Figure 5.

Temporal course of ascending arousal system nuclei activation during appetitive behavior induced by enticing hungry rats with unreachable food. The level of neuronal activity, evaluated by Fos expression, is indicated by the grayscale. The four bar graphs correspond to rats that have fasted for 24 h and were sacrificed immediately before the beginning of the enticing procedure (time 0) or killed after the indicated times (30–120 min). Note that the first nucleus to increase Fos-ir 30 min after the beginning of enticing was the TMN. The other arousal nuclei increased Fos-ir after 60 min and continued with medium to high Fos-ir at 120 min. DR, dorsal raphe; LC, locus coeruleus; LDT, laterodorsal tegmental nucleus; Orx, orexin neurons from the lateral/perifornical hypothalamic area; TMN, tuberomamillary nucleus. Modified from Valdes et al. (2005).