Figure 6. Local connectivity in the PPN mediated by cholinergic neurons.
A, the same cholinergic neuron reconstruction shown in Fig. 5A at a higher magnification. Local axon collaterals (in black) of cholinergic neurons were typically studded with many varicosities (black dots). B, electron micrograph of one of the varicosities of the same neuron (b) establishing a synapse (arrow) with a dendrite (d) in PPN. C, cholinergic neurons (n = 10) have a large number of local varicosities, compared to the scarce number of local varicosities from non-cholinergic neurons (n = 6). Scale bar: 500 nm.