You microwaved a sausage and egg Cuban from
Port Tampa for breakfast. Conversation at the breakfast table during breakfast
was very unusual for you. The sisters are readying to go to the pool. –
Amorella
Rather
than exercises you ‘bicycled’ in the pool for more than thirty minutes and
added supplemental hand paddling along the way. You had lunch (you ate half a
turkey sandwich and an Irish Whiskey cake and cream dessert). Each sister had
something different but each also got a dessert. Presently they are chatting in
the living room. You are ready for a nap after an exhausting last night. –
Amorella
1409
hours. Carol has always made me tired. Sometimes life is hard, sometimes it
isn’t. Nothing new one way or the other. I read a short article today about how
science can show the direction a person is going to go (through brain scans)
before the person knows this consciously. This is a similar article.
** **
Left or Right? The Brain Knows
Before You Move
Neuroscience News
February 26, 2015 Featured,
Neuroscience,
Neuroscience
Videos
Scientists at Janelia Research Campus have identified a neural
circuit that connects motor planning to movement.
With half a second’s planning, an animal’s brain prepares it to
quickly and precisely execute complex movements. Scientists at Howard Hughes
Medical Institute’s Janelia Research Campus have identified a neural circuit
that transforms the flurry of activity that occurs during this preparatory
period into commands that direct muscle movements.
The research by the Janelia scientists explains why injuries
that disrupt the brain’s ability to carry out movement planning typically
impair a person’s ability to make movements on just one side of his or her
body. Janelia group leader Karel Svoboda and his colleagues reported their
findings in the February 26, 2014 issue of the journal Nature.
Neurons in the brain’s premotor cortex are active during the
planning period that occurs a fraction of a second before a person or other
primate initiates a movement. Those neurons do not directly receive sensory
input, nor do they directly stimulate movement of the body. Instead, Svoboda
says, their activity represents a cognitive phenomenon. “You can actually read
out from the neurons what the animal will do in the future,” he says. “In
humans, you can record this activity with an EEG electrode and read out in
coarse terms when and how a person will move, before he or she is aware of
where they will move.”
Still, Svoboda says, there had been no direct evidence that the
brain translated this pre-movement signaling into motor commands. Furthermore,
seemingly conflicting observations about how the left and right side of the
premotor cortex affect movement had left scientists puzzled.
Most of what is known about the premotor cortex comes from
observations of patients and experiments with primates. Patients whose premotor
cortex is damaged during a stroke lose the ability to plan movements on the
side of the body opposite the injured side of the brain. “So when a person has
a lesion on one side, there is a strongly lateralized effect. But the dynamics
of the neurons that people have found in neurophysiology experiments really
don’t jibe with that,” Svoboda says.
Scientists had found about an equal number of cells on both
sides of the premotor cortex whose activity was associated with movement to the
left side of the body; the same was true for neurons associated with movement
to the right side of the body. “It looks like the planning activity is
completely distributed for both sides in both hemispheres,” Svoboda says.
About a year ago, Svoboda’s team identified a region in the
brains of mice that behaves like the premotor cortex in humans and other
primates. That, he says, opened the opportunity for more precise experiments.
To learn more about how neuronal activity during this
preparatory period affect movements, the team used a technology called
optogenetics, in which a light-sensitive protein is genetically introduced into
neurons so that experiments can switch the cells on or off with a laser pulse.
Postdoctoral researchers Nuo Li and Zengcai Guo developed a behavioral task in
which they trained mice to respond to a sensory cue – a pole whose position an
animal could detect with its whiskers – by licking to either the right or the
left, following a delay of 1.3 seconds to allow for movement planning.
Li then silenced neurons on either side of the premotor cortex-like part of the
mouse brain, known as the anterior lateral motor cortex. Optogenetics allows
for millisecond precision, so Li could silence the neurons specifically during
the movement-planning period. Silencing neurons on the right side impaired the
animals’ ability to lick towards the left, whereas silencing neurons on the
left side impaired their ability to lick toward the right. But just as other
scientists had observed in primates and humans, when Li monitored neural
activity in the animals’ anterior lateral motor cortex, about the same number
of neurons on each side fired in advance of movements toward either side of the
body.
Many types of cells wend their way through this part of the
brain and previous experiments were unable to sort out different neurons in the
mix. By applying new optogenetics tools to examine activity in specific cell
types, the team found a small group of neurons whose activity was associated
only with future movements on the opposite side of the animal’s body. These
were pyramidal tract neurons, which extend to the motor centers that produce
movement. Research specialist Tsai-Wen Chen used imaging to follow the activity
of the pyramidal tract neurons, and found the same relationship with movements
on the opposite side of the body.
“In the cortex, we have neurons that project to half a dozen
different brain areas,” Svoboda says. “These output neurons are a small
minority of cells in this region, so if you record indiscriminately from all
neuron types, they get washed out,” Svoboda says. “To understand how the brain
works, we really have to study the neural code at the level of defined neural
populations.”
The scientists found that they could influence the direction of
an animal’s licking response by stimulating the pyramidal tract neurons. “If we
stimulate these neurons during motor preparation, seconds before movement, this
causes the animal to move into the contralateral [opposite side] direction much
more often than it would otherwise,” Svoboda says. “This really shows these
brain areas and these neurons are causally related to planning these
movements.”
“So a very simple picture arises,” Svoboda says. “The motor plan
is distributed across both hemispheres, which talk strongly to each other.
Activity is widely distributed, involving neurons that interact with sensory
areas. Just before movement, this motor plan is effectively downloaded into the
pyramidal tract neurons. And it’s in these neurons that we see strongly
lateralized population activity.”
With a new
understanding of the circuit that connects motor planning to movement,
Svoboda’s team is eager to begin investigating how that planning activity is
generated, how the motor cortex participates in decision making, and how
information about the plan is stored until a movement is executed. “You cannot
write a computer program to generate this based on what we know about neurons,”
he says. “There are real mysteries there.”
Selected and edited
from - http://neurosciencenewsDOTcom/motor-movement-planning-neural-network-1810/
** **
1421
hours. What does this have to say about free will? Obviously the brain comes up
with a solution but only when you have time to be conscious of it can you change
your mind. I think of someone going in to a burning building to rescue someone.
Sometimes, in a quick moment perhaps a person does not know what she or he is
doing – it is just done – for good or bad consequences. I suppose this is what
we have judges and juries for.
What you really wonder is, “Is thinking
really a form of coding?” And, you think, ‘Does big Blue play real chess or is
it all mathematics (probabilities).
Outside
of fewer mistakes what is the real difference between a computer playing chess
and a chess master playing chess? Where and what is the evidence one-way or the
other? It is back to definition. (1432) Sometimes we do not only know the right
questions to ask, we don’t even know the right words to construct these [right]
questions. More and more I side with Socrates – “I [Richard] know little to
nothing and neither does anyone else.”
This fact can be used as an advantage,
orndorff. – Amorella
1437
hours. I am not interested in power, Amorella. Besides, I don’t know that the
above is a fact. How can it be? It is comment. All we can do is construct good
questions and go about answering them the best we can. That’s my opinion. I
need a nap.
Bill and Jen came over late this afternoon
and everyone spent at least a half in the pool. You did ‘bicycle’ exercises
during this time, thus you spent an hour on exercises today. Tonight, you all
went to The Original Pizza for supper. This is up in the 15,500 block of Gulf
Boulevard in Indian Shores Beach area. You brought home the leftovers and sent
today’s lunch leftovers (quite considerable) to Bill, Jen, Jean, and James for
tomorrow’s lunches. The sisters are talking in the living room as they have
been. – Amorella
2152
hours. I am glad they are enjoying themselves. I join the conversations once in
a while, but I don’t have much to say so I mostly listen. They are polite while
I am in the room, but the tempo heightens when I leave. When I first met Linda,
Gayle and Mary Lou, Linda was in the seventh grade, Gayle in the ninth and Mary
Lou was a junior at Fort Hunt High School near Alexandria, Virginia. Carol was
a freshman at Otterbein. That was quite some years ago; 1966. We married 25
November 1967 in Alexandria and have had a good life and marriage. No
complaints. I cannot really imagine my life ever being any different than it has
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