Neuroelectronic interfacing with cultured multielectrode arrays toward a cultured probe

Abstract

Efficient and selective electrical stimulation and recording of neural activity in peripheral, spinal, or central pathways requires multielectrode arrays at micrometer scale. At present, wire arrays in brain, flexible linear arrays in the cochlea and cuff arrays around nerve trunks are in experimental and/or clinical use. Twoand three-dimensional brush-like arrays and sieve arrays, with around 100 electrode sites, have been proposed, fabricated in microtechnology, and/or tested in a number of labs. As there are no "blueprints" for the exact positions of neurons, an insertable multielectrode has to be designed in a redundant way. Even then, the efficiency of a multielectrode will be less than 100%, as not every electrode will contact a neural axon or soma. Therefore, "cultured probe" devices are being developed, i.e., cell-cultured planar multielectrode arrays (MEAs). They may enhance efficiency and selectivity because neural cells have been grown over and around each electrode site as electrode-specific local networks. If, after implantation, collateral sprouts branch from a motor fiber (ventral horn area) and if they can be guided and contacted to each "host" network, a very selective and efficient interface will result. Four basic aspects of the design and development of a cultured probe, coated with rat cortical or dorsal root ganglion neurons, are described. First, the importance of optimization of the cell-electrode contact is presented. It turns out that impedance spectroscopy, and detailed modeling of the electrode-cell interface, is a very helpful technique, which shows whether a cell is covering an electrode and how strong the sealing is. Second, the dielectrophoretic trapping method directs cells efficiently to desired spots on the substrate, and cells remain viable after the treatment. The number of cells trapped is dependent on the electric field parameters and the occurrence of

Biology on a Chip: Microfabrication for Studying the Behavior of Cultured Cells

“…To better define the cell-to-electrode distance, electrodes have been coated with ECM proteins, 177 poly lysine, 178,179 or silane-based monolayers. 180 In addition, electroplating of Pt-back 181 or coating metal electrode with electrically conductive polymers (e.g., polypyrrole) 182 can be used to lower the impedance of the electrode sites. Cell positioning onto electrodes can be improved by surface micropatterning to improve the sensitivity and repeatability of MEA recordings.…”

Development of a Neural Interface for PNS Motor Control

“…The range of resistances is larger in the latter case, indicating that the relative positions of the electrode and cell body play an important role in determining R seal regardless of whether the electrode is completely covered. High quality cell-electrode contacts, where quality is determined by electrode coverage and sealing, will permit selective and reliable recording [33]. Experiments have similarly demonstrated that the sealing resistance increases when the electrode is completely covered by the cell and drops off sharply when any portion is exposed directly to the medium [31].…”

“…Because of the massive amounts of information exchanged between end organs and the brain during seemingly common tasks, future rehabilitative applications, like graded neuromuscular control or for prosthetic vision, will depend on the availability of large-scale, selective neural interfaces [33]. This requires that the neural interface record efferent nervous signaling with enough specificity to reproduce fine motor control [12].…”

“…Furthermore, at least two groups are currently working to address the problem of enhancing such blind-ended axonal regeneration and stabilizing its long-term survival and viability by incorporating biological elements into the endcap, such as growth factors, as are frequently used within the context of artificial nerve conduits [69] [68], pools of living exogenous neurons [66], and even muscle cells [70][71][72]. Finally, in vitro designs have also been proposed, such as the "cultured probe" approach [21,22,33]. Cultured probes are a specific type of MEA in which electrogenic cells, typically neurons, are cultured on top of electrode arrays to promote the formation of an in vitro functional biointerface.…”

Detecting correlation changes in electrophysiological data

“…The neural activities induced by a stimulus, such as an odor, an image or a sound, are routinely recorded by multi-electrode arrays (MEA, see Victor, 1994;Gross, 1995;Rutten et al, 2001;. Usually hundreds or even thousands of local field potentials and neuronal activities are simultaneously recorded at a sample frequency between 1000 Hz and 2000 Hz (Mehring et al, 2003;Todd, 2005).…”