Fig. 2. Baseline responding for electrical stimulation of the paraventricular nucleus of the hypothalamus (PVN) and medial forebrain bundle (MFB) for control and spinal nerve-ligated (SNL) rats. Frequency-response curves for baseline responding were generated by averaging the second and third components preceding saline administration (before any drug treatments). The y-axis indicates the number of self-stimulations (0.5-s) per 60 s for each frequency (x-axis). Data shown are averages across control (n = 11, n = 7) and SNL (n = 12, n = 9) rats with PVN and MFB electrodes, respectively. Average current intensities during baseline responding were 246.82 (17.51) μA and 215.71 (26.87) μA for control rats and 234.58 (19.59) μA and 208.33 (18.86) μA for SNL rats with PVN and MFB electrodes, respectively.