Figure 5. Differences in connectivity between cholinergic and non-cholinergic neurons.
A, reconstruction of the cell body, dendrites (black) and axon (red) of an individual cholinergic PPN neuron. The PPN is shown in grey. All cholinergic neurons have both ascending and descending axonal projections to several brain areas, including the centrolateral (CL) and parafascicular (Pf) nuclei of the thalamus, superior and inferior colliculi (SC and IC), basal ganglia (STN, subthalamic nucleus) and lower brainstem (PnO, pontis oralis and PnC, pontis caudalis). This cholinergic neuron fired in time with increases in cortical gamma oscillations (30–50 Hz; grey) during slow-wave activity (inset). B, reconstruction of the cell body, dendrites (black) and axon (blue) of an individual non-cholinergic PPN neuron. Most non-cholinergic neurons were identified as projecting preferentially towards the basal ganglia (SNR, substantia nigra pars reticulata). Scale bar: 1 mm.