I kYES more powerful than NO; wired in brain
http://www.cnsfound ation.org/ site/News2? page=NewsArticle &id=8745& security= 1&news_iv_ctrl= -1
Why we learn more from our successes than our failures
MIT study sheds light on the brain's ability to change in response to
learning
July 29, 2009
Source:
Massachusetts Institute of TechnologyIf you've ever felt doomed to repeat your mistakes, researchers at MIT's
Picower Institute for Learning and Memory may have explained why:
Brain cells may only learn from experience when we do something right and not when we
fail.
In the July 30 issue of the journal Neuron, Earl K. Miller, the Picower
Professor of
Neuroscience, and MIT colleagues Mark Histed and Anitha Pasupathy
have created for the first time a unique snapshot of the learning process
that shows how single cells change their responses in real time as a result of
information about what is the right action and what is the wrong one.
"We have shown that brain cells keep track of whether recent behaviors were
successful or not," Miller said. Furthermore, when a behavior was
successful, cells became more finely tuned to what the animal was learning. After a
failure, there was little or no change in the brain — nor was there any
improvement in behavior.
The study sheds light on the neural mechanisms linking environmental
feedback to
neural plasticity — the brain's ability to change in response to
experience. It has implications for understanding how we learn, and understanding
and treating
learning disorders.
Rewarding success
Monkeys were given the task of looking at two alternating images on a
computer screen. For one picture, the animal was rewarded when it shifted its
gaze to the right; for another picture it was supposed to look left. The
monkeys used trial and error to figure out which images cued which movements.
The researchers found that whether the animals' answers were right or
wrong, signals within certain parts of their brains "resonated" with the
repercussions of their answers for several seconds. The neural activity following a
correct answer and a reward helped the monkeys do better on the trial that
popped up a few seconds later.
"If the monkey just got a correct answer, a signal lingered in its brain
that said, 'You did the right thing.' Right after a correct answer, neurons
processed information more sharply and effectively, and the monkey was more
likely to get the next answer correct as well," Miller said, "But after an
error there was no improvement. In other words, only after successes, not
failures, did brain processing and the monkeys' behavior improve."
Split-second influence
The
prefrontal cortex orchestrates thoughts and actions in accordance with
internal goals while the
basal ganglia are associated with motor control,
cognition and emotions. This work shows that these two brain areas, long
suspected to play key roles in learning and memory, have full information
available to them to do all the neural computations necessary for learning.
The prefrontal cortex and basal ganglia, extensively connected with each
other and with the rest of the brain, are thought to help us learn abstract
associations by generating brief neural signals when a response is correct or
incorrect. But researchers never understood how this transient activity,
which fades in less than a second, influenced actions that occurred later.
In this study, the researchers found activity in many neurons within both
brain regions that reflected the delivery or withholding of a reward lasted
for several seconds, until the next trial. Single neurons in both areas
conveyed strong, sustained outcome information for four to
six seconds, spanning
the entire time frame between trials.
Response selectivity was stronger on a given trial if the previous trial
had been rewarded and weaker if the previous trial was an error. This occurred
whether the animal was just learning the association or was already good at
it.
After a correct response, the
electrical impulses coming from neurons in
each of the brain areas was more robust and conveyed more information. "The
signal-to-noise ratio improved in both brain regions," Miller said. "The
heightened response led to them being more likely to get the next trial correct,
too. This explains on a neural level why we seem to learn more from our
successes than our failures."
now I've been MIA here a lot, but I received this from another list and thought it went along with this question.
