| Test | Principle | Nerves assessed |
| Sweat test | Heat stimulates thermoregulatory center | Central sympathetic adrenergic and peripheral sympathetic cholinergic |
| BP lying, standing | Postural BP control by adrenergic nerves | Sympathetic adrenergic |
| RR interval with deep breathing | Vagal reflux bradycardia | Cardiac vagus |
| Plasma pancreatic polypeptide response to modified sham feeding | Sham feeding stimulates vagal center and efferents | Efferent vagus to abdomen |
