Micromanufactured electrodes for cortical field potential recording: in vivo study

Introduction: Electrodes able to perform high-resolution recordings with low interference and long term stable recording of cortical field potentials (CFP) have a wide medical applicability. The utilization of CFP was proposed as control signal for neuronal motor prostheses and epileptology. This study investigates the applicability of micromanufactured electrodes for subdural cortical recordings. Objective: To evaluate the applicability of subdural microelectrodes and study their signal quality across time. Method: A prototype of a grid array with eight platinum microelectrodes (320 µm diameter, arranged as a 2×4 grid with a pitch of 0.95mm) was developed based on laser- structuring of silicone rubber and precious metal foils. The electrodes were connected to a percutaneous plug which was encapsulated in silicone rubber. For the experiment eight adult Wistar rats underwent implantation. The animals were submitted to right parietal craniotomy. After the durotomy the grid was placed above the cortical surface guided by stereotaxic coordinates (aimed at the visual cortical area) and transoperative electrocorticography (ECoG) to ensure optimal contact. The bone flap was reinserted and the system was fixed to the skull with acrylic cement. After the recovering period the rats were taken to systematic bioimpedance measurements and ECoG recordings and the signal was analyzed with Spike2 and Matlab7.3. Results: The rats presented normal behavior during the recording sessions. The mean amplitude values were stable over a four weeks period. The impedances increased one week after implantation, but were then stable over a four week period. Conclusion: The use of micromanufactured electrodes may constitute a promising technique for chronic electrocorticographic recordings.

[1]  H. Jasper,et al.  Epilepsy and the functional anatomy of the human brain , 1985 .

[2]  R. Fisher,et al.  Resection of the epileptogenic area in critical cortex with the aid of a subdural electrode grid. , 1990, Stereotactic and Functional Neurosurgery.

[3]  Hisae Gemba,et al.  Cortical field potentials associated with audio-initiated vocalization in monkeys , 1999, Neuroscience Letters.

[4]  Thomas Stieglitz,et al.  Morphologic and functional evaluation of peripheral nerve fibers regenerated through polyimide sieve electrodes over long-term implantation. , 2002, Journal of biomedical materials research.

[5]  T.C. Marzullo,et al.  Spikes, Local Field Potentials, and Electrocorticogram Characterization during Motor Learning in Rats for Brain Machine Interface Tasks , 2005, 2005 IEEE Engineering in Medicine and Biology 27th Annual Conference.

[6]  C. Mehring,et al.  Comparing information about arm movement direction in single channels of local and epicortical field potentials from monkey and human motor cortex , 2004, Journal of Physiology-Paris.

[7]  Andrew B Schwartz,et al.  Cortical neural prosthetics. , 2004, Annual review of neuroscience.

[8]  Hiroshi Shibasaki,et al.  Human eye fields in the frontal lobe as studied by epicortical recording of movement-related cortical potentials. , 2004, Brain : a journal of neurology.

[9]  G. Paxinos,et al.  The Rat Brain in Stereotaxic Coordinates , 1983 .

[10]  Justin C. Williams,et al.  Chronic neural recording using silicon-substrate microelectrode arrays implanted in cerebral cortex , 2004, IEEE Transactions on Biomedical Engineering.

[11]  B Diehl,et al.  Temporal Lobe Epilepsy: When Are Invasive Recordings Needed? , 2000, Epilepsia.