Fos-positive cell counts in PC. Stimulation electrodes were targeted to the right NDB in all cases. By 45 min after an intraperitoneal injection of vehicle, saline, few Fos-positive cells were present in PC bilaterally in the absence of NDB stimulation (columns 1, 2). A significant increase in Fos-positive cells was observed in PC (column 4) after 45 min of NDB stimulation, as compared with controls. Note that the increase in Fos-positive cells in the unstimulated contralateral PC (column 3), however, was significantly less than in PC ipsilateral to the stimulated NDB. Pretreatment with the selective muscarinic receptor antagonist scopolamine before NDB stimulation significantly decreased the number of Fos-positive cells bilaterally in PC (columns 5, 6), as compared with stimulated animals lacking scopolamine pretreatment (columns 3, 4).