FIG. 7.

Pharmacology of averaged PSPs elicited from antidromic stimulation of motoneurons via the ventral root. A: a depolarizing response was present (black trace) that persisted and was enhanced in 0 Ca²⁺ Ringer (red trace). Subtraction reveals a hyperpolarizing component (green trace) present in the control. B: in some neurons a depolarizing response was masking a strychnine-sensitive hyperpolarizing potential. Control PSP shown in black and after 5 μM strychnine in red. C: in this example ventral root stimulation evoked a hyperpolarizing potential in a CCIN (locomotor interneuron consisting of both inhibitory and excitatory types), which was abolished with strychnine. D: hyperpolarizing responses were also sensitive to nicotinic receptor blockade, as shown in this example from a giant interneuron. All data are averages of ≥30 traces.