Browsing by Author "Hodzic, Kenan"

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    A Methodological Study Comparing Two Motor Cortex Plasticity Paradigms in Healthy Adults
    (2020-09-28) Hodzic, Kenan; University of Gothenburg / Institute of Medicine; Göteborgs universitet / Institutionen för medicin
    Background: Neural plasticity is an important function of the brain allowing for change in synaptic transmissions. Modulation in plasticity arises through activity-dependent strengthening; long-term potentiation (LTP), or weakening; long-term depression (LTD), of synaptic transmissions. Such plasticity may be induced by repeated pairing of transcranial magnetic stimulation (TMS) to the human motor cortex, with peripheral median nerve stimulation (PNS), a method called paired associative stimulation (PAS). PAS induces LTP-like (i.e. PASLTP) or LTD-like (i.e. PASLTD) cortical changes in excitability, measured as motor evoked potentials (MEPs) using electromyography (EMG) of the targeted hand muscle. Aims: In order to utilize the PAS-method to investigate aberrant neuroplasticity in pathologies, we compared two well-established PAS-paradigms regarding their capacity to induce either PASLTP or PASLTD, the impact of time efficiency and frequency of reported adverse events. Methods: In the present double-blinded, crossover study we compared two different PAS-paradigms in 14 healthy subjects: 180 paired TMS + PNS stimulations (PAS-180) at 0.1Hz and 225 paired TMS + PNS stimulations (PAS-225) at 0.25Hz. Each paradigm consisted of two protocols: PASLTP utilizing an interstimulus interval (ISI) between pairings of 25ms inducing increased excitability, and PASLTD utilizing an ISI of 10ms inducing decreased excitability. Results: Responders were defined as having a grand mean of MEPs larger than the averaged baseline for PASLTP, and a lower grand mean of MEPs for PASLTD. Both paradigms successfully induced PASLTP in responders (N=9), however no PASLTD effects were found in either paradigm. PAS-225 had a lower frequency of reported adverse events and was more time efficient. Conclusions: Both paradigms induced equivalent PASLTP effects in subjects. Due to PAS-225 being more time efficient and associated with less reported adverse events, it is seen as preferential and will be used in future studies examining neural plasticity.