But first you'll need to read If You Give a Mouse a Cookie written by Laura Numeroff and illustrated by Felicia Bond
http://www.alphagalileo.org/ViewItem.aspx?ItemId=128235&CultureCode=en
“When you
grab a cookie and want to break off a piece with a chocolate chip,”
says Maurice Smith, balancing a crumbly bit between two of his fingers,
“your brain must represent that action plan extrinsically, as it is an activity based in the world.”
The cookies are on hand to celebrate the bioengineer’s birthday in
his lab at 60 Oxford Street, a white squat building located on the
northernmost edge of the Harvard campus. A half moon of chocolate cake
with a line of colored candles still intact also sits nearby.
Gesticulating with the cookie, Smith, Associate Professor of
Bioengineering at the Harvard School of Engineering and Applied Sciences
(SEAS), further teases out the intricacies of motor memory.
“An intrinsic representation is one that’s body-based and
procedural. It relates to the complex series of muscle and joint
movements your body has to make to complete a task,” Smith says.
“When I first had the thought to grab the cookie and rip off a chunk
with a chocolate chip, my body responded appropriately,” he notes.
Understanding the way the brain represents extrinsic and intrinsic
actions, and the relationship between the two, has been of great
interest to researchers who seek to understand motor control and motor
learning—or, put simply, how we learn to move.
Just a few months ago, Smith and his colleagues in the Neuromotor
Control Lab laid out a generalizable theory about how the brain encodes
such motor memories. Writing in the Journal of Neuroscience,
they showed that units of motor memory are not so binary after all, but
instead a mixture of both the intrinsic and the extrinsic.
“There’s no question that our actions are inherently spatial, but the
nature of the coordinate frame used in motor memory to represent space
for action planning has been hotly debated,” explains Smith. “The
predominant idea had been that in memory we maintain separate intrinsic
and extrinsic representations of action and translate between the two
when necessary. But our work shows that memory representations are
combinatorial rather than separate.”
Individual neurons in several different motor areas of the brain
encode multiplicative combinations of intrinsic and extrinsic
representations, a property that neurophysiologists have called
gain-field encoding. This much was known before, but it was thought that
gain-field encoding simply provided a way to translate between
intrinsic and extrinsic representations.
“We found that this gain-field encoding, which leads to a
combinatorial representation of space, is not simply an intermediary in
the transformation between representations, but is in fact the encoding
on which motor memories are based,” says Smith. “This suggests that the
neurons which display gain-field encoding are the same ones that store
the motor memories associated with the actions we learn.”
The study, seemingly abstract, plays right into Smith’s larger game
plan. He and his research group at SEAS are trying to figure out the
body’s motor system the way a mechanic would: that is, well enough to be
able to fix or temporarily repair it when it becomes damaged.
A neurodegenerative disorder resulting from a stroke or from a
condition like Alzheimer’s disease can make the act of picking up a
cookie nearly impossible. But how does one go from an abstract
theoretical model about encoding motor memory to something an engineer, a
person interested in designing and building actual stuff and collecting
real-world data about how we move, might more readily recognize?
The answer lies in a simple room slightly bigger than a walk-in
closet. Near the entrance to Smith’s lab, an alcove space is outfitted
with a table, a monitor, an adjustable barber chair, and a digital pen
and pad. The simple setup allows Smith and his team to record movements
and to train participants to make hand motions based on visual cues.
Smith’s lab is one of the few at SEAS that relies on human trials. In
the facilities surrounding his, engineers have built tiny robotic
insects, lungs-on-a-chip, and an artificial jellyfish made of a rat’s
heart tissue and silicone. Yet, despite its name, the work at the
Neuromotor Control Lab seems far removed from the snap, crackle, and pop
of actual neurons, as there are no neural head meshes or electrodes in
sight. There are no brains in jars or neural tissue strands in glass
petri dishes. Smith, who has an M.D. as well as a Ph.D. from Johns
Hopkins, spends considerable time explaining how it all makes sense.
In the case of this new theory about intrinsic and extrinsic action,
Smith’s motion recording setup provides a simple yet powerful means to
collect large amounts of data—millions of individual movements—that
elucidate the algorithms and neural representations by which we learn to
control our actions.
Jordan Brayanov, a graduate student at SEAS, excitedly explains where
all of this work is ultimately headed: helping those suffering from
brain injury.
“You cannot break real human brains for science, and it is difficult
to work with patients who are already exhibiting cognitive deficits, so
our lab is set up to mimic these conditions in healthy people—in our
case, a lot of Harvard undergraduates,” says Brayanov. “Understanding
how our bodies learn to reach and grasp provides us with insights about
how the nervous system works. Just as importantly, we can start to see
what may be happening when it’s not working, when a person has some kind of motor disorder as a result of neurologic disease.”
Motor dysfunction remains one of the most debilitating of health
problems, and it is often the hidden deal breaker behind the nursing
home placement and loss of independence for patients with Alzheimer’s,
which most people associate with declining mental abilities and deficits
in declarative memories rather than motor skills.
“It’s actually not so much the declarative memory loss that leads to
having to institutionalize someone with Alzheimer’s, but the inability
to do the most basic motor tasks, like dressing or eating,” explains
Smith.
Armed with new insights from the lab, Smith and his team can offer
guidance to others who are developing new ways to treat motor problems.
They’re placing their hope in noninvasive techniques that use
magnetic fields or direct current to selectively increase or decrease
the neural plasticity of isolated populations of neurons—no skull
drilling required.
“These techniques have shown some promise for potentially boosting
selective neural activity to stave off the onset of motor deficits,”
says Brayanov. “They’re relatively crude right now. They can’t yet zero
in with millimeter accuracy on specific brain areas, but they will get
better and better.”
Therapeutic success, however, also requires clinicians to know which neurons to stimulate, and when.
In essence, Smith, Brayanov, and their colleagues are trying to write
part of the instructional manual that doctors will one day use to help
combat neurodegenerative diseases, much in the same way other engineers
might provide the schematics for an artificial hand.
“If we can do that, we can potentially provide a boost in quality of
life as well as a savings in healthcare expenditure,” says Smith. “Even
if it only means staving off a motor deficit for six months, in the case
of a progressive neurodegenerative disease like Alzheimer’s, that’s
still six months more of independent living.”
This work was supported by grants from the McKnight Endowment for
Neuroscience, the Alfred P. Sloan Foundation, and the Wallace H. Coulter
Foundation.
https://www.seas.harvard.edu/news-events/press-releases/if-you-give-a-bioengineer-a-cookie
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Changing stroke rehab and research worldwide now.Time is Brain! trillions and trillions of neurons that DIE each day because there are NO effective hyperacute therapies besides tPA(only 12% effective). I have 523 posts on hyperacute therapy, enough for researchers to spend decades proving them out. These are my personal ideas and blog on stroke rehabilitation and stroke research. Do not attempt any of these without checking with your medical provider. Unless you join me in agitating, when you need these therapies they won't be there.
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