Figure 5. Bidirectional responses require calcium‐activated potassium channels.

A, examples (left) of synaptic responses of neurones from Thy1‐ChR2‐YFP mice to optical activation of inputs before and during block of BK channels with iberiotoxin (IBTX), and subsequent block with iberiotoxin and apamin. Population data (centre and right) indicate that iberiotoxin reduces the inhibitory component (V _inh: P = 0.046, n = 6, N = 6, paired t test) and that subsequent addition of apamin blocks the inhibitory component (V _inh: P = 0.006, n = 4, N = 4, paired t test). B, examples of synaptic responses to optical activation of inputs in Thy1‐ChR2‐YFP before and during block of SK channels with apamin. Population data (centre and right) indicate that apamin blocks the inhibitory component (P = 2.6 × 10⁻⁵, n = 9, N = 8, paired t test) while increasing the amplitude of the excitatory component (P = 7.3 × 10⁻⁵, n = 9, N = 8, paired t test). Data are presented as means ± SEM. ^* P < 0.05 (paired t test).