Fig. 4.

A: effects of different lesions on maintenance of H-reflex down-conditioning. Average H-reflex sizes (±SE) for each 5-day period for corticospinal tract (CST)-transected rats (n = 5), DIN-ablated rats (n = 8), and IO-ablated rats (n = 12) for the first 50 days of down-conditioning before the lesion and for the next 50–100 days after the lesion [CST data from Chen and Wolpaw (2002); DIN data from Wolpaw and Chen (2006); IO data from present study]. For the 5 days immediately after lesion, H-reflex sizes are shown for the 1st day and the 2nd day (smaller symbols) and for the next 3 days together. All 3 lesions show a transient increase in the first 1–2 days (see footnote 1). After this brief nonspecific effect dissipates, all 3 lesions result eventually in an H-reflex larger than its initial control size. The H-reflex down-conditioning mode remains in effect throughout. B: this expansion from A shows average daily H-reflex values for the IO and DIN rats for the days immediately before and after IO or DIN ablation. In the DIN rats, the first stage of the H-reflex increase occurs within the first 2 days after DIN ablation; in the IO rats, it develops over the initial 10 days after IO ablation. [The brief nonspecific increase in the first 1–2 postablation days is evident for both ablations (footnote 1).]