Rats were anaesthetized with isoflurane, decapitated and their brains quickly removed and chilled in ice-cold cutting solution (in mM: NaCl, 125; NaHCO3, 25; D-glucose, 11; KCl, 2.5; NaH2PO4.2H2O, 1.25; MgCl2, 2.5; CaCl2, 0.5) saturated with carbogen (95% O2/5% CO2). Coronal slices (280 μm) containing the amygdala were cut with a vibratome (Leica) and incubated for 1 h at 34 °C then allowed to equilibrate to room temperature prior to recording. For recording, slices were transferred to a recording chamber superfused at 2 ml min−1 with artificial CSF (aCSF) containing (in mM) NaCl, 125; NaHCO3, 25; D-glucose, 11; KCl, 2.5; NaH2PO4.2H2O, 1.25; MgCl2, 1; CaCl2, 2; saturated with carbogen and heated to 32–34 °C. Intercalated cells were visualized using an Olympus BX51 microscope equipped with × 40 water immersion objective and Dodt gradient contrast optics.