In the former, we provide gsk3 alpha examples of the complex stimuli that can be performed with NeuroRighter, and present descriptive results. In the latter, we demonstrate and discuss some of the issues concerning optically induced artifacts. DESIGN DESIGN CRITERIA We designed our optoelectrophysiology system to adapt the in vivo capabilities

of NeuroRighter into the optogenetic purview. In so doing, we wished to maintain the standards established in its original design – that the system be (1) inexpensive, interfacing with commercially available hardware as well as custom-designed solutions; (2) maintain the high spatial and temporal resolution required in electrophysiology; (3) function robustly in a number of different experimental environments; and (4) be open-source. HARDWARE AND SOFTWARE FOR OPTICAL STIMULATION While many of efforts with optogenetics relied on the use of lasers (Yizhar et al., 2011; Armstrong et al., 2013), high-intensity light-emitting diodes (LEDs) have increasingly proven an attractive alternative, particularly for in vivo experiments (Cardin, 2012; Nguyen et al., 2014). Lasers tend

to be large and cumbersome, and many setups require careful collimation and alignment for proper function and maintenance of consistent output within and between experiments. These designs are sensitive to the slight perturbations generated from connections

to awake and behaving animals. Collimated LEDs, however, are compact, robust, and readily portable, making them easy to integrate into behavioral experiments. In addition, LEDs have a more precise input/output relationship than similarly-priced lasers. LED luminance output can be well approximated by a logarithmic or linear function with respect to input current. In contrast, similarly priced DPSS lasers have a non-linear sigmoidal relationship with input voltage (Figure ​Figure1C1C; Cardin, 2012). Furthermore, the light intensity generated by Anacetrapib these lasers can be unstable and demonstrate transient peaks and fluctuations (Cardin, 2012). The output intensity of LEDs, in contrast, is much more stable and better approximates a square wave, with much less variation over time. Indeed, we have determined that the variability in 465 nm Blue LED output intensity is less than that of a comparable-cost laser 475 nm DPSS Laser (Shanghai Dream Lasers, China; Figure ​Figure1C1C). While the standard deviation of the laser intensity output could be over 10% of the maximum output, the standard deviation of the LED intensity output was small enough to be obscured by the datapoint marker. It should be noted that the outputs of lasers and LEDs are influenced by temperature as well.