preprint available

[Klaus Obermayer]

Dear Connectionists,

attached please find abstract and preprint location of one manuscript on
the analysis of Ca-imaging data from the olfactory system (antennal lobe)
of the honeybee.

Comments are welcome!

Cheers

Klaus

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Prof. Dr. Klaus Obermayer         phone:  49-30-314-73442
FR2-1, NI, Informatik                     49-30-314-73120
Technische Universitaet Berlin    fax:    49-30-314-73121
Franklinstrasse 28/29             e-mail: oby at cs.tu-berlin.de
10587 Berlin, Germany             http://ni.cs.tu-berlin.de/

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Analysis of calcium imaging signals from the honeybee brain by nonlinear models

M. Stetter^1,3, H. Greve^1, C. Galizia^2, and K. Obermayer^1

^1 Fachbereich Informatik, Technische Universitaet Berlin
^2 Institut fuer Neurobiology, Freie Universitaet Berlin
^3 Zentrale Forschung, Siemens AG, Muenchen

Recent Ca$^{2+}$-imaging studies on the antennal lobe of the honeybee 
{\it (Apis mellifera)} have shown that olfactory stimuli evoke complex
spatiotemporal changes of the intracellular Ca$^{2+}$ concentration, in which
stimulus-dependent subsets of glomeruli are highlighted. In this work we use
nonlinear models for the quantitative identification of the spatial and
temporal properties of the Ca$^{2+}$-dependent fluorescence signal. This
technique describes time-series of the Ca$^{2+}$ signal as a superposition of
biophysically motivated model functions for photobleaching and
Ca$^{2+}$-dynamics, provides optimal estimates of their amplitudes (signal
strengths) and time-constants together with error measures. Using this method,
we can reliably identify two different stimulus-dependent signal components.
Their delays and rise times, $delta_{c1} = (0.4 \pm 0.3)$~s, $\tau_{c1} =
(3.8 \pm 1.2)$~s for the fast component and $\delta_{c2} = (2.4 \pm 0.6)$~s,
$\tau_{c2} = (10.3 \pm 3.2)$~s for the slow component, are constant over space
and across different odors and animals. In chronical experiments, the amplitude
of the fast (slow) component often decreases (increases) with time. The pattern
of the Ca$^{2+}$-dynamics in space and time can be reliably described as a
superposition of only two spatiotemporally separable patterns based on the fast
and slow components. However, the distributions of both components over space
turn out to differ from each other, and more work has to be done in order to
specify their relationship with neuronal activity.


in: NeuroImage, in press

available at: http://ni.cs.tu-berlin.de/publications/