1.Milner B, Squire LR, Kandel ER. Cognitive neuroscience and the study of memory. Neuron 1998;20:445-468.2.Baddeley A. Working memory. Science 1992;255:556-559.3.Constantinidis C, Procyk E. The primate working memory networks. Cogn Affect Behav Neurosci 2004;4:444-465.4.Gazzaley A, Rissman J, Desposito M. Functional connectivity during working memory maintenance. Cogn Affect Behav Neurosci 2004;4:580-599.5.Smith EE, Jonides J. Storage and executive processes in the frontal lobes. Science 1999;283:1657-1661.6.Barker AT, Jalinous R, Freeston IL. Non-invasive magnetic stimulation of human motor cortex. Lancet 1985;1:1106-1107.7.Bourland JD, Mouchawar GA, Nyenhuis JA, Geddes LA, Foster KS, Jones JT, et al. Transchest magnetic (eddy-current) stimulation of the dog heart. Med Biol Eng Comput 1990;28:196-198.8.George MS, Nahas Z, Kozel FA, Li X, Denslow S, Yamanaka K, et al. Mechanisms and state of the art of transcranial magnetic stimulation. J Ect 2002;18:170-181.9.George MS, Nahas Z, Kozol FA, Li X, Yamanaka K, Mishory A, et al. Mechanisms and the current state of transcranial magnetic stimulation. CNS Spectr 2003;8:496-514.10.Pascual-Leone A, Torres F. Plasticity of the sensorimotor cortex representation of the reading finger in Braille readers. Brain 1993;116 ( Pt 1):39-52.11.Cohrs S, Tergau F, Riech S, Kastner S, Paulus W, Ziemann U, et al. High-frequency repetitive transcranial magnetic stimulation delays rapid eye movement sleep. Neuroreport 1998;9:3439-3443.12.Martin JL, Barbanoj MJ, Perez V, Sacristan M. Transcranial magnetic stimulation for the treatment of obsessive-compulsive disorder. Cochrane Database Syst Rev 2003:CD003387.13.McNamara B, Ray JL, Arthurs OJ, Boniface S. Transcranial magnetic stimulation for depression and other psychiatric disorders. Psychol Med 2001;31:1141-1146.14.Pascual-Leone A, Rubio B, Pallardo F, Catala MD. Rapid-rate transcranial magnetic stimulation of left dorsolateral prefrontal cortex in drug-resistant depression. Lancet 1996;348:233-237.15.Forrester LW, Hanley DF, Macko RF. Effects of treadmill exercise on transcranial magnetic stimulation-induced excitability to quadriceps after stroke. Arch Phys Med Rehabil 2006;87:229-234.16.Heide G, Witte OW, Ziemann U. Physiology of modulation of motor cortex excitability by low-frequency suprathreshold repetitive transcranial magnetic stimulation. Exp Brain Res 2006;171:26-34.17.Pascual-Leone A, Tormos JM, Keenan J, Tarazona F, Canete C, Catala MD. Study and modulation of human cortical excitability with transcranial magnetic stimulation. J Clin Neurophysiol 1998;15:333-343.18.Rizzo V, Siebner HR, Modugno N, Pesenti A, Munchau A, Gerschlager W, et al. Shaping the excitability of human motor cortex with premotor rTMS. J Physiol 2004;554:483-495.19.Pascual-Leone A, Hallett M. Induction of errors in a delayed response task by repetitive transcranial magnetic stimulation of the dorsolateral prefrontal cortex. Neuroreport 1994;5:2517-2520.20.Grafman J, Wassermann E. Transcranial magnetic stimulation can measure and modulate learning and memory. Neuropsychologia 1999;37:159-167.21.Mottaghy FM, Doring T, Muller-Gartner HW, Topper R, Krause BJ. Bilateral parieto-frontal network for verbal working memory: an interference approach using repetitive transcranial magnetic stimulation (rTMS). Eur J Neurosci 2002;16:1627-1632.22.Rektorova I, Megova S, Bares M, Rektor I. Cognitive functioning after repetitive transcranial magnetic stimulation in patients with cerebrovascular disease without dementia: a pilot study of seven patients. J Neurol Sci 2005;229-230:157-161.23.Kim YH, Park JW, Ko MH, Jang SH, Lee PK. Facilitative effect of high frequency subthreshold repetitive transcranial magnetic stimulation on complex sequential motor learning in humans. Neurosci Lett 2004;367:181-185.24.Kim YH, You SH, Ko MH, Park JW, Lee KH, Jang SH, et al. Repetitive transcranial magnetic stimulation-induced corticomotor excitability and associated motor skill acquisition in chronic stroke. Stroke 2006;37:1471-1476.25.Nitsche MA, Paulus W. Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation. J Physiol 2000;527 Pt 3:633-639.26.Antal A, Nitsche MA, Paulus W. External modulation of visual perception in humans. Neuroreport 2001;12:3553-3555.27.Marshall L, Molle M, Hallschmid M, Born J. Transcranial direct current stimulation during sleep improves declarative memory. J Neurosci 2004;24:9985-9992.28.Marshall L, Molle M, Siebner HR, Born J. Bifrontal transcranial direct current stimulation slows reaction time in a working memory task. BMC Neurosci 2005;6:23.29.Boggio PS, Ferrucci R, Rigonatti SP, Covre P, Nitsche M, Pascual-Leone A, et al. Effects of transcranial direct current stimulation on working memory in patients with Parkinson's disease. J Neurol Sci 2006;249:31-38.30.Fregni F, Boggio PS, Nitsche M, Bermpohl F, Antal A, Feredoes E, et al. Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory. Exp Brain Res 2005;166:23-30.31.Wassermann EM, Grafman J. Recharging cognition with DC brain polarization. Trends Cogn Sci 2005;9:503-505.32.Mull BR, Seyal M. Transcranial magnetic stimulation of left prefrontal cortex impairs working memory. Clin Neurophysiol 2001;112:1672-1675.33.Mottaghy FM, Krause BJ, Kemna LJ, Topper R, Tellmann L, Beu M, et al. Modulation of the neuronal circuitry subserving working memory in healthy human subjects by repetitive transcranial magnetic stimulation. Neurosci Lett 2000;280:167-170.34.Rami L, Gironell A, Kulisevsky J, Garcia-Sanchez C, Berthier M, Estevez-Gonzalez A. Effects of repetitive transcranial magnetic stimulation on memory subtypes: a controlled study. Neuropsychologia 2003;41:1877-1883.35.Jahanshahi M, Profice P, Brown RG, Ridding MC, Dirnberger G, Rothwell JC. The effects of transcranial magnetic stimulation over the dorsolateral prefrontal cortex on suppression of habitual counting during random number generation. Brain 1998;121 (Pt 8):1533-1544.36.Pascual-Leone A, Walsh V, Rothwell J. Transcranial magnetic stimulation in cognitive neuroscience--virtual lesion, chronometry, and functional connectivity. Curr Opin Neurobiol 2000;10:232-237.37.Boroojerdi B, Phipps M, Kopylev L, Wharton CM, Cohen LG, Grafman J. Enhancing analogic reasoning with rTMS over the left prefrontal cortex. Neurology 2001;56:526-528.38.Iyer MB, Mattu U, Grafman J, Lomarev M, Sato S, Wassermann EM. Safety and cognitive effect of frontal DC brain polarization in healthy individuals. Neurology 2005;64:872-875.39.Fregni F, Boggio PS, Lima MC, Ferreira MJ, Wagner T, Rigonatti SP, et al. A sham-controlled, phase II trial of transcranial direct current stimulation for the treatment of central pain in traumatic spinal cord injury. Pain 2006;122:197-209.AbstractEffects of non-invasive transcranial brain stimulationon the enhancement of cognitive function in normal personSuk Hoon OhnDepartment of MedicineThe Graduate School, Yonsei University(Directed by Professor Chang-Il Park)In the maintaining process of inputted information into the brain, it is called to working memory that makes the inputted information maintained for a seconds and plays a basic role of long term memory, language, and executive function. For the modulation of brain function, the noninvasive brain stimulation methods such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) were proved to be effective. Recently, for the enhancement of memory, these two methods are being massively investigated. However, the optimal site of stimulation or dose of stimulation for the enhancement of memory function is not well established. It is also not well investigated how long the stimulation effect is lasted after stimulation. The objectives of this study are to determine the effective stimulation site, dose, and residual effect of rTMS and tDCS for the enhancement of working memory. For these purpose, rTMS with the intensity of 100 % motor threshold and the frequency of 10Hz, and tDCS with 1 mA were applied in the twenty normal persons.The results of this study were as follow;1. After 1,000 pulses of real rTMS, the correct rate and accuracy were improved compared to the baseline and the previous test (p<0.05).2. rTMS effect was maintained for 30 minutes after the end of stimulation (p<0.05).3. The error rate and reaction time were not changed by rTMS.4. After 20 minutes of real tDCS, the correct rate and accuracy were improved compared to the baseline and the previous test (p<0.05). After 30 minutes of real tDCS, the correct rate and accuracy were improved compared to the previous test (p<0.05).5. tDCS effect was maintained for 30 minutes after the end of stimulation (p<0.05).6. The error rate and reaction time were not changed by tDCS.7. Side effect did not occur during or after rTMS and tDCS.With these results, both rTMS and tDCS were considered as effective and safe brain stimulation methods to enhance working memory in normal person. For the enhancement of verbal working memory by tDCS and rTMS, the left prefrontal cortex seemed to be a proper site of stimulation. By tDCS at 1mA, stimulation time more than 20 minutes was required, whereas by 10 Hz rTMS at the intensity of 100 % motor threshold, 1,000 pulses were needed to obtain the positive effect of stimulation.