title: Precaution for volume conduction in rodent cortical electroencephalography using high-density polyimide-based microelectrode arrays on the skull.
abstract: In humans, significant progress has been made to link spatial changes in electroencephalographic (EEG) spectral density, connectivity strength, and phase-amplitude modulation to neurological, physiological, and psychological correlates. In contrast, standard rodent EEG techniques employ only few electrodes, which results in poor spatial resolution. Recently, a technique was developed to overcome this limitation in mice. This technique was based on a polyimide-based microelectrode (PBM) array applied on the mouse skull, maintaining a significant number of electrodes with consistent contact, electrode impedance, and mechanical stability. The present study built on this technique by extending it to rats. Therefore, a similar PBM array, but adapted to rats, was designed and fabricated. In addition, this array was connected to a wireless EEG headstage, allowing recording in untethered, freely moving rats. The advantage of a high-density array relies on the assumption that the signal recorded from the different electrodes is generated from distinct sources, i.e., not volume-conducted. Therefore, the utility and validity of the array were evaluated by determining the level of synchrony between channels due to true synchrony or volume conduction during basal vigilance states and following a subanesthetic dose of ketamine. Although the PBM array allowed recording with high signal quality, under both drug and drug-free conditions, high synchronization existed due to volume conduction between the electrodes even in the higher spectral frequency range. Discrimination existed only between frontally and centrally/distally grouped electrode pairs. Therefore, caution should be used in interpreting spatial data obtained from high-density PBM arrays in rodents.
authors: AstraZeneca Research and Development, Innovative Medicines and Early Development, Personalized Healthcare and Biomarkers, AstraZeneca Translational Science Centre at Science for Life Laboratory, Solna, Sweden; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; and pjstienen@gmail.com.
authors: P J
authors: PJ
authors: Stienen
authors: AstraZeneca Research and Development, Innovative Medicines and Early Development, Personalized Healthcare and Biomarkers, AstraZeneca Translational Science Centre at Science for Life Laboratory, Solna, Sweden; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; and.
authors: M
authors: M
authors: Venzi
authors: Department of Medical Engineering and Neuroprosthetics, Fraunhofer Institute for Biomedical Engineering, St. Ingbert, Germany.
authors: W
authors: W
authors: Poppendieck
authors: Department of Medical Engineering and Neuroprosthetics, Fraunhofer Institute for Biomedical Engineering, St. Ingbert, Germany.
authors: K P
authors: KP
authors: Hoffmann
authors: AstraZeneca Research and Development, Innovative Medicines and Early Development, Personalized Healthcare and Biomarkers, AstraZeneca Translational Science Centre at Science for Life Laboratory, Solna, Sweden; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; and.
authors: E
authors: E
authors: Åberg
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008839:Microelectrodes / Q000009:adverse effects; D009431:Neural Conduction; D051381:Rats; D012117:Resins, Synthetic
chemical_list: D012117:Resins, Synthetic; C029945:polyimide resin
keywords: gamma; high-density EEG; ketamine; theta