Modulation of the Direction and Magnitude of Hebbian Plasticity in Human Motor Cortex by Stimulus Intensity and Concurrent Inhibition

Autor: Robin F.H. Cash, Gaayathiri Jegatheeswaran, Zhen Ni, Robert Chen
Rok vydání: 2016
Předmět:
Adult
Male
Intensity
Plasticity
medicine.medical_treatment
Long-Term Potentiation
Biophysics
Individuality
Stimulation
Stimulus (physiology)
Somatosensory system
050105 experimental psychology
lcsh:RC321-571
03 medical and health sciences
Young Adult
0302 clinical medicine
Evoked Potentials
Somatosensory
Neuroplasticity
medicine
Reaction Time
Humans
Learning
0501 psychology and cognitive sciences
Paired associative stimulation
lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry
Neuronal Plasticity
Spike-timing-dependent plasticity
Electromyography
musculoskeletal
neural
and ocular physiology
General Neuroscience
Interstimulus interval
05 social sciences
Motor Cortex
Long-term potentiation
Neural Inhibition
Middle Aged
Evoked Potentials
Motor
Transcranial Magnetic Stimulation
Median Nerve
Transcranial magnetic stimulation
Short latency afferent inhibition
Female
Neurology (clinical)
Psychology
Neuroscience
030217 neurology & neurosurgery
Zdroj: Brain Stimulation, Vol 10, Iss 1, Pp 83-90 (2017)
ISSN: 1876-4754
Popis: Background The mechanisms mediating the efficacy and variability of paired associative stimulation (PAS), thought to be mediated by Hebbian plasticity, remain incompletely understood. The magnitude and direction of Hebbian plasticity may be modulated by the level of neural depolarisation, which is influenced by stimulation intensity and interactions with cortical circuits. Hypothesis PAS effects would be influenced by the intensity of transcranial magnetic stimulation (TMS) and interaction with other circuits. In particular, PAS would be inhibited by concurrent inhibitory input following median nerve stimulation, known as short latency afferent inhibition (SAI). Methods PAS was tested at an interstimulus interval (ISI) 2 ms or 6 ms longer than the N20 peak of the median nerve somatosensory-evoked potential (PAS N20+2 , PAS N20+6 ). PAS N20+2 was tested at three different TMS intensities. Short interval intracortical facilitation and inhibition were tested in the presence of SAI (SICF SAI , SICI SAI ). Results The propensity for long term potentiation like effects increased with higher PAS N20+2 TMS stimulus intensity, whereas long term depression like effects ensued at subthreshold intensity. Stronger SAI correlated with weaker PAS LTP-like effects across individuals. PAS N20+2 (maximal SAI) was less effective than PAS N20+6 (weak SAI). SICF SAI or SICI SAI did not influence PAS response. Conclusion Inter-individual differences in SAI contribute to the variability in PAS efficacy. The magnitude and direction of PAS effects is modulated by TMS intensity. Together, these findings indicate that the level of neural activity induced by stimulation likely plays a crucial role in determining the direction and magnitude of Hebbian plastic effects evoked by PAS in human cortex.
Databáze: OpenAIRE
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