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academies
17
th
International Conference on
4
th
International Conference on
NEUROLOGY AND NEUROSCIENCE
&
MENTAL HEALTH AND PRIMARY CARE
October 16-18, 2017 | Toronto, Canada
J Neurol Neurorehabil Res 2017 | Volume 2 Issue 3
Promoting neural plasticity in human sensorimotor cortex to alter activity in upper limb muscles
Aimee J Nelson
McMaster University, Canada
M
y research aims to determine the mechanisms that
mediate plasticity in the human sensorimotor cortex,
as a novel means to alter the motor cortical output to skeletal
muscles and influence the motor control of the upper
limb. There are two forms of plasticity that are considered
complimentary and fundamental to neural systems.
Homosynaptic plasticity changes the efficiency of synapses
that are themselves active during the induction of plasticity,
a mechanism thought to underpin learning and memory
formation. Heterosynaptic plasticity changes the efficiency of
synapses because of input from another pathway to support
learning through stabilizing synaptic weights. Transcranial
magnetic stimulation (TMS) is a technique capableof inducing
either hetero- or homosynaptic plasticity. Heterosynaptic
plasticity is induced following repeat pairing of electrical
stimulation of a peripheral nerve with single TMS pulses over
the primary somatosensory (S1) nerve or primarymotor (M1)
cortex muscle representation. Heterosynaptic plasticity is
induced using a protocol called rapid-rate Paired Associative
Stimulation (rPAS) that delivers 600 nerve-TMS pairs at a
rate of 5 Hz. RPAS induces long-term potentiation (i.e. neural
plasticity) effects when the nerve-TMS interstimulus interval
(ISI) is set to promote their coincident arrival in S1, based
on the N20 latency of the somatosensory evoked potential
(SEP). RPAS promotes long-term depression at ~ 10 ms
ISI. Homosynaptic plasticity is achieved using 600 pulses
continuous theta-burst stimulation (cTBS) and intermittent
theta-burst stimulation (iTBS) to evoke long-term depression
and potentiation effects, respectively. In this talk, I will
describe evidence from recent publications and advances
frommy lab that use TMS protocols of RPAS and TBS to evoke
neural plasticity in human sensorimotor cortex. The primary
purpose of these approaches is to alter the neural output
to muscles of the arm. This research indicates that different
methods for inducing human neural plasticity in cortex
yield varying results on the corticospinal excitability of arm
muscles. This information provides information fundamental
to creating new rehabilitation regimes that aim to improve
arm movement following disease and neurological injury.
Speaker Biography
Aimee J Nelson is an Associate Professor in the Department of Kinesiology at
McMaster University. She has completed her PhD at the Institute of Medical Sciences,
the University of Toronto. She received her first Post-doctoral appointment at the
McGovern Institute for Brain Research, MIT, and was subsequently a CIHR-funded Post-
doctoral fellow at Toronto Western Hospital. Her academic appointment began in 2008
at the University of Waterloo and she subsequently joined McMaster University in
2012 as a Canada Research Chair, Tier 2. Her research is focused on promoting neural
plasticity in brain and spinal cord for altering hand control. Her research is in basic
neurophysiology and neuroimaging and her research has application in neurological
injury and disease wherein hand/arm control is impaired. Her technical expertise
includes transcranial magnetic stimulation, functional, anatomical and spectral
imaging, and electroencephalography.
e
:nelsonaj@mcmaster.ca