A. ECl was calculated independently of the neuron being recorded as this value depends only on the chloride concentration in the
patch pipette (top row). The values of evoked PSP potentials from focally applied muscimol on the soma or dendrites of CA1
neurons in normal ACSF and during the interictal state in low Mg2+ ACSF were obtained. Note the more depolarized values in the dendrites. B. Observed Erev values during the preictalh and preictald states in the three neuronal groups with three recording solutions (normal chloride, 5 mm; high chloride, 30 mm; perforated patch). *Significant differences in values between the calculated ECl and observed Erev values during the preictalh state. †Significant difference in values between the three recording pipette solutions across the same neuronal group during
the preictalh state. ‡Significant difference between Erev values during the preictalh state and Erev values in the preictald state. All results are shown as mean ± s.e.m.