A Temporally Asymmetric Hebbian Rule Governing Plasticity in the Human Motor Cortex

2003 ◽  
Vol 89 (5) ◽  
pp. 2339-2345 ◽  
Author(s):  
Alexander Wolters ◽  
Friedhelm Sandbrink ◽  
Antje Schlottmann ◽  
Erwin Kunesch ◽  
Katja Stefan ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Median Nerve ◽  
Cortical Excitability ◽  
Long Term Potentiation ◽  
Long Term Depression ◽  
Human Motor Cortex ◽  
Motor Cortical Excitability ◽  
Human Motor ◽  
Motor Cortical

Synaptic plasticity is conspicuously dependent on the temporal order of the pre- and postsynaptic activity. Human motor cortical excitability can be increased by a paired associative stimulation (PAS) protocol. Here we show that it can also be decreased by minimally changing the interval between the two associative stimuli. Corticomotor excitability of the abductor pollicis brevis (APB) representation was tested before and after repetitively pairing of single right median nerve simulation with single pulse transcranial magnetic stimulation (TMS) delivered over the optimal site for activation of the contralateral APB. Following PAS, depression of TMS-evoked motor-evoked potentials (MEPs) was induced only when the median nerve stimulation preceded the TMS pulse by 10 ms, while enhancement of cortical excitability was induced using an interstimulus interval of 25 ms, suggesting an important role of the sequence of cortical events triggered by the two stimulation modalities. Experiments using F-wave studies and electrical brain stem stimulation indicated that the site of the plastic changes underlying the decrease of MEP amplitudes following PAS (10 ms) was within the motor cortex. MEP amplitudes remained depressed for approximately 90 min. The decrease of MEP amplitudes was blocked when PAS(10 ms) was performed under the influence of dextromethorphan, an N-methyl-d-aspartate-receptor antagonist, or nimodipine, an L-type voltage-gated calcium-channel antagonist. The physiological profile of the depression of human motor cortical excitability following PAS(10 ms) suggests long-term depression of synaptic efficacy to be involved. Together with earlier findings, this study suggests that strict temporal Hebbian rules govern the induction of long-term potentiation/long-term depression-like phenomena in vivo in the human primary motor cortex.

Paired-pulse measures

2012 ◽  
Author(s):  
Ritsuko Hanajima ◽  
Yoshikazu Ugawa
Keyword(s):  
Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potential ◽  
Paired Pulse ◽  
Motor Cortical Excitability ◽  
Interhemispheric Connectivity ◽  
Conditioned Motor ◽  
Human Motor ◽  
Motor Cortical ◽  
Insight Into

This article reviews the physiology and application of the currently available paired-pulse protocols. Paired-pulse transcranial magnetic stimulation (TMS) techniques study the modulation of human motor cortical excitability. Paired-pulse experiments are designed to give insight into the nature of the cortical circuitry activated by TMS. Changes in motor cortical excitability produced by the conditioning pulse are estimated by changes in the size of the conditioned motor-evoked potential (MEP). It is possible to identify specific abnormalities in the balance between inhibitory and facilitatory processes, even if the pathology lies in abnormal afferent signalling to the motor cortex rather than in the motor cortex itself. The conclusion that emerges from the studies on interhemispheric interactions is that it is now possible by means of TMS protocols to chart long-range functional interhemispheric connectivity of remote areas of the human brain.

146. Preceding repetitive stimulation diminishes long-term potentiation-like plasticity in human motor cortex

2009 ◽  
Vol 120 (1) ◽  
pp. e61
Author(s):  
I. Delvendahl ◽  
N. Jung ◽  
M. Cronjaeger ◽  
F. Mainberger ◽  
N. Kuhnke ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Long Term Potentiation ◽  
Repetitive Stimulation ◽  
Human Motor Cortex ◽  
Term Potentiation ◽  
Human Motor

Inducing Homeostatic-Like Plasticity in Human Motor Cortex Through Converging Corticocortical Inputs

2009 ◽  
Vol 102 (6) ◽  
pp. 3180-3190 ◽  
Author(s):  
Monika Pötter-Nerger ◽  
Sarah Fischer ◽  
Claudia Mastroeni ◽  
Sergiu Groppa ◽  
Günther Deuschl ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Median Nerve ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Long Term Potentiation ◽  
Corticospinal Excitability ◽  
Human Motor Cortex ◽  
Induced Changes ◽  
Homeostatic Response

Transcranial stimulation techniques have revealed homeostatic-like metaplasticity in the hand area of the human primary motor cortex (M1HAND) that controls stimulation-induced changes in corticospinal excitability. Here we combined two interventional protocols that induce long-term depression (LTD)–like or long-term potentiation (LTP)–like plasticity in left M1HAND through different afferents. We hypothesized that the left M1HAND would integrate LTP- and LTD-like plasticity in a homeostatic fashion. In ten healthy volunteers, low-intensity repetitive transcranial magnetic stimulation (rTMS) of the left dorsal premotor cortex (PMD) was first applied to produce an LTP-like increase (5 Hz rTMS) or LTD-like decrease (1 Hz rTMS) in corticospinal excitability in left M1HAND via premotor-to-motor inputs. Following PMD rTMS, paired-associative stimulation (PAS) was applied to the right median nerve and left M1HAND to induce spike-time–dependent plasticity in sensory-to-motor inputs to left M1HAND. We adjusted the interstimulus interval to the N20 latency of the median nerve somatosensory-evoked cortical potential to produce an LTP-like increase (PASN20+2ms) or an LTD-like decrease (PASN20−5ms) in corticospinal excitability. The amplitude of motor-evoked potentials was recorded from intrinsic hand muscles to assess stimulation-induced changes in corticospinal excitability. Premotor-to-motor preconditioning triggered a homeostatic response to subsequent sensory-to-motor PAS. After facilitatory 5 Hz rTMS, “facilitatory” PASN20+2ms suppressed corticospinal excitability. Likewise, “inhibitory” PASN20−5ms facilitated corticospinal excitability after “inhibitory” 1 Hz rTMS. There was a negative linear relationship between the excitability changes induced by PMD rTMS and those elicited by subsequent PAS. Excitability changes were not paralleled by changes in performance during a finger-tapping task. These results provide evidence for a homeostatic response pattern in the human M1HAND that integrates acute plastic changes evoked through different “input channels.”

Exploring the effect of inducing long-term potentiation in the human motor cortex on motor learning

2011 ◽  
Vol 4 (3) ◽  
pp. 137-144 ◽  
Author(s):  
Tarek K. Rajji ◽  
Shi-Kai Liu ◽  
Marina V. Frantseva ◽  
Benoit H. Mulsant ◽  
Jessica Thoma ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Motor Learning ◽  
Long Term Potentiation ◽  
Human Motor Cortex ◽  
Term Potentiation ◽  
Human Motor

Mechanisms of human motor cortex facilitation induced by subthreshold 5-Hz repetitive transcranial magnetic stimulation

2013 ◽  
Vol 109 (12) ◽  
pp. 3060-3066 ◽  
Author(s):  
Martin Sommer ◽  
Milena Rummel ◽  
Christoph Norden ◽  
Holger Rothkegel ◽  
Nicolas Lang ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Long Term Potentiation ◽  
Human Motor Cortex ◽  
Term Potentiation ◽  
Human Motor ◽  
Extensor Carpi Radialis

Our knowledge about the mechanisms of human motor cortex facilitation induced by repetitive transcranial magnetic stimulation (rTMS) is still incomplete. Here we used pharmacological conditioning with carbamazepine, dextrometorphan, lorazepam, and placebo to elucidate the type of plasticity underlying this facilitation, and to probe if mechanisms reminiscent of long-term potentiation are involved. Over the primary motor cortex of 10 healthy subjects, we applied biphasic rTMS pulses of effective posterior current direction in the brain. We used six blocks of 200 pulses at 5-Hz frequency and 90% active motor threshold intensity and controlled for corticospinal excitability changes using motor-evoked potential (MEP) amplitudes and latencies elicited by suprathreshold pulses before, in between, and after rTMS. Target muscle was the dominant abductor digiti minimi muscle; we coregistered the dominant extensor carpi radialis muscle. We found a lasting facilitation induced by this type of rTMS. The GABAergic medication lorazepam and to a lesser extent the ion channel blocker carbamazepine reduced the MEP facilitation after biphasic effective posteriorly oriented rTMS, whereas the N-methyl-d-aspartate receptor-antagonist dextrometorphan had no effect. Our main conclusion is that the mechanism of the facilitation induced by biphasic effective posterior rTMS is more likely posttetanic potentiation than long-term potentiation. Additional findings were prolonged MEP latency under carbamazepine, consistent with sodium channel blockade, and larger MEP amplitudes from extensor carpi radialis under lorazepam, suggesting GABAergic involvement in the center-surround balance of excitability.

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