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.

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