Fig. 2.

Restriction and control experiments shown by first (open bars) and second (filled bars) trials. Second trials for restriction experiments showed increased signal compared with first trials of restriction. Second trials for controls showed decreased signal compared to first trial controls. The effect of trial number was significant (mixed model F=14.841, P=0.001). Note that an apparent decrease in the serotonin signal may not represent an actual decrease in serotonin, but may be due to fiber electrodes becoming less sensitive over time, an effect often referred to as electrode fouling (Singh et al., 2011). Bars represent s.e.m.