Homeostatic modulation of stimulation-dependent plasticity in human motor cortex

Autor: Jelena Krstic, Sladjan Milanovic, Bajec Dd, Tihomir V. Ilić, Nela V. Ilić, Mirko Grajic
Rok vydání: 2011
Předmět:
Adult
Male
Time Factors
Physiology
Stimulation
Somatosensory system
03 medical and health sciences
Young Adult
0302 clinical medicine
Cortex (anatomy)
Evoked Potentials
Somatosensory
Motor system
medicine
Reaction Time
Homeostasis
Humans
Paired associative stimulation
Evoked potential
Muscle
Skeletal
030304 developmental biology
Motor Neurons
0303 health sciences
Neuronal Plasticity
Chemistry
Electromyography
musculoskeletal
neural
and ocular physiology
Interstimulus interval
Homeostatic plasticity
Motor Cortex
Long-term potentiation
General Medicine
Middle Aged
Evoked Potentials
Motor
Hand
Transcranial Magnetic Stimulation
Electric Stimulation
Median Nerve
medicine.anatomical_structure
Sensory Thresholds
Motor cortex
Female
Neuroscience
Serbia
Transcranial magnetic stimulation
030217 neurology & neurosurgery
Zdroj: Europe PubMed Central
Scopus-Elsevier
Physiological Research
ISSN: 1802-9973
Popis: Since recently, it is possible, using noninvasive cortical stimulation, such as the protocol of paired associative stimulation (PAS), to induce the plastic changes in the motor cortex, in humans that mimic Hebb's model of learning. Application of TMS conjugated with peripheral electrical stimulation at strictly coherent temporal manner lead to convergence of inputs in the sensory-motor cortex, with the consequent synaptic potentiation or weakening, if applied repetitively. However, when optimal interstimulus interval (ISI) for induction of LTP-like effects is applied as a single pair, Motor evoked potential (MEP) amplitude inhibition is observed, the paradigm known as short-latency afferent inhibition (SLAI). Aiming to resolve this paradox, PAS protocols were applied, with 200 repetitions of TMS pulses paired with median nerve electrical stimulation, at ISI equal to individual latencies of evoked response of somatosensory cortex (N(20)) (PAS(LTP)), and at ISI of N(20) shortened for 5 msec (PAS(LTD)) - protocols that mimic LTP-like changes in the human motor cortex. MEP amplitudes before, during and after interventions were measured as an indicator based on output signals originating from the motor system. Post-intervention MEP amplitudes following the TMS protocols of PAS(LTP) and PAS(LTD) were facilitated and depressed, respectively, contrary to MEP amplitudes during intervention. During PAS(LTP) MEP amplitudes were significantly decreased in case of PAS(LTP), while in the case of PAS(LTD) an upward trend was observed. In conclusions, a possible explanation for the seemingly paradoxical effect of PAS can be found in the mechanism of homeostatic modulation of plasticity. Those findings indicate the existence of complex relationships in the development of plasticity induced by stimulation, depending on the level of the previous motor cortex excitability.
Databáze: OpenAIRE
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