[Comp-neuro] Oscillations

jim bower 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. 

Jim
Sent via BlackBerry by AT&T

-----Original Message-----
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)
Harry Erwin




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