Animal experiments were conducted following protocols approved by Administrative Panel on Laboratory Animal Care at Stanford University. Mice were anesthetized

with tribromoethanol and perfused with 10 ml of PBS, followed by 50 ml of fixative (4% paraformaldehyde diluted in PBS). The brains were removed and postfixed for 3 hr at room temperature and then immersed in 30% sucrose solution overnight before being sectioned at GABA agonists list 30 μm thickness on a cryostat. The free-floating brain sections were collected in PBS and counterstained with DAPI. The brain sections were mounted onto glass slides with Vectashield mounting medium (Vector Laboratories). Micoscopic photos were taken with a Leica DM IRE2 microscope. Photos taken with 10× objective were tiled to generate the image of the whole brain sections. Cultured neurons

were homogenized in lysis buffer (1% SDS, 10 mM Tris), mixed with 6× loading buffer (0.5 M tris, 60% glycerol, 10% SDS, 10% Beta-Mercaptoethanol, and 0.01% bromphenol blue), and denatured at 100°C for 20 min. After centrifugation at 14,000 rpm for 30 min, the supernatants were loaded for SDS-PAGE and immunoblotted with standard chemiluminescence protocols. The primary antibodies used in the study include: anti-syt1 (CL41.1), anti-syb2 (CL69.1), and Synx1 (U6251). Blots were digitized and quantified with National Institutes of Health image software. All band intensities were normalized

to that of control samples. MEK inhibitor We thank Dr. Mark Kay (Stanford University) and Dr. Eric J. Nestler (Mount Sinai Medical School) for AAV vectors and AAV preparation to protocols. This work was supported by NIMH Conte Center project number 5 P50 MH086403-03. “
“The range of natural signals exceeds the dynamic range of neurons. As a result, neural circuits adapt so as to more efficiently encode the recent history of inputs. One widespread example of this process occurs in response to a change in the magnitude of fluctuations, or the variance of a sensory input (Laughlin, 1989). Variance adaptation occurs in many sensory systems, including the vertebrate retina and visual cortex, the fly visual system, and the avian auditory forebrain (Fairhall et al., 2001, Nagel and Doupe, 2006, Ohzawa et al., 1985, Shapley and Victor, 1978 and Smirnakis et al., 1997). When the stimulus environment changes from a low to high variance, temporal filtering quickly accelerates, sensitivity decreases, and the average response increases. (Baccus and Meister, 2002, Chander and Chichilnisky, 2001 and Kim and Rieke, 2001). When the environment maintains a high variance, slow changes occur over 1–10 s, comprised mostly of a homeostatic decay in the average response that opposes the fast change in baseline. (Baccus and Meister, 2002, Fairhall et al., 2001 and Nagel and Doupe, 2006). Upon a decrease in contrast, all these changes reverse direction.