(A) schematic diagram of eyeblink-related pathways in pond turtles (see text for details). Abbreviations: nV, trigeminal nerve; nVIII, auditory nerve; pV, principal sensory trigeminal nucleus; pVI, principal abducens nucleus; accVI, accessory abducens nucleus; nVI, abducens nerve. Calibration bar = 0.25 s, 50 µV. (B) A representative recording from a conditioned preparation in which a conditioned response (CR, arrow) was recorded as a burst discharge followed by an unconditioned response (UR, triangle). The occurrence of the CS and US are indicated. (C) Immunocytochemical labeling of principal (a) and accessory (b) abducens motor neurons, and axons in the auditory nerve (c) for BDNF from naïve tissue. Scale bar = 100 µm.