title: Marking multi-channel silicon-substrate electrode recording sites using radiofrequency lesions.
abstract: Silicon-substrate multi-channel electrodes (multiprobes) have proven useful in a variety of electrophysiological tasks. When using multiprobes it is often useful to identify the site of each channel, e.g., when recording single-unit activity from a heterogeneous structure. Lesion marking of electrode sites has been used for many years. Electrolytic, or direct current (DC) lesions, have been used successfully to mark multiprobe sites in rat hippocampus [Townsend G, Peloquin P, Kloosterman F, Hetke JF, Leung LS. Recording and marking with silicon multichannel electrodes. Brain Res Brain Res Protoc 2002;9:122-9]. The present method used radio-frequency (rf) lesions to distinctly mark each of the 16 recording sites of 16-channel linear array multiprobes, in chinchilla inferior colliculus. A commercial radio-frequency lesioner was used as the current source, in conjunction with custom connectors adapted to the multiprobe configuration. In vitro bench testing was used to establish current-voltage-time parameters, as well as to check multiprobe integrity and radio-frequency performance. In in vivo application, visualization of individual-channel multiprobe recording sites was clear in 21 out of 33 sets of collicular serial-sections (i.e., probe tracks) obtained from acute experimental subjects, i.e., maximum post-lesion survival time of 2h. Advantages of the rf method include well-documented methods of in vitro calibration as well as low impact on probe integrity. The rf method of marking individual-channel sites should be useful in a variety of applications.
authors.affiliation: Division of Otolaryngology, Head & Neck Surgery, Southern Illinois University School of Medicine, Springfield, IL 62794, USA. tbrozoski@siumed.edu
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Brozoski
authors.forename: Donald M
authors.initials: DM
authors.lastname: Caspary
authors.forename: Carol A
authors.initials: CA
authors.lastname: Bauer
mesh_terms: D000818:Animals; D002682:Chinchilla; D004558:Electric Stimulation; D004594:Electrophysiology / Q000295:instrumentation* / Q000379:methods*; D007245:Inferior Colliculi / Q000502:physiology*; D008297:Male; D008839:Microelectrodes; D011846:Radio Waves; D012825:Silicon
chemical_list: D012825:Silicon