bower at uthscsa.edu
Wed Jul 23 16:12:53 CEST 2008
Many interestimg ideas in this discussion, which we can probably anticipate will continue in person at the upcoming CNS meeting, which was the initial origin of this mailing list -- so perhaps this is an interesting way to prime the pump for that meeting.
I would caution however about what I have come to think of as "the tyrany of ideas" in computational neuroscience or biology in general. The brain is probably about the most dangerous place you can think of to look for proof of largely a priori ideas.
There are many examples, the Marr/Albus model of cerebellar learning for example has produced almost 50 years of efforts by experimentalists and theorist/modelers to generate evidence it is true.
Much of the work on oscillations is similar, an idea (from machine vision and AI originally related to the imagined problem of segmentation) in search of evidence.
I suppose it is obvious, but my overall point here is that we have to be very very careful about our assumptions given our ignorence.
(And by the way sorry for the spelling and other errors - writing from my blackberry on a beach in Brazil - so many opportunities for errors. - context being everything or nearly everything.
Sent via BlackBerry by AT&T
From: Harry Erwin <harry.erwin at sunderland.ac.uk>
Date: Wed, 23 Jul 2008 11:47:49
To: <comp-neuro at neuroinf.org>
Subject: [Comp-neuro] Oscillations
An issue I've been thinking about recently is the evidence that goal-
oriented plans can be replayed at various speeds and in both forward
and time-reversed directions. In goal-directed behaviour of bats, the
animal first plans ahead to the target capture (or perhaps retrieves
an appropriate plan from memory). Then later during the capture
process, if the target turns out to be inedible, the bat will sheer
off as late as 30 msec prior to contact. I guestimate that the
original capture plan was generated or retrieved in about 5% of the
time necessary to execute it, and the back propagation through time of
revised reward estimates takes place in about the same time. I suspect
the plan is represented as a set of discrete intermediate subgoals,
and that there is an oscillatory process that steps through the
subgoals to replay the plan. Chip Levy's evidence about sharp waves
during sleep suggests some mechanisms that would allow the speed and
direction of the process to be varied.
"an academic who listens to pleas of convenience before publishing his
research risks calling into doubt the whole of his determination to
find the truth." (Russell 1993)
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