A Control System for Positioning Recording Electrodes to Isolate Neurons in Extracellular Recordings

Citation

Branchaud, Edward Allan (2006) A Control System for Positioning Recording Electrodes to Isolate Neurons in Extracellular Recordings. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/6HHC-5456. https://resolver.caltech.edu/CaltechETD:etd-06042006-160620

Abstract

This thesis presents an algorithm that autonomously positions recording electrodes inside cortical tissue so as to isolate and then maintain optimal extracellular signal recording quality without human intervention. The algorithm is used to improve the quality and efficiency of acute (daily insertion) recordings that are needed for basic research in neurophysiology. It also offers the potential to increase the longevity and quality of chronic (long-term implant) recordings by controlling an emerging class of chronic arrays in which the electrodes can be continually repositioned after implantation.

The challenges encountered in attempting to isolate neurons are studied. A solution is proposed in which a finite state machine oversees a number of signal processing steps, computes various metrics of the recording quality and issues commands to move the electrode close to neurons without causing them damage. A number of metrics of the quality of neuron isolation are compared.

The algorithm has been used to control a number of commercial microdrive systems, including a single-electrode FHC microdrive and multielectrode microdrives from Thomas Recording and NAN, as well as a novel miniature microdrive. The autonomous positioning software is used by several neuroscientists to perform basic neurophysiology research. Analysis of the system's performance in isolating neurons is included.

Thesis Files