Another and perhaps more important application of the movable probe concept is in so-called chronic recordings, where electrodes are surgically inserted into the brain tissue. The advantage of this method is that the microelectrodes could be placed in the brain area of interest and they can gather large volumes of data in a relatively short time. The major difficulties in chronic recordings include the deterioration of performance over time, very often due to encapsulation of the electrodes by scar tissue as well as inflammatory processes in the brain. Sometimes, the receptive fields of the neurons that are recorded from are non-optimal and not particularly tuned to the variable of interest. Therefore, it might be advantageous to be able to move or reposition the microelectrodes within the implant, break through encapsulation or simply look for a cell with better tuning properties.

Here is a list of people involved in this project:

• Eddie Branchaud
• Joel Burdick
• Zoran Nenadic

I have developed a simulated environment for testing the movable probe algorithm. The following slide summarizes the algorithm:

(please click on the slide for a full size image)



Take a look at some animations of movable probes

1. Stochastic gradient animation (0.5MB, duration: 22 sec)
2. Basis functions animation (0.5MB, duration: 17.5 sec)