A: typical traces recorded in gap-free mode at −70 mV membrane holding potential [Vhold (Vh)] in standard artificial cerebrospinal fluid (ACSF). EPSC, excitatory postsynaptic current. Traces were obtained from WT, CAG160, and CAG310 R6/2 mice at 80 days. B: bar graphs show mean (±SE) spontaneous EPSC frequency recorded in standard ACSF for each group at the ages indicated. C: bar graphs show mean (±SE) spontaneous EPSC frequency recorded in standard ACSF with 20 μM bicuculline methobromide (BIC) for each group at the ages indicated. At 21 days, in both B and C, data were obtained only from the CAG160 line and their WTs. *P < 0.05, ***P < 0.001 with respect to WT; †P < 0.05, ††P < 0.01, †††P < 0.001 with respect to CAG160; ‡P < 0.05 with respect to CAG310.