Quadripulse stimulation (QPS): a new plasticity induction method in humans

[Speaker] Ugawa, Yoshikazu:1
1:Fukushima Medical University (Japan)

We have proposed QPS to be a powerful long lasting effects (LTP/LTD like effects) inducing method in humans.
What's QPS?
In QPS, one train of four monophasic TMS pluses separated by different inter-stimulus intervals (ISIs) was given every 5 seconds for 30 minutes. The short interval QPS induced a LTP like effect and the long interval QPS induced a LTD like effect. The physiological changes induced by QPS were all compatible with those seen in synaptic plasticity.
Dopamine/Dopamine agonist/Zonisamide and plasticity
We compared LTP/LTD effect between baseline condition and the condition after L-Dopa intake in normal volunteers. Dopamine enhanced both LTP and LTD. In contrast, dopamine agonists had no significant influence on LTP/LTD like effects. Zonisamide mildly enhanced LTP like effect.
Neuroplasticity in PD
In PD patients, QPS induced neither LTP nor LTD like effects in the motor cortex. This lack of plasticity was normalized by L-DOPA intake.
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