A tailored biocompatible neural interface for long term monitoring in neural networks

Neural interface electrodes that can record from neurons in the brain for long periods of time will be of great importance to unravel how the brain accomplishes its functions. However, current electrodes usually cause significant glia reactions and loss of neurons within the adjacent brain parenchyma. To address this challenge, a novel, polymer-based neural probe, with protrusions tailored to the target tissue, was developed to investigate which probe properties affect the development of a glial scar and neuronal cell death surrounding probes. After many cycles of testing – refinements, promising recordings of neural activity were obtained in both cerebellum
and cortex cerebri (papers I-III). In paper IV, we evaluated the importance of mechanical flexibility and demonstrated that probe flexibility has a significant impact on the astroglial scar, but not on the loss of neurons nearby. Moreover, by embedding the dummy probes in a gelatin matrix that dissolves shortly following implantation, neuronal cell death surrounding chronically (6 weeks) implanted electrodes was, for the first time, abolished. In paper V, sensory processing in primary somatosensory cortex during an episode of hyperalgesia was monitored using implanted neural interfaces in order to further evaluate the probe functionality and usefulness in neurophysiological research. By tracking the development of primary and secondary hyperalgesia as well as allodynia in the sensory cortex, we demonstrate the usefulness of our new neural interface and its capability to differentially and simultaneously record neural signals in different cortical laminae in awake freely moving animals.