[Neuroscience] Re: Decay constants. What does "weighted' mean?

Trevor Lewis via neur-sci%40net.bio.net (by t.lewis from unsw.edu.au)
Mon Jan 19 21:01:23 EST 2009


Hi Bill,

Why do people do it this way? Let me provide an example that I am 
most familiar with. Take the development of inhibitory synapses in 
the lateral superior olive: they start out predominantly comprised of 
GABA type A receptors and gradually glycine receptors are introduced 
so that there is a mixture of the two at the synapse and then 
eventually become predominantly comprised of glycine receptors. The 
IPSCs from GABAaRs is slow, while GlyRs are fast. In this case it is 
useful to have a weighted mean time constant to describe the 
exponential decay of the IPSCs over the different developmental 
stages - since at some stages there will be two exponential 
components, and other stages just one component. Thus, the change 
from the slow IPSCs to the fast IPSCs can be described with a single 
parameter and can be easily plotted against time. Of course, you 
wouldn't rely solely on this analysis to describe what is happening. 
Certainly, if you were wanting to compare the relative contributions 
of the fast and slow components then a more robust statistical 
comparison would be useful (like a 2-way ANOVA).

Trevor


At 04:04 AM 20/01/2009, you wrote:
>Date: Sat, 17 Jan 2009 20:02:19 -0800 (PST)
>From: Bill <connelly.bill from gmail.com>
>Subject: [Neuroscience] Re: Decay constants. What does "weighted"
>         mean?
>To: neur-sci from net.bio.net
>Message-ID:
>         <9247173e-1e8a-42e5-b05e-cd8d89ccd12a from r10g2000prf.googlegroups.com>
>Content-Type: text/plain; charset=ISO-8859-1
>
>Thanks Trevor, that explains it nicely (I geussed it was something
>like that).
>
>Why do people do it in that way? Wouldn't it make more sense if you
>were comparing an intervention to do a 2-way ANOVA with Intervention
>vs Slow Decay Constant vs Fast Decay Constant?




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