Fig. 2.

Effects of cyproheptadine on estimated persistent inward current (PIC). A: instantaneous firing rate of lower threshold control (bottom) and higher threshold test motor units (top) during isometric dorsiflexion before (left) and 60 min after (right) oral intake of 8 mg of cyproheptadine in an iSCI participant (imp/s, impulses per second). The thick black line represents a 5th-order polynomial fit through the firing rate points. Dashed vertical lines mark the time of occurrence of recruitment and derecruitment of the higher threshold test unit. Solid horizontal lines indicate the firing frequency of the control unit when the test unit was recruited and derecruited, with the magnitude of difference in the firing rates between the 2 time points (ΔF) marked by the arrow. B: average ΔF expressed as a percentage of the predrug values at different time points across the 6 iSCI participants tested (subjects 3F–7M and 9M, Table 1). Error bars represent means ± SE. *P < 0.05.