Once polished, the free end of the fiber was scored and cleaved to 10–12 mm in length. Custom hardware and software was designed

in order to standardize AEB071 solubility the variations in output intensity and calibrate each ferrule2. An intensity calibration device (ICD; Figure ​Figure1F1F, bottom) was designed in Solidworks 2011 (Dassault Systèms Solidworks), 3D-printed on an Objet Eden 250 from FullCure 720 model resin, and painted black. A S121C silicone diode (Thorlabs) was placed within the central cavity of the ICD and connected to a PM100USB intensity meter (Figure ​Figure1F1F, top). Custom-written LabVIEW 2009 software (National Instruments, Austin, TX, USA; Figure ​Figure1G1G) steps the LED through user-defined output voltages and measures the resultant power for a defined wavelength and number of points on the S121C silicone diode. LED output power passing through the ferrule is thus correlated to the analog input voltage signal to the LED controller. The program then calculated intensity from power based on the diameter of the

fiber optic and linearly correlated to the voltage input. This standardized the output of each ferrule based on intensity rather than voltage input, enabling precise stimulation at accurate intensities across all experimental subjects. Custom-written Matlab scripts then converted standard output intensities to the appropriate signal voltages for each test subject. Ferrules were attached to the patch fiber cable by means of 1.25 mm inner diameter ceramic split sleeves (Precision Fiber Products). These were reinforced by threading them through trimmed heat shrink tubing (Digi-Key, Thief River Falls, MN, USA), and subsequently heating them. These reinforced sleeves were superior to the bare split-sleeves in resisting breakage due to vigorous movement of some subjects. This ceramic split sleeve was the most common breaking point in the connection, conveniently leaving the implanted ferrule and patch fiber cables intact. ELECTRODE ARRAYS Two electrode array configurations

Carfilzomib were used in these proof-of-concept experiments. For recording of the dorsal hippocampus while simultaneously stimulating the MS, 16-channel microwire multielectrode arrays [Tucker Davis Technologies (TDT), Alachua, FL., USA; MEA] were constructed from sixteen 33 μm diameter tungsten electrodes with polyimide insulation (Figure ​Figure1I1I). The electrodes were arranged in two rows of eight electrodes with 1 mm between rows and 175 μm of space between the electrodes within a row. Ground and reference wires were separated on the array and routed through two stainless steel wires, which were affixed to separate skull screws during the implantation surgery. The two rows were cut to different lengths, 4.0 and 3.