Fig. 4.

Low concentrations of Ni²⁺suppress burst firing by reducing the spike ADP. A, Intrinsically bursting CA1 pyramidal neuron from an SE-experienced animal in normal ACSF (a₁), after block of the burst discharge by perfusion of 50 μm Ni²⁺(b₁), and after washout (c₁). The slow depolarization underlying the burst was unmasked by delivering a brief (4 msec) hyperpolarizing current pulse immediately after the first spike (a₂–c₂). The time course of the ADP was similar ina₁ anda₂ (for comparison at larger magnification, see d). Adding 50 μmNi²⁺ to the ACSF reversibly suppressed the ADP (b₂,c₂; for comparison at larger magnification, see e). B, Regular firing CA1 pyramidal cell in a sham-control animal before (a) and after (b) application of 100 μm Ni²⁺. The ADP was not affected by Ni²⁺ (for comparison at larger magnification, see c).