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. Author manuscript; available in PMC: 2015 Aug 1.
Published in final edited form as: Hear Res. 2014 Jun 7;314:51–59. doi: 10.1016/j.heares.2014.05.004

Figure 4.

Figure 4

Diagram summarizing known and unknown circuit and molecular components of the CC pathway. Only the LC is shown in detail for clarity. Left: Layer 5 pyramidal cells (triangles) and layer 6 nonpyramidal cells (ovals) from AI and AII project to the LC. The specific contributions of layers 5 and 6 are not known and denoted with question marks. AII projections are more superficial than AI projections (Herbert, Aschoff and Ostwald 1991; Winer et al. 1998). Intrinsic excitatory cells of the IC are shown in blue. The black cell is a GABAergic neuron. Unknown connections to the CNIC and to GABAergic neurons are denoted with question marks. Right: Mosaic molecular organization of the LC. Layers 1 and 3 stain for VGLUT1. Layer 2 modules are positive for GAD67, AChE and NADPH-d. Layer 2 extramodular regions are positive for circumferential axo-somatic VGLUT2 profiles (A-S VGLUT2), thought to be seen on giant GABAergic tectothalamic neurons (Ito, Bishop and Oliver 2009). The question mark denotes the uncertainty about how the CC projections map onto the molecular heterogeneities across and within layers.