SUO: Re: Definition of Life - FW: [semiosis] cheerleader neurons - telos
"The fundamental point I was trying to illustrate is the fact that
every definition of life involves some notion of goal, purpose, or
"telos". I certainly agree that there are multiple senses of purpose
in the life of the amoeba (and of any other kind of life as well).
But that simply reinforces my argument: every definition of life
requires at least one kind of purpose. If you want to multiply
the kinds, be my guest. You are strengthening my point."
Of interest perhaps.... (and gets into A/~A oscillations etc)....
Scientific American 5/31/02
Research Reveals Brain Signal That Roots for Reward
Encouraging words from a cheerleader can convince someone to keep at an
arduous task in order to reap benefits once the chore is completed. Now the
results of a study published today in the journal Science suggest that a
part of the brain might work in a similar way. According to the report,
scientists have discovered a brain signal in monkeys that increases as an
expected reward nears. The findings could help unravel how the compulsion
characteristic of addiction takes shape in the brain.
Munetaka Shidara of the National Institute of Advanced Industrial Science
and Technology in Japan and Barry J. Richmond of the National Institute of
Mental Health monitored monkeys while the animals performed a series of
tasks in order to receive a reward. The animals learned to release a lever
when a spot on a computer screen turned from red to green. After a number
of successful attempts, they received their prize. In some of the trials, a
bar on the screen tracked their progress and got brighter as the animals
approached the reward. As the monkeys performed the tasks, the scientists
investigated the activity of more than 100 neurons located in the anterior
cingulate cortex, a region of the brain involved in performance and
conflict monitoring, error detection, and response selection.
The activity of about one third of the brain cells, the team found, varied
with the level of expectation of a reward--the closer the reward seemed,
the more they fired. The animals also made the fewest errors in the task
just prior to receiving their reward. When the possibility of receiving a
reward was randomized, however, these neurons did not display increasing
activity. Of particular note is the fact that the signal actually died down
just before the prize was reached. "Understanding the reward is a 'sure
thing' may be more important than actually receiving it," Richmond says.
This cheerleading brain signal could form a biological basis for
goal-driven behavior. "Understanding how this signal works normally, as
well as when its activity is abnormally high or low, may shed light on why
individuals seem to have different levels of motivation for performing
similar tasks," Shidara notes. Moreover, the researchers propose that
misfiring of this reward expectancy circuit could be involved in some
pathological behaviors. "Let's assume you had a signal like this, and it
was turned up too high," Richmond explains. "It might make you feel like
you had to be trying harder, telling you, 'Just go a little further and
you'll get satisfied.' Our speculation is that this signal never resolves
for conditions like [obsessive-compulsive disorder]." --Sarah Graham