Promoting neuroplasticity for functional restoration after spinal cord injury.
Hello, I'm Adele Field-Fote, PhD, PT,
Professor of Physical Therapy and Neurological Surgery,
and Principal Investigator, Miami Project to Cure Paralysis at the University of Miami,
Miller School of Medicine.
When we talk about neuroplasticity in terms of motor function,
we're talking about the capacity of the central nervous system to undergo changes
in function and structure in response to use and motor learning.
It's important to remember that this plasticity can
either be favorable or supportive of function,
in which case we say it's adaptive,
or it can be unfavorable and not support function,
in which case we say it's maladaptive.
Changes in synaptic efficacy are one mechanism underlying neuroplasticity.
Let's take a look at what happens in a cell to a typical stimulus
and how its resting state determines the response to that stimulus.
On the far left,
you see a cell sitting at
its typical membrane potential and its response to an incoming stimulus.
In the center is the response to that same stimulus
when the cell is in a depressed or hyperpolarized state.
On the right is the response to that same stimulus when
the cell is in a depolarized or relatively excited state.
By changing the state of the cell membrane potential,
we can change its responsiveness to stimuli.
Next, we'll look at how these responses communicate to the next cell in the system.
In the postsynaptic cell,
we see on the far left the response to
a typical input when the cell is sitting at its normal resting state.
The cell that's sitting at its hyperpolarized state in
the center results in a smaller response in the postsynaptic cell to that same input.
However, on the far right,
when the presynaptic cell is sitting in its relatively excited state,
it results in a larger response in the postsynaptic cell to that same input.
So by changing the activity of the nervous system and its level of excitability,
we can affect its responsiveness to stimuli or to voluntary commands.
Next, let's discuss how high levels of activity influence the nervous system.