Tuesday, December 21, 2010

fast kalman filtering draft

hi all, any comments on this draft we just finished would be very welcome.

Wednesday, December 15, 2010

Carl Smith : Dec 15

This Wednesday I'll pick up where we left off last week when we covered graphical models, exponential families, and the basic ideas behind variational inference. This week I will go over variational inference in greater depth, and then describe some approximations to the variational problem that render it tractable: sum-product and the Bethe entropy approximation; mean field methods (time permitting); and convex approximations, in particular tree-reweighted belief propagation. The material is drawn from chapters 3, 4, 5, and 7 of the same paper.

Tuesday, December 7, 2010

Yashar Ahmadian : Dec 8

Designing optimal stimuli to control neuronal spike timing

We develop fast methods for optimal control of spike times by stimulating neurons. We 
adopt an approach based on models which describe how a stimulating agent (such as an 
injected electrical current, or a laser light interacting with caged neurotransmitters or pho- 
tosensitive ion channels) affect the spiking activity of neurons. Based on these models, we 
solve the reverse problem of finding the best time-dependent modulation of the input, sub- 
ject to hardware limitations as well as physiologically inspired safety measures, that makes 
the neuron emit a spike train which with highest probability will be close to a target spike 
train. We adopt fast convex constrained optimization methods to solve this problem. Our 
methods can potentially be implemented in real time and are also generalizable to the case 
of many cells, suitable for neural prosthesis applications. Using biologically sensible param- 
eters and constraints, our method finds stimulation patterns that generate very precise spike 
trains in simulated experiments. We also tested the intracellular current injection method 
on pyramidal cells in mouse cortical slices, achieving sub-milisecond spike timing precision 
and high reliability with constrained currents.

Wednesday, December 1, 2010

cosyne abstracts

hey, our submitted cosyne abstracts are here - any feedback on any of these would be very welcome.