Table 3.

Anatomical findings for the NA system in early sensory areas.

Structure	Species	Significance	Reference
V1	Squirrel monkey	Noradrenergic projections preferentially to layers 5 and 6 of V1	Morrison et al., 1982a; Lewis et al., 1987
V1	Macaca fascicularis	NA innervation much sparser than for 5HT, and least dense in layer 4C	Kosofsky et al., 1984
V1	Cynomolgus monkey	NA fibers less pronounced than 5HT. Weak in layers 1 and 2, and absent in layer 4Cβ	Kosofsky et al., 1984
V1	Rat	Decreasing fronto-occipital gradient of NA	Kehr et al., 1976
LGN	Squirrel monkeys and macaca fascicularis	Almost no noradrenergic innervation in the LGN	Morrison and Foote, 1986
LGN	Rat	NA fibers preferentially in the dLGN compared to vLGN and IGL (compared to 5HT fibers preferentially in the vLGN and IGL)	Papadopoulos and Parnavelas, 1990
S1	Squirrel monkey	Labeling in all layers	Morrison et al., 1982b; Lewis et al., 1987
S1	Rhesus monkeys	NA concentration highest in somatosensory cortex, lowest in V1	Brown et al., 1979
A1	Macaca fascicularis	Sparse innervation (substantially less dense than 5HT or Ach), lowest density in layer 4	Campbell et al., 1987
Olfactory bulb	Rat	Virtually no labeling fibers in the glomerular layer (first input stage) but fibers preferentially in the internal plexiform, granule cell, and external plexiform layers	McLean et al., 1989
IC, CN	Rat	LC heavily innervates both structures	Klepper and Herbert, 1991