Study On Chinese Writing Related Cortical Areas Mapped By Navigated Transcranial Magnetic Stimulation

Objective: To identify Chinese character writing related cortex(WRC)is important for removing lesions around this region.This is the first study to investigate cortical mapping associated with Chinese character writing using navigated magnetic stimulation(nTMS).The relationship between Chinese Writing and hand motor cortical areas or motor speech center is also aimed to explore.Methods:(1)Ten native Chinese-speaking,right handed volunteers participated in the study with a mean age of 25.5 years.None of the subjects had a learning disability or a history of neurological disorders.Written informed consent was provided by all subjects before participation.The study was approved by the Ethics Committee of Tianjin Medical University General Hospital.Picture naming task was performed during nTMS mapping.(2)The high-resolution T1 MRI series described above was uploaded to TMS neuronavigation software(Brain Sight2.0,Rogue Research Inc.,Montreal,QC)for 3-dimensional brain surface model reconstruction.The right-hand motor representations were mapped while motor-evoked potentials(MEPs)were produced under nTMS stimulation.(3)10 subjects completed the picture naming task through the E-prime software.r The wrong type and error sites of subjects was recorded,and the location of the motor speech center was described.(4)The Chinese writing related areas were mapped when corresponding cortices was stimulated.These cortices caused impairment of Chinese character writing at meanwhile without electromyography(EMG)from abductor pollicis brevis(APB),abductor digiti minimi(ADM)and first dorsal interosseous(FDI).EMG data from APB,ADM and FDI as well as coordinates of positive stimulus were recorded.The extent and area of writing related cortex was calculated.(5)The writing-related functional area,Broca' area and the hand motor area were calculated in the preset matrix.The distance was calculated between the closest functional points of each functional area,and the distance as well as the relationship between each functional area was analyzed on the basis of area comparison and distance calculation.Result: The cortical areas related to Chinese character writing were mapped successfully in all subjects by nTMS,primarily centered in left posterior middle frontal gyrus(p MFG)(86%,55/64).The mean WRC area(161.03±62.58mm2)was significantly smaller than the mean HMC area(589.50±227.34mm2)(p<0.001).The WRC and HMC were not conjoined or overlapped in the dominant hemisphere.The distance between them was 12.58±2.71 mm.The mean Broca area was 7.98±3.32 mm,The results vary widely in the brain table position and most of the distance is less than 10 mm.Conclusion: nTMS can provide reliable assistance in WRC mapping areas.The WRC is relatively fixed and centralized in p MFG,not continuous to the HMC.Thus,noninvasive nTMS mapping could be used to study the cortical and subcortical connectivity of complex cognitive functions such as language,writing and memory,combined with functional magnetic resonance imaging(f MRI),electroencephalograph(EEG)and direct electrical stimulation(DES),and provides reliable evidence for operative strategies and postoperative neuroplasticity in neurosurgical settings.