***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: Abstract : Balanced transcallosal inhibition sustains symmetrical corticomotor excitability and assists the performance of bimanual voluntary movements . After stroke , transcallosal inhibition becomes asymmetric . This finding raised the notion that reducing poststroke asymmetry in transcallosal inhibition might prime the motor system before training and lead to improvements in walking recovery . In this study , we examined three neuromodulatory protocol s applied during walking to determine if they could increase ipsilesional and decrease contralesional motor excitability in patients with chronic stroke .  Inhibitory repetitive transcranial magnetic stimulation and inhibitory paired associative stimulation were applied to the contralesional motor system , and facilitatory anodal transcranial direct current stimulation was applied to the ipsilesional motor system . We tested the bilateral modulatory effects of each stimulation protocol on the tibialis anterior , medial gastrocnemius , medial hamstrings , and vastus lateralis of nine patients with chronic stroke . All stimulation protocol s increased paretic limb and decreased nonparetic limb motor excitability . There was no statistical difference in the extent of modulation between these stimulation protocol s. This result suggests these three protocol s are promising c and i date priming mechanisms for testing the hypothesis in a future study that reducing the poststroke asymmetry of between-hemisphere motor excitability will enhance the effect of gait therapy Glucose- and caffeine-containing energy drinks are said to influence the cognitive and cellular function within the brain . In this study , we have used the size of motor-evoked potentials ( MEPs ) produced in response to transcranial magnetic stimulation ( TMS ) of the motor cortex as an index of corticospinal excitability after ingestion of Lucozade and control drinks of glucose-containing or caffeine-containing carbonated water or carbonated water alone . With local ethical approval and informed consent , 10 healthy volunteers took part ; surface electromyographic ( EMG ) recordings were taken from the thenar muscles of the dominant h and . In each assessment , 15 TMS stimuli were delivered over the motor cortex at an intensity of 1.1 T. Six subjects ingested a 380-ml bottle of carbonated Lucozade drink containing 68 g of glucose and 46 mg caffeine . Four subjects took part in three control trials drinking : ( A ) carbonated water with caffeine , ( B ) carbonated water with glucose and ( C ) carbonated water alone . Assessment s were made before and at 30-min intervals after each drink . Mean fasting blood glucose concentrations and mean areas of MEPs rose after the Lucozade , remaining elevated for 90 min . Similar rises in MEP areas were seen in trials after drinking carbonated water with caffeine or with glucose , but not after drinking carbonated water alone . No change was seen in the M-wave evoked by electrical stimulation of the ulnar nerve . We conclude that Lucozade can affect the size of MEPs to activation of the motor cortex with fixed-intensity TMS . The underlying mechanism is likely to relate to the combined effects of caffeine and glucose on the brain Combined peripheral nerve and brain stimulation ( “ dual stimulation ” ) induces changes in the excitability of normal motor cortex . The authors sought to establish whether dual stimulation would also induce motor cortex plasticity and associated functional improvements in nine stroke patients with chronic stable hemiparesis . Following 4 weeks of daily dual stimulation , improvements were seen in some neurophysiological and functional measures . This technique may offer therapeutic opportunities in some stroke patients Paired associative stimulation ( PAS ) based on Hebb 's law of association can induce plastic changes in the intact human . The optimal interstimulus interval ( ISI ) between the peripheral nerve and transcranial magnetic stimulus is not known for muscles of the lower leg . The aims of this study were to investigate the effect of PAS for a variety of ISIs and to explore the efficacy of PAS when applied during dynamic activation of the target muscle . PAS was applied at 0.2 Hz for 30 min with the tibialis anterior ( TA ) at rest . The ISI was varied r and omly in seven sessions ( n = 5 ) . Subsequently , PAS was applied ( n = 14 , ISI = 55 ms ) with the TA relaxed or dorsi-flexing . Finally , an optimized ISI based on the subject somatosensory evoked potential ( SEP ) latency plus a central processing delay ( 6 ms ) was used ( n = 13 ) . Motor-evoked potentials ( MEPs ) were elicited in the TA before and after the intervention , and the size of the TA MEP was extracted . ISIs of 45 , 50 , and 55 ms increased and 40 ms decreased TA MEP significantly ( P = 0.01 ) . PAS during dorsi-flexion increased TA MEP size by 92 % ( P = 0.001 ) . PAS delivered at rest result ed in a nonsignificant increase ; however , when the ISI was optimized from SEP latency recordings , all subjects showed significant increases ( P = 0.002 ) . No changes in MEP size occurred in the antagonist . Results confirm that the excitability of the corticospinal projections to the TA but not the antagonist can be increased after PAS . This is strongly dependent on the individualized ISI and on the activation state of the muscle Magnetic stimulation of human primary motor cortex ( M1 ) paired with electrical stimulation of a peripheral motor nerve has been used to produce a lasting modulation of corticomotor ( CM ) excitability . This ' paired associative stimulation ' ( PAS ) protocol has been used to induce bidirectional changes in excitability in upper limb CM pathways . The present study tested the hypothesis that temporally dependent PAS applied to the common peroneal nerve during the swing phase of walking would induce bidirectional changes in CM excitability consistent with the Hebbian principle of activity-dependent plasticity . Fourteen subjects with no known neurological disorder participated in two data collection sessions each . PAS was delivered as a single block of 120 pairs of stimuli delivered in a 10 min period during treadmill walking at 4.0 km h(-1 ) . Changes in CM excitability were assessed by examining the size of motor potentials evoked by transcranial magnetic stimulation prior to and following PAS .  Tibialis anterior motor-evoked potentials amplitude increased to 121 % over baseline when the magnetic stimulus was delivered over M1 after the estimated arrival time of the afferent volley in sensorimotor cortex and decreased to 83 % of baseline when the magnetic stimulus was delivered prior to the estimated afferent volley arrival . This extent of modulation was undiminished following a further 10 min period of walking without stimulation . The temporal nature of the bidirectional effects following PAS , their rapid evolution and subsequent persistence supported the study 's hypothesis and were similar to the effects described by others in quiescent muscles of the upper limb To investigate how gait influences the perceived intensity of cutaneous input from the skin of the foot , the tibial or sural nerves were stimulated at the ankle  during walking or running on a treadmill .  As compared to st and ing , the detection threshold for these stimuli was raised by more than 30 % during the locomotion tasks . During walking , there was a phase-dependent modulation in perceived intensity of suprathreshold stimuli ( 1.5 , 2 , or 2.5 × PT ) . Stimuli given just prior to footfall were perceived as significantly above average ( Wilcoxon signed-rank test ) . In contrast there was a significant phasic decrease in sensitivity for shocks delivered immediately after ipsi- and contralateral footfall . The amplitude of somatosensory evoked potentials ( P50–N80 complex ) , simultaneously evoked from pulse trains to the sural nerve and recorded at scalp level , was , on average , 62 % of the level during st and ing . During gait , the amplitude of this complex was significantly smaller just after footfall than the amplitude during late swing ( MANOVA ) . It is suggested that the reduced sensation and the decreased evoked potentials after touchdown may be due to occlusion or masking by concomitant afferent input from the feet . On the other h and , the phasic increase in sensitivity at the end of swing is thought to result from a central ly generated facilitation of sensory transmission of signals in anticipation of foot-placing BACKGROUND Anodal transcranial direct current stimulation ( a-tDCS ) can facilitate primary motor cortex ( M1 ) , but the modulation of motor evoked potentials ( MEPs ) by a-tDCS varies between participants , and may depend on the balance between early versus late I-wave recruitment , as assessed by the difference in MEP latency between latero-medial and anterior-posterior cortical currents induced by transcranial magnetic stimulation ( TMS ) . OBJECTIVE To date , the dependence of tDCS after-effects on I-wave recruitment has only been investigated in intrinsic h and muscles . In order to better underst and the effects of tDCS across the upper limb , the present study examined I-wave recruitment and MEP modulation by a-tDCS or dual-hemisphere tDCS in muscles of the forearm ( Extensor Carpi Radialis ; ECR ) and proximal upper limb ( Biceps Brachii ; BB ) . METHODS We conducted a r and omized double-blind study with 18 healthy adults . Each received anodal , dual-hemisphere , or sham tDCS over M1 in separate sessions ( tDCS , 1 mA for 15 min ) . RESULTS Linear regression analyzes showed a-tDCS  modulated MEP size dependent on the latency difference in the ECR ( P = 0.01 ) but not BB ( P = 0.28 ) . Individuals with small MEP latency differences showed the expected facilitation of ECR MEPs after a-tDCS , whereas those with large MEP latency differences had suppressed ECR MEPs after a-tDCS . This relationship was not present after dual-hemisphere or sham tDCS in either muscle ( all P > 0.32 ) . CONCLUSIONS I-wave recruitment can predict the after-effects of a-tDCS in the distal but not proximal upper limb . These findings provide further insight into the variability of tDCS after-effects , and the relationship between I-wave recruitment and putative mechanisms of tDCS OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity 1 . Stimulation of the superficial peroneal or the sural nerve ( 3 shocks , 3 ms interval , 1 ms duration , 2.5 x perception threshold ) evoked a reflex activation of the tibialis anterior muscle at a latency of approximately 70 - 95 ms in all of nine healthy human subjects . Stimulation of the medial plantar nerve only rarely produced similar effects . The possibility that a transcortical pathway contributes to these late reflex responses was investigated by combining the cutaneous stimulations and a transcranial magnetic stimulation of the contralateral motor cortex . 2 . A significant facilitation of short-latency peaks in the post-stimulus time histogram of single tibialis anterior motor units evoked by the transcortical magnetic stimulation was observed in eight out of nine subjects following stimulation of the superficial peroneal or sural nerves at the latency of the long-latency reflex . In contrast such a facilitation was only rarely seen when the medial plantar nerve was stimulated . 3 . With the same timing for the stimuli , the superficial peroneal and sural nerve stimulations also produced a significant increase in the short-latency , presumed monosynaptic , facilitation of the tibialis anterior H reflex produced by the brain stimulation . 4 . Similar facilitatory effects of the cutaneous stimuli could not be demonstrated when the magnetic stimulation of the cortex was replaced with electrical stimulation , implying that cortical excitability is affected 
    Output:
    
Intervention stimulation parameters were highly variable across experiments , and whilst these appeared to influence efficacy , variations in the intervention and outcome assessment methods hindered the ability to draw conclusions about optimal parameters .