Hypoxia, Leptin and Hippocampal Neurons Firing Figure 6. Hypoxia increases the synchronization of the spontaneous activity. A. Raster plots showing the activity from different channels of a MEA at 11 (left) and 18 DIV (right) in control condition and after the hypoxic treatment (bottom). B. Cross-correlogram plots showing the enhancement of cross-correlation after hypoxia (grey traces) vs control conditions (black traces), at 11DIV (left) and 18 DIV (right). Probability of coincidence detection increased by 600% and by 76%, respectively. In both cases, firing frequency is drastically reduced. doi:10.1371/journal.pone.0041530.g006 PLoS ONE | www.plosone.org 9 July 2012 | Volume 7 | Issue 7 | e41530