[Comp-neuro] Query: Calcium Spike

James Schwaber schwaber at mail.dbi.tju.edu
Sat Aug 30 15:28:06 CEST 2008


>     Hi Harry - My colleagues and collaborators Raj Vadigepalli and
>     Ilya Rybak I believe have possibly relevant experience in modeling
>     persistent calcium and I forwarded this to them - I hope you hear
>     from one or both. - Jim :

Harry,

I believe Ilya's ramp-firing respiratory neuron model (referred to as 
'type II' in Rybak et al., JNeurophysiol 1997; PubMed 9114250) with 
Ca_T, K_AHP(Ca) and Ca2+ buffer in a 'thin shell' near the membrane, 
exhibits this kind of behavior. Figure 6 in the attached paper shows 
that the Calcium 'spike' lasts over 100-200 ms... not sure if that is 
long enough in your system.

Regards,
Raj

-----
Rajanikanth Vadigepalli
Research Assistant Professor
Daniel Baugh Institute for Functional Genomics
  and Computational Biology
Department of Pathology, Anatomy and Cell Biology
Room 381, 1020 Locust Street, Thomas Jefferson University
Philadelphia PA 19107
Phone: 1-215-955-0576
Fax: 1-215-503-2636
Email: raj at mail.dbi.tju.edu
WWW: http:/www.dbi.tju.edu/~raj

Harry Erwin wrote:
> Just a query. I'm currently working on a model of an inferior 
> colliculus rebound regular cell. These neurones contain calcium T 
> (Cav3) channels and respond to the end of a period of 
> hyperpolarisation with a 'hump' (a broad multi-msec calcium spike). In 
> bats, sodium spikes can ride on this hump and are believed to indicate 
> that the system has detected an echo after the end of an interval of 
> GABAergic input. Thalamocortical relay and thalamic nucleus 
> reticularis neurones seem to operate in very much the same fashion. 
> Now for the $64,000 question--has anyone managed to model this calcium 
> hump? I'm using the time constants from Huguenard and Prince (1992) 
> and the small calcium spike I'm getting is much too short in duration 
> and in magnitude. The somatic conductances I'm using (in nS/(sq 
> micron)) are Nav1.2, 300; Kv1.4, (4AP-sensitive) 300; Kv1.4, 
> (4AP-resistant) 100; and Cav3, 300. I'm aware that these conductance 
> densities are probably too low, but I would expect the ratios to be 
> more important than the absolute numbers.
>
> -- 
> Harry Erwin, PhD, Senior Lecturer of Computing, University of 
> Sunderland. Computational neuroethologist:
> http://scat-he-g4.sunderland.ac.uk/~harryerw/phpwiki/index.php/AuditoryResearch 
>
>
>
>
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>>
>> -- 
>> "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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