The differences

between our findings and typical PARP inhibition in vivo responses indicate the importance of components other than native brain cells in the progression of the reactive tissue response. Our findings additionally point to a viable alternative hypothesis regarding neuronal density depletion following microelectrode implantation in the brain. Conflict of interest statement The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Acknowledgments Funding for this research was provided by the Purdue Research Foundation, the Indiana Spinal Cord and Brain Injury Research Grant Program (Fund # 00015115), and the Defense Advanced Research Projects Agency (DARPA) Microsystems Technology Office (MTO), under the auspices of Dr. Jack W. Judy ([email protected]) and Dr. Doug Weber ([email protected]) as part of the Reliable Neural Technology Program, through the Space and Naval Warfare Systems Command (SPAWAR) Systems Center (SSC) Pacific grant No. N66001-11-1-4013. Thanks to members of the Neuroprostheses Research Laboratory for feedback on the manuscript.
Optogenetic techniques provide powerful tools for precise manipulation of complex nervous system circuitry. Selective

excitation and inhibition with light of a genetically targeted neuron population – without directly perturbing the neighboring untargeted cells – has provided the means to elegantly explore a number of important neuroscience questions (Aravanis et al., 2007; Carter et al., 2009; Gradinaru et al., 2009; Kravitz et al., 2010; Yizhar et al., 2011; Packer et al., 2012; Wykes et al., 2012; Paz et al., 2013). When combined with electrophysiological recording techniques, optogenetic control can provide unprecedented insight into neural connectivity and function (Bell et al., 2013), as well as suggest potential therapeutic

strategies (Gradinaru et al., 2009; Paz et al., 2012; Wykes et al., 2012; Krook-Magnuson et al., 2013). Optogenetics combines a number of techniques in molecular biology, electrophysiology, optics, and neuroscience, the mastery of which can prove a barrier to easy adoption. Significant efforts have been made to expand the toolbox of optogenetic channels, constructs, and viral techniques (Chow et al., 2010; Gunaydin et al., 2010; Diester Dacomitinib et al., 2011), as well as to develop complex custom-designed optoelectric neural interfaces (Fan et al., 2013; Voigts et al., 2013). However, commercial electrophysiology hardware and software has lagged behind these developments, and often fails to incorporate support for complex stimuli, real-time multielectrode closed-loop control (Newman et al., 2013), and customized experimental configurations in awake and behaving animals. In addition, the cost of these systems is often prohibitive, particularly for investigators looking to initiate a
of research with limited funding.