Depression of motor cortex excitability by low-frequency transcranial magnetic stimulation

“As suggested, this effect might be similar to the phenomenon of long-term potentiation and long-term depression) observed in animals.([14]) The other predictor that was associated with the duration of rTMS antidepressant effects was age; such as that younger patients had a larger remission time.”

“higher changes cortical excitability (Chen et al., 1997).”

“Following a 1 Hz rTMS [which has been shown to reduce cortical excitability for minutes afterward (Chen et al 1997)], subjects were asked to visualise and memorise sets of stripes, which varied in length, width, orientation, and distance between stripes, and to compare properties (eg relative…”

“Consequently, the decreased excitability of Broca's area after rTMS (Shapiro et al., 2001; Maeda et al., 2000; Pascual-Leone et al., 1999; Chen et al., 1997) could not reach the threshold to interfere visibly with the responses to audiovisual word presentation.”

“This effect has been demonstrated neurophysiologically in the motor cortex (Chen et al., 1997) and confirmed behaviorally for various cortical areas, including the sensory cortices (Kosslyn et al., 1999; Boroojerdi et al., 2000; Knecht et al., 2003).”

“Trains of low-frequency stimulation (<1 Hz) induce a reduction in motor cortex excitability demonstrated by a decrease in motor-evoked potential (MEP) amplitudes (19, 20), providing a rationale for exploring low-frequency rTMS as treatment for epilepsy.”

“…work using repetitive transcranial stimulation has shown that it is also possible to produce lasting effects on physiology and behaviour in humans that may involve changes in synaptic function within the brain (Chen et al. 1997; Nitsche & Paulus, 2000; Stefan et al. 2000; Peinemann et al. 2004).”

“Low-frequency rTMS reduces motor cortex excitability (75).”

“A wide range of transcranial stimulation protocols are capable of inducing lasting changes in corticospinal excitability in healthy human volunteers [3], including continuous or patterned repetitive transcranial magnetic stimulation (rTMS) [4,5,6], paired associative stimulation (PAS) [7,8], continuous or oscillatory…”

“High-frequency repetitive TMS (5–20Hz) has been shown to increase cortical excitability whereas low frequency (1Hz) repetitive TMS decreases cortical excitability (Chen et al., 1997; Pascual-Leone et al., 1994).”

“Empirical evidence has indicated that continuous rTMS below 1 Hz reduces cortical excitability, whereas intermittent rTMS trains above 5 Hz have the opposite effect (Pascual-Leone et al., 1994; Chen et al., 1997; Maeda et al., 2000).”

“TMS pulses were delivered at a frequency of 0.1–0.2 Hz for all TMS protocols to avoid long lasting modulation of M1 excitability (Chen et al., 1997).”

“…evoked potential after stimulation of the motor cortex), rTMS delivered for a duration of minutes at a low frequency (0.5–2 Hz) tends to decrease resting corticospinal excitability, whereas higher frequencies (>5 Hz) tend to increase resting excitability (Chen et al., 1997; Maeda et al., 2000).”

“, 1998) while at low frequencies (r1 Hz) it suppresses cortical excitability (Chen et al., 1997).”

“002 beyond the duration of the rTMS (Pascual-Leone et al., 1998; Chen et al., 1997; Touge et al., 2001).”

“Low-frequency rTMS at 1 Hz applied to the human motor and visual cortices for 15 min was shown to produce inhibitory effects and the effect lasted at least 15 and 10 min, respectively.(13,14) Each stimulus session in the present study, which lasted 250 s, might have been too short to produce a sufficient inhibitory ef…”

“78, 364–396 120 Chen, R. et al. (1997) Depression of motor cortex excitability by low-frequency transcranial magnetic stimulation. Neurology 48, 1398–1403 121 Boroojerdi, B. et al. (2000) Reduction of human visual cortex excitability using 1Hz transcranial magnetic stimulation. Neurology 11, 1529–1531 122 Rossi, S. et…”

“…motor cortical structures, with lowfrequency rTMS (LF-rTMS 1 Hz) having an inhibitory effect generally leading to decreased cortical excitability (Chen et al. 1997; Pascual-Leone et al. 1998) and high-frequency rTMS (HF-rTMS 1 Hz) having an excitatory effect (Pascual-Leone et al. 1998; Speer et…”

“Similar effects of increased or decreased excitability dependent on TMS frequency were originally found in motor cortex (63, 64).”

“Generally 5- to 10-s intervals ought to be used (Chen et al. 1997).”

“In humans, Chen et al. (1997) studied for the first time the effects of low frequency rTMS on motor cortex excitability.”

“, 1 Hz rTMS) has been shown to reduce excitability of the cortex (Chen et al., 1997).”

“Given this previous literature, in our study interference was applied simultaneously with memory reactivation and the behavioral and connectivity effects of such interference were measured the following day, long after dissipation of the rTMS neurophysiological aftereffects (Chen et al., 1997; Cheeran et al., 2010; Ei…”

“modulation of cortical neuronal circuits beyond the time of magnetic stimulation itself.(28,29) The assessment of how a treatment affects daily life is of critical importance in establishing its clinical relevance.”

“inhibit neural activity around the simulated area (Chen et al., 1997), whereas high stimulation frequencies (>5 Hz) increase the corticocortical excitability, i.”

“increased the RMT and reduction of the MEP input–output curve) for at least 15 min after the end of the stimulation (Chen et al. 1997a; Muellbacher et al. 2000). Low-frequency rTMS at intensities below RMT have a much weaker effect on corticospinal excitability than supra-threshold rTMS. Fitzgerald et al. (2002) appli…”

“Studies have shown that highfrequency rTMS had the role of local neuronal activity facilitatory, thereby increasing the excitability of the cerebral cortex, and low-frequency rTMS had the role of local neuronal activity inhibition that would reduce the excitement of cortexl (Chen et al. 1997).”

“It is used to study the central motor pathways [6], to map motor and cognitive functions, to study neural networks, and to modulate brain function with a potential therapeutic aim [7], [8].”

“RTMS modulates cortical excitability, with highfrequency (≥5 Hz) rTMS being facilitatory (PascualLeone, Valls-Sole, Wassermann, & Hallett, 1994) and low-frequency (≤1 Hz) rTMS being inhibitory (R. Chen et al., 1997).”

“This is in keeping with physiological studies showing that low-frequency (below 1 Hz) TMS does not induce changes in cortical excitability and therefore has no long-lasting neuromodulatory effects (22).”

“Because rTMS can modulate brain activity (20, 35), this therapy might induce similar brain effects compared to those of speech therapy, but through a central approach , suggesting, in addition, that the combination of speech therapy – such as with LSVT – and rTMS might increase the beneficial effects of speech therapy…”

“Low- or high-frequency stimulations, respectively, decrease or increase cortical excitability for some time in a way reminiscent of long-term depression (LTD) and long-term potentiation (LTP) (45,46).”

“The mechanism of inhibition of MEPs after lowfrequency rTMS is not clear, although analogies with long term depression have been proposed (Chen et al., 1997).”

“There have been numerous studies so far, using various modalities of sham transcranial stimulation, from early studies with repetitive TMS [31,32] to the latest attempts with transcranial static magnetic field stimulation [33], that have never shown any consistent change in motor cortex excitability following applicat…”

“Furthermore, motor cortex studies suggest that high and low frequency rTMS have opposite effects on the excitability of neurones in brain cortex [30,31].”

“MT probes membranerelated intrinsic neuronal excitability, given that MT is influenced by drugs that affect voltage-gated sodium and calcium channels (Ziemann et al., 1996a; Chen et al., 1997b).”

“1 Hz frequency did not induce any change in excitability (Chen et al., 1997).”

“Low frequency rTMS (stimulus rates r1Hz) produces a lasting decrease in motor cortex excitability [9].”

“Several studies showed consistently that rTMS for 15–30 min with a frequency of 1 Hz and an intensity of 115% resting motor threshold (RMT) produces a reduction in MEP amplitude of the stimulated M1 for at least 15 min (Chen et al. 1997; Siebner et al. 1999; Muellbacher et al. 2000; Gilio et al. 2003; Plewnia et al. 2…”

“Time interval between TMS pulses was at least 7500 ms to avoid cumulative effects of the stimulation (Chen et al., 1997).”

“Chen et al. (1997a) demonstrated that a 15-min train of supra-threshold 0.9 Hz rTMS applied to the M1 reduced MEP size for at least 15 min after the end of stimulation.”

“Conventional wisdom suggests that low-frequency ( 1 Hz) stimulation decreases cortical excitability, whereas high-frequency ( 1 Hz) stimulation increases excitability when applied to primary motor cortex (Pascual-Leone et al., 1994; Jennum et al., 1995; Chen et al., 1997; Berardelli et al., 1999).”

“It was shown that long trains of rTMS, applied over motor cortex, at frequencies at around 1 Hz result in a decrease of resting corticospinal excitability whereas high-frequency (5–20 Hz) rTMS trains usually lead to an increase in excitability (Chen et al. 1997; Maeda et al. 2000a, b).”

“This number of 1-Hz pulses has been shown to produce a significant reduction of excitability in the neural tissue at which it is directed [26].”

“…failed to evoke significant changes in regional cerebral blood flow (rCBF) during task performance at the site of stimulation despite physiological evidence that this protocol of stimulation decreases excitability (Chen et al., 1997; Maeda et al., 2000; Touge et al., 2001; Rizzo et al., 2004).”

“The prevailing hypothesis is that rTMS may stimulate neural activity in certain brain regions by modulating the balance between excitatory and inhibitory neurons [8-12].”

“The 1 Hz frequency is normally used to reduce the excitability of the motor cortex, as demonstrated by a reduction of the size of the motor evoked potentials (MEPs) following its application over the primary motor cortex (Chen et al., 1997).”

“More specifically, it has been demonstrated that rTMS selectively reduces the excitability of the motor cortex for roughly 15 min following treatment (Chen et al., 1997).”

“In this section, we discuss simultaneous timing between neurorehabilitation therapies, assessing muscle activitydependent stimulation, brain state-dependent stimulation, and simultaneous combination neurorehabilitation therapies.”

“1Hz) has no plasticity inducing effect on the human motor cortex (Chen et al., 1997; Ziemann et al., 1998a).”

“, 1994), while decreases in excitability have been shown not only in the motor cortex, but also in the visual cortex, if low-frequency (61 Hz) trains are given for 5 min or more (Chen et al., 1997; Boroojerdi et al., 2000; Cantello et al., 1991; Maeda et al., 2000; Muellbacher et al., 2000).”

“It has been reported that low-frequency rTMS of ≤1 Hz suppresses while high-frequency rTMS of ≥10 Hz activates local neural activities (Chen et al., 1997; Maeda, Keenan, Tormos, Topka, & Pascual-Leone, 2000; Rothwell, 1997).”

“Since low frequency rTMS has inhibitory effects when applied to motor cortex (Chen et al., 1997), this latter approach appears to be based on the hypothesis that inhibition of right pre-frontal cortex with low frequency rTMS might have the same therapeutic effect as excitation of left pre-frontal cortex.”

“…plasticity, it can be used to induce movement-specific M1 plasticity, rather than generalized increase/decrease of M1 plasticity induced by rTMS (Chen et al., 1997; Wu et al., 2000; Gilio et al., 2003; Quartarone et al., 2005) or DCS (Nitsche and Paulus, 2000, 2001; Nitsche et al., 2003), which…”

“After the response, the screen appeared black for 4–6 s, ensuring an inter-pulse interval greater than 10 s and thereby avoiding changes in motor excitability due to TMS per se [62].”

“…the custom chinrest to help keep participants’ head still during the delivery of TMS. Pulses were delivered at a rate of 1 Hz for 20 minutes, which has the effect of decreasing neural responses in the targeted area for at least 15 minutes following the cessation of stimulation (Chen et al., 1997).”

“THI 51 (40-70) 43 (28-66) 47 (30-62) 45 (34-66) BSI-18 3.”

“LTD was thus proposed as a putative cause of the changes seen in cortical excitability after low-frequency rTMS (Chen et al., 1997).”

“…Vicario, Bangor, UK Alkomiet Hasan, Ludwig-Maximilians-University Munich, Germany *Correspondence: Alvaro Pascual-Leone, Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, 330 Brookline Ave., Boston, MA 02215, USA e-mail:…”

“One of the first and still most commonly used protocols in human studies is low-frequency (around 1 Hz) rTMS. Chen et al. (1997) found that corticospinal excitability was reduced for 15 min after applying 0.9 Hz rTMS for the preceding 15 min, and speculated that this was due to long-term depression…”

“[29], in a study evaluating the effect of TMS on motorcortex excitability in humans, found that 1 h TMS stimulation with a frequency of 0.”

“, reduced MEP amplitudes) for a further 15 min after the end of repetitive (Chen et al. 1997; Möttönen and Watkins 2009).”

“That is, individual rTMS trains applied during seizures in this study were generally <2 min in duration, and were not long enough to expect a reduction in excitability that is seen after low frequency rTMS typically delivered for longer periods (Chen et al., 1997; Gangitano et al., 2002; Daskalakis et al., 2006; Fitzg…”

“Its mechanisms of action are unclear and to date studies have mainly tried to define rTMS effects by evaluating changes in motor cortex excitability using single and paired pulse magnetic stimulation (PascualLeone et al. 1994, 1998; Chen et al. 1997; Berardelli et al. 1998; Maeda et al. 2000; Peinemann et al. 2000; Ge…”

“Moreover, previous studies have demonstrated the potential modulatory effects of repetitive transcranial magnetic stimulation (rTMS) on the excitability of cortical neurons, depending on stimulus intensity (SI), frequency, or total number of stimulations [1–4].”

“Several studies have now shown that chronic low-frequency stimulation of the motor cortex can produce inhibitory intermediate-term effects (lasting for several minutes) after stimulation [28,29].”