Purkinje cells were loaded with Oregon Green BAPTA-2 and Alexa 633 by adding these dyes to the pipette solution. The experiments
were initiated after the dendrite was adequately loaded with the dyes and the fluorescence at the selected ROIs reached a steady-state level, which typically required ≥ 30min. The recordings were performed at room temperature. Resting calcium levels were calculated as [Ca2+]=KD(G/R)−(G/R)min(G/R)max−(G/R)where KD is the dissociation constant of Oregon Green BAPTA-2, and (G/R)max and (G/R)min are the fluorescence ratios at saturating and zero (external) calcium concentrations, respectively. For this calculation, we used the following values: KD = 485 nM (cuvette measurements), G/Rmax = 0.9440 (in situ measurement; injection of depolarizing currents in [Ca2+]o = 4mM), and G/Rmin = 0.0196 (in situ; no stimulation; [Ca2+]o = 0 mM). Selleck Y 27632 Data were analyzed using Fitmaster software (HEKA Electronics) and Igor Pro software (WaveMetrics). Linearity was assessed by
using Pearson’s correlation coefficient, and statistical significance was Ribociclib mw determined by using the paired Student’s t test (to test for significance of changes after an experimental manipulation in comparison to baseline) and the Mann-Whitney U test (between-group comparison), when appropriate. All data are shown as mean ± SEM. This study was supported by grants from the National Institute of Neurological Disorders and Stroke (NS-062771 to C.H. and NS-038880 to J.P.A.), the Netherlands Organization for Scientific Research (NWO-ALW 817.02.013 to C.H.), and the Japanese Society for the Promotion of Science (JSPS 02714 to G.O.). We would like to thank S.M. Sherman, N. Spruston, and J. Waters for invaluable comments on the manuscript and
laboratory members for helpful discussions. “
“Neural responses in primary sensory cortices encode the physical attributes of a stimulus with considerable precision. Additionally, these neural responses can reflect a large number of experience-dependent contextual attributes of a stimulus (Meyer et al., 2010, Shuler and Bear, 2006 and Zhou et al., 2010) including those that reflect its 4-Aminobutyrate aminotransferase behavioral significance (Polley et al., 2006, Recanzone et al., 1993, Rosselet et al., 2011, Siucinska and Kossut, 1996 and Weinberger, 2004). On the local network level, neuronal responses to a stimulus are both redundant and sparse (Houweling and Brecht, 2008, Kerr et al., 2007, O’Connor et al., 2010 and Olshausen and Field, 2004). Redundancy, in which the total number of spikes elicited by a sensory stimulus exceeds the number needed for sensory perception (Houweling and Brecht, 2008, Huber et al., 2008 and O’Connor et al., 2010), permits fault-tolerant coding in cortical networks, which have characteristically high response variability. However, redundant coding increases the metabolic load on the system.