Table 1. Summary of the morphological and physiological properties of the three categories of PPN neurons.
| Neuronal type | Cell body area (μm2) | Total number dendritic beads | Number of local boutons | Axon origin | Total dendritic length (μm) | firing rate SWA (Hz) | firing rate AS (Hz) | CV SWA | CV AS | AP width (ms) | firing rate response to brain state transitions |
||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Increase | Decrease | No change | |||||||||||
| Quiescent neurons (n=5) | 277±28 | 18.8±9.3 | 36&11 (n=2) | Cell body (n=3) | 2514±478 | 0.27±0.1 | 1.75±0.9 | 1.13±0.13 | 0.59±0.16 | 0.95±0.02 | 3 | 1 | 1 |
| Tonic firing neurons (n=4) | 185±43 | 0 (n=3) & 46 (n = 1) | 0 | Secondary dendrite (n=3) | 2002±599 | 19.14±3.54 | 22.02±3.21 | 0.27±0.01 | 0.32±0.03 | 0.69±0.06 | 1 | 0 | 3 |
| Irregular firing neurons (n=8) | 225±27 | 40.6±22.9 (n=7) | 16&24 (n=2) | Primary dendrite (n=4) | 3534±443 | 2.62±0.27 (n=7) | 3.04±0.86 (n=7) | 0.71±0.15 (n=7) | 0.91±0.22 (n=7) | 1.01±0.08 (n=7) | 4* | 1 | 2 |
Displayed values are averages ± SEM for all neurons in each group unless otherwise stated.
*
Two of these neurons showed a bimodal response, that is, they decreased their firing rate following their initial increase.
AP, action potential; AS, activated state; CV, coefficient of variation; SWA, slow-wave activity.