the dominant hand is defined as the hand that is usually used in performing activities of 
 daily living ( adl ) . the development of the motor function of the cerebral cortex is 
 asymmetrical to the dominant hand1 . based 
 on such asymmetrical development of the cerebral cortex , when the left hand is performing a 
 task , the cerebral cortex motor area of the right cerebral hemisphere activates . however , a 
 more interesting fact is that when the right hand is used functionally , the nerve cells of 
 the entire cerebral cortex motor area of the right and left cerebral hemispheres 
 activate2 . this finding supports the 
 evidence of lateralization of the cerebral hemisphere and implies that the left cerebral 
 hemisphere acts the role of the dominant cerebral hemisphere when performing adl2 , 3 . thus , the left hemisphere , which is the dominant cerebral hemisphere due to the 
 lateralization of the cerebral hemisphere , is more closely related with motor planning in 
 adl performance , and the same relationships were shown after cerebral hemisphere injury due 
 to stroke3 , 4 . characteristically , the patient with stroke - damaged dominant left 
 cerebral hemisphere reports a time delay on the exercise performance of both right and left 
 hands , whereas the patient with damaged right cerebral hemisphere reports a mild motor 
 function disorder confined to the left hand3 . this means that , consequently , after stroke onset , the patient with 
 hemiplegic dominant hand ( right ) experiences more difficulty in performing adl5 . however , regarding upper extremity 
 rehabilitation , there is no study that differentiated the motor function recovery of the 
 upper extremity of patients who are affected in the dominant cerebral hemisphere ( with the 
 hemiplegic right hand ) or in the non - dominant cerebral hemisphere ( with the hemiplegic left 
 hand ) . a specific rehabilitation approach based on laterality through classification of 
 cerebral damage on the right or left side thus , the purpose of this study is to determine 
 whether two - handed task training is effective in the motor learning of the injured cerebral 
 cortex activation and upper extremity function recovery after stroke . one patient was affected on the 
 dominant side of the body and the other patient was affected on the non - dominant side of the 
 body . patients with diagnosed stroke ( hemorrhagic / infarction ) > 6 months , with no 
 cognitive impairment ( mini mental state examination , mmse - k 24 ) , with > 58 points on the 
 fugl - meyer motor assessment of upper extremities6 were included in the study . the exclusion criteria of this study 
 were severely impaired internal carotid artery , intracranial metallic implant , and/or 
 seizure . this study 
 followed the ethical principles of the declaration of helsinki , and all patients gave 
 written informed consent before participating in this study . a magpro r30 transcranial 
 magnetic stimulation ( tms ) equipment ( medtronic , skovlunde , denmark ) was used to measure the 
 changes in excitability of the corticospinal tract . to determine the exact location of the 
 motor cortex area of the first dorsal interosseous ( fdi ) , we used a single stimulus , moving 
 the location on the head of subject using a coil stimulator . in the fdi electrograph , the 
 point where the biggest motor evoked potential ( mep ) appeared was considered as the motor 
 cortex area . the resting motor threshold was defined as the least stimulus strength from 
 which > 50 v was recorded at least more than 5 out of 10 stimuli ; the amplitude and 
 latency values of the mep that was stimulated by 120% were measured 15 times and 
 averaged7 . in addition , the manual 
 function test was used to determine the overall function of the upper extremity8 . the two subjects were trained twice a week , 
 for 6 weeks ( total , 12 times ) . after the training ended , the two subjects underwent upper 
 extremity function reassessment ; each subject was reassessed once and analyzed 12 times in 
 total for possession examinations 2 weeks later and 3 months later . every subject chose the 
 functional task training that uses a two - handed task often in everyday life as the 
 therapeutic intervention of upper extremity rehabilitation . the two - handed tasks training 
 program included the following exercises : ( 1 ) washing of hands : hand washing using real soap 
 in a basin in the treatment room , with the therapist offering a bit of support as needed ; 
 ( 2 ) putting on clothes : putting on the top half of a patient gown after getting undressed , 
 with the therapist offering a bit of support as needed ; ( 3 ) scissoring : using a certain size 
 of scissors , the patient cuts a thick sheet of a4-size paper , with the therapist offering a 
 bit of support as needed ; ( 4 ) opening a bottle cap : this involves opening a soda bottle cap 
 using a bottle opener , with the therapist offering a bit of support as needed ; ( 5 ) muscular 
 strength training : training both hands using two jamar hand dynamometer , with 
 the therapist offering a bit of support as needed . each task was performed for 6 minutes , 
 and all tasks were accomplished in 30 minutes ; the order of tasks was random . a graph was 
 used to analyze the effect of the two - handed task with or without a dominant hand deficit on 
 cerebral cortex activation and upper extremity function recovery . the mep amplitude in subject 1 ( with the hemiplegic dominant hand [ right ] ) increased from 
 0.13  mv in the pre - training period to 0.27  mv after 12 sets of training , to 0.25  mv after 2 
 weeks , and to 0.24  mv after 3 months ( table 
 1table 1.changes in the motor - evoked potential amplitude ( mv ) of subjects 1 and 2baseinterventionretention1234567891011subject 1 ( dominant)0.130.120.130.120.160.190.180.220.270.250.24subject 2 ( non - dominant)0.360.350.360.430.460.460.450.470.460.440.42 ) . the latency period decreased from 24.23  ms in the pre - training period to 
 23.03  ms after a total of 12 sets of training , to 23.5  ms after 2 weeks , and to 23.72  ms 
 after 3 months ( table 2table 2.changes in the motor - evoked potential latency ( msec ) of subjects 1 and 2baseinterventionretention1234567891011subject 1 ( dominant)24.224.324.223.5923.47723.4923.2423.3223.0323.523.72subject 2 ( non - dominant)2524.9724.8325.0124.5724.6124.6824.4924.4424.3524.6 ) . the average of the mep amplitude in subject 2 ( with the hemiplegic 
 non - dominant hand [ left ] ) increased from 0.36  mv in the pre - training period to 0.46  mv after 
 12 sets of training , to 0.44  mv after 2 weeks , and to 0.42  mv after 3 months ( table 1 ) . the latency period decreased from 24.93  ms 
 in the pre - training period to 24.44  ms after a total of 12 sets of training , to 24.35  ms at 
 the possession examination after 2 weeks , and to 24.6  ms at the possession examination after 
 3 months ( table 2 ) . mft was used to assess both 
 subjects 1 and 2 at base terms , i.e. , the terms of arbitration and possession examination of 
 training of both hands . the average mft of subject 1 increased from 19.3 to 21 points and 
 was maintained at 21 points at the possession examination conducted after 2 weeks and 3 
 months ( table 3table 3.changes in the manual function test ( mft ) score of subjects 1 and 2baseinterventionretention1234567891011subject 1 ( dominant)1919201919212121212121subject 2 ( non - dominant)2525252526262626262626 ) . the average mft of subject 2 increased from 25 to 26 points after the 
 training ended and was maintained at 26 points at the possession examination conducted after 
 2 weeks and 3 months ( table 3 ) . this study was conducted to investigate , in the context of two - handed task training , how 
 therapeutic intervention in patients with hemiplegic dominant hand ( right ) and hemiplegic 
 non - dominant hand ( left ) affects both sides of cerebral cortex activation and the variation 
 of learning and upper extremity motor function recovery , since most tasks in daily life 
 require the use of both hands . according to a previous study using tms , representation can 
 be effected on the primary motor area ( m1 ) of the cerebral cortex , and the mep values 
 obtained through tms can confirm the changes in relevant areas more accurately and 
 effectively9 . characteristically , some 
 features such as the hemiplegic side showing higher stimulus threshold , lower mep values , 
 and delayed mep latency period , compared with the non - hemiplegic side , were observed9,10,11 . this study repeatedly measured the 
 variables expressed in the m1 area of the cerebral cortex to determine the average meps and 
 delayed latency time of the affected side using tms to check for upper extremity motor 
 function learning in stroke patients . the increased average meps of the cerebral cortex and 
 the reduction in delayed latency time in both subjects 1 and 2 were confirmed through the 
 comparison of values before and after training . these results provide support for research 
 that intensive and repetitive upper extremity functional training can improve brain 
 plasticity of cerebral cortex brain regions in stroke patients11 . furthermore , this study ascertained that intensive and 
 repetitive upper extremity function training with and without the use of the hemiplegic 
 dominant hand shows a difference in cerebral cortex activation . in contrast , when the task 
 training involved both hands , no difference in cerebral cortex activation takes place . in 
 this study , comparison of the two subjects before and after training confirmed the increase 
 in average meps and the decrease in delayed latency time in the patient with hemiplegic 
 dominant hand . this suggest that the same task training using both hands may result in a 
 difference in the restoration of upper extremity function depending on the use of the 
 hemiplegic dominant hand in stroke patients . this study also shows an increased activity in 
 the left cerebral cortex ( dominant hand ) rather than the right cerebral cortex ( non - dominant 
 hand ) in the task training of both hands in functional adl , which can lead to better motor 
 recovery in patients with right hemiplegia ( dominant hand ) . the results show the possible 
 function of the corpus callosum , which connects the m1 or supplementary motor area with the 
 interhemispheric area , in increasing the activity of the damaged cerebral hemisphere when 
 task training with both hands12 . in 
 addition , this study has determined that the activation of the left cerebral cortex 
 ( dominant hand ) was further increased by task training using both hands . the frequency of 
 using the right hand at a given time is much higher than that of the left hand , even if the 
 task was performed with both hands , because the right hand plays a role in mobility , whereas 
 the left is for stability . these have the same context as the report that showed that the 
 activation of the cerebral cortex on functional magnetic resonance imaging increases with 
 increasing rate of movement12 , 13 . although this study showed a change in trend while the 
 two subjects ( one dominant hand [ right ] and one non - dominant hand [ left ] ) were performing , 
 hemisphere dominance was difficult to generalize statistically because of the small number 
 of subjects . this study on two - handed task performance was conducted with adl in mind , not 
 only stereotyped paradigm inducing bilateral symmetrical movements , and identified changes 
 in cerebral cortex activation and upper extremity functional recovery in stroke patients 
 according to dominant hand . in the future , a specific upper extremity rehabilitation 
 approach is necessary , one that recognizes movement difference between the dominant and 
 non - dominant hands by considering the different movement dominance of the right and left 
 hemispheres .
[ purpose ] the purpose of this study was to determine whether two - handed task training is 
 effective on motor learning of injured cerebral cortex activation and upper extremity 
 function recovery after stroke . 
 [ subjects and methods ] two hemiplegic subjects 
 participated in this study : one patient was affected on the dominant side of the body and 
 the other was affected on the non - dominant side of the body , and both scored in the range 
 of 5866 in the fugl - meyer assessment . 
 the excitability of the corticospinal tract and 
 manual function test were examined . 
 [ results ] the excitability of the corticospinal tract 
 and the manual function test showed significant differences in the activation of both 
 sides of the cerebral cortex and in the variation in learning effect of upper extremity 
 motor function recovery in patients with hemiplegic non - dominant hand ( left ) . 
 [ conclusion ] 
 the results suggested that two - handed task training had a different influence on dominant 
 hand ( right ) and non - dominant hand ( left ) motor recovery .