Figure 2. (A) Current responses of one hippocampal CA1 neuron (membrane capacitance = 5.2) to the application of three different concentrations of muscimol. Low concentrations of muscimol evoke sustained chloride (Cl sup -) currents during the application period, whereas a concentration of 75 micro Meter evokes a transient current. (B) Muscimol concentration-response curve showing that maximal Cl sup - currents are evoked at concentrations of >or= to 100 micro Meter. The concentration at which 50% of the maximal increase can be reached is [nearly =] 40 micro Meter. More variation in current is found with higher concentrations of muscimol. Each point represents the average value of 9, 13, 9, 17, 6, 17, 20, 21, 6, and 6 cells for concentrations of muscimol of 200 to 0 micro Meter respectively. Every cell was exposed to one concentration of muscimol. Bars represent SEM of these values.