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. Author manuscript; available in PMC: 2017 Aug 1.
Published in final edited form as: J Biol Rhythms. 2016 Dec 20;32(1):35–47. doi: 10.1177/0748730416680904

Figure 1. SCN cells resynchronize as two groups.

Figure 1

Representative data from SCN cells in a slice show the loss and restoration of coordinated daily rhythms in PER2 expression during and after treatment with tetrodotoxin (0.3 μM TTX) for 6 days (grey background). A) Upon removal of TTX, the Synchronization Index returned to a value close to 0.9 indicating that cells were oscillating roughly in phase with the same circadian period. (Note that the computation requires each experimental condition to be evaluated separately, and that the phase cannot be estimated accurately during the first or last 1.5 cycles, leaving gaps of time during which we cannot assess the degree of synchrony.) B) PER2 expression from representative regions of the SCN (each colored trace comes from every 100’th 4×4 pixel group). K-means (k=2) clustering analyses of the traces revealed similar spatial organization of these SCN cells before and after TTX treatment based on their average peak time (C. red cells had a later peak time than blue cells) or their mean amplitudes (D, magenta cells had higher amplitude than cyan cells).