Before revision:  By varying p_c from p_c^*, we find that a plot of saturated learning gain degree {\cal L}_g^* versus p_c forms a bell-shaped curve with a peak at p_c^* (where the diversity degree in firing of GR cells is also maximum).
After revision:  By varying p_c from p_c^*, we find that a plot of saturated learning gain degree {\cal L}_g^* versus p_c forms a bell-shaped curve with a peak at p_c^* (where the diversity degree in spiking patterns of GR cells is also maximum).