Abstract
Neural interfaces which allow long-term recordings in deep brain structures in awake freely moving animals have the potential of becoming highly valuable tools in neuroscience. However, the recording quality usually deteriorates over time, probably at least partly due to tissue reactions caused by injuries during implantation, and subsequently micro-forces due to a lack of mechanical compliance between the tissue and neural interface. To address this challenge, we developed a gelatin embedded neural interface comprising highly flexible electrodes and evaluated its long term recording properties. Bundles of ultrathin parylene C coated platinum electrodes (N = 29) were embedded in a hard gelatin based matrix shaped like a needle, and coated with Kollicoat™ to retard dissolution of gelatin during the implantation. The implantation parameters were established in an in vitro model of the brain (0.5% agarose). Following a craniotomy in the anesthetized rat, the gelatin embedded electrodes were stereotactically inserted to a pre-target position, and after gelatin dissolution the electrodes were further advanced and spread out in the area of the subthalamic nucleus (STN). The performance of the implanted electrodes was evaluated under anesthesia, during 8 weeks. Apart from an increase in the median-noise level during the first 4 weeks, the electrode impedance and signal-to-noise ratio of single-units remained stable throughout the experiment. Histological postmortem analysis confirmed implantation in the area of STN in most animals. In conclusion, by combining novel biocompatible implantation techniques and ultra-flexible electrodes, long-term neuronal recordings from deep brain structures with no significant deterioration of electrode function were achieved.
Highlights
Neural interfaces have the potential to provide key scientific tools to elucidate how the conscious brain functions at the cellular and network levels and to provide effective therapy for treatment of patients with neurodegenerative or psychiatric conditions [1,2,3]
To avoid using very rapid insertion velocities, which can cause damage to the tissue, we needed to significantly increase the time for dissolution of the gelatin vehicle
To solve this problem the embedded microelectrodes were coated with a double layer of KollicoatTM
Summary
Neural interfaces have the potential to provide key scientific tools to elucidate how the conscious brain functions at the cellular and network levels and to provide effective therapy for treatment of patients with neurodegenerative or psychiatric conditions [1,2,3]. The ability of current neural interfaces to record neuronal activity often deteriorates over time, PLOS ONE | DOI:10.1371/journal.pone.0155109. Embedded Electrodes for Deep Brain Recordings and analysis, decision to publish, or preparation of the manuscript The ability of current neural interfaces to record neuronal activity often deteriorates over time, PLOS ONE | DOI:10.1371/journal.pone.0155109 May 9, 2016
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