Figure 2 |.

The hypocretin and histamine systems in the mouse brain—origin and general projections. Red dots indicate the location and projections of hypocretin neurons. The blue dots and lines represent the location and innervations of histamine neurons. Mouse brain connectivity was mapped using hypocretin–Cre and histidine-decarboxylase–Cre mouse lines. Adeno-associated viral vectors expressing Cre-dependent enhanced green fluorescent protein was injected to trace axonal projections from both hypocretin (red) and histamine (blue) neurons. Abbreviations: HCRT, hypocretin neurons; HDC, histidine-decarboxylase-positive (histamine) neurons. Reprinted with permission. © 2014 Allen Institute for Brain Science. Allen Mouse Brain Connectivity Atlas [online]. Available from: http://connectivity.brain-map.org/.