artery territory . All had severe h and palsy at onset . METHODS Patients were assessed clinical ly with the Medical Research Council , Rankin , the National Institutes of Health stroke scales and Barthel Index at days 1 , 8 , 30 , 90 , 180 and 360 after stroke . The following parameters of FDI  motor evoked potential ( MEPS ) to focal transcranial magnetic stimulation were measured at the same delays : motor threshold , MEP amplitude , excitable cortical area , hot spot and center of gravity of FDI motor maps on affected and unaffected hemispheres . Correlations were sought between clinical and electrophysiological parameters . RESULTS In patients whose affected motor cortex remained excitable at day 1 , motor thresholds were not significantly different between sides and were similar to those of controls . Persistence of MEP on the affected side at day 1 was a strong predictor of good recovery . If present at day 1 , MEPs recorded in affected FDI were significantly smaller than of the opposite side or in normals and progressively recovered up to day 360 . In these patients , area of excitable cortex remained stable throughout the entire study . At day 1 , amplitudes of MEPs obtained in unaffected FDI were significantly larger than later . Between days 1 and 360 , we observed a significant displacement of center of gravity of motor maps towards more frontal regions on the affected side while no change was noted on the unaffected side . CONCLUSIONS Our data confirm the early prognosis value of transcranial magnetic stimulation in stroke . They indicate that the brain insult induces a transient hyperexcitability of the unaffected motor cortex . The evolution of FDI motor maps along the course of recovery mostly reflect corticospinal excitability changes but might also reveal some degree of brain plasticity . Most modifications observed occurred within 3 months of stroke onset The respective contributions of the stroke and undamaged hemispheres to motor recovery after stroke remains controversial . The aim of this article is to evaluate the relationship between location and size of cortical motor areas and outcome after stroke . Twelve controls and 12 stroke patients were studied . H and cortical motor output areas were determined using transcranial magnetic stimulation . Motor-evoked potentials were recorded simultaneously from both h and s. Functional motor abilities were evaluated using well-vali date d measures . Surface area , weighted surface area , and center of gravity of motor output areas were calculated . Different patterns of motor output areas to the paretic h and were observed ; there was no motor output from the stroke hemisphere in patients with poor outcome , contrasting to large motor output area in the stroke hemisphere in patients with good outcome , regardless of infa rct size or location . A significant correlation was found between measures of motor outcome in the stroke-affected upper extremity and both the surface area and weight of the central motor output area in the stroke hemisphere . No ipsilateral motor response was obtained after stimulation of either hemisphere . These data support an association between preservation of cortical motor output area to the paretic h and in the stroke hemisphere and good motor outcome Background . Evolution of changes in intracortical excitability following stroke , particularly in the contralesional hemisphere , is being increasingly recognized in relation to maximizing the potential for functional recovery . Objective . The present study utilized a prospect i ve longitudinal design over a 12-month period from stroke onset , to investigate the evolution of intracortical excitability involving both motor cortices and their relationship to recovery , and whether such changes were influenced by baseline stroke characteristics . Methods . Thirty-one patients with acute unilateral ischemic stroke were recruited from a tertiary hospital stroke unit . Comprehensive clinical assessment s and cortical excitability were undertaken at stroke onset using a novel threshold-tracking paired-pulse transcranial magnetic stimulation technique , and repeated at 3- , 6- , and 12-month follow-up in 17 patients who completed the longitudinal assessment . Results . Shortly following stroke , short-interval intracortical inhibition ( SICI ) was significantly reduced in both lesioned and contralesional hemispheres that correlated with degree of recovery over the subsequent 3 months . Over the follow-up period , ipsilesional SICI remained reduced in all patient groups , while SICI over the contralesional hemisphere remained reduced only in the groups with cortical stroke or more baseline functional impairment . Conclusions . The current study has demonstrated that evolution of intracortical excitability , particularly over the contralesional hemisphere , may vary between patients with differing baseline stroke and clinical characteristics , suggesting that ongoing contralesional network recruitment may be necessary for those patients who have significant disruptions to the integrity of ipsilesional motor pathways . Results from the present series have implication s for the development of neuromodulatory brain stimulation protocol s to harness and thereby facilitate stroke recovery 
    Output:
    