Localizing the LC. In each panel, yellow indicates cylinder coverage (diameter = 1.65 cm), green crosshairs indicate the estimated location of LC determined by physiological properties of neurons recorded at that site, including waveform shape, phasic responses to surprising stimuli, low-frequency continuous discharge and decreased activity during periods of drowsiness (Clayton et al., 2004; Rajkowski et al., 1998; Rajkowski et al., 2004). A. Section taken perpendicular to the long axis of the recording chamber at a depth corresponding to the estimated location of the LC. B. Sagittal section. IC, inferior colliculus; IV, IVth ventricle. C. Coronal section.