The aims of this study are threefold. First, to investigate whether spinal nociceptive processing - represented here by the nociceptive flexion reflex (NFR) - is influenced by thoracic transcutaneous spinal direct current stimulation (tsDCS) in a spatially selective manner, i.e., whether effects are only observed for lower limb NFRs, but not for upper limb NFRs. Second, to investigate - in a double-blind, sham-controlled, within-participant design - whether anodal and cathodal tsDCS do affect the NFR in a polarity-dependent manner. Third, to investigate whether tsDCS effects observed on a spinal measure (NFR) are also observed in responses that are mediated supra-spinally, namely autonomic parameters and pain intensity ratings.

Inclusion Criteria:

1. Healthy volunteers between the ages of 18 and 40 years
2. Having participated in the MRI medical assessment session and consented to taking part in 3T MRI measurements in written form
3. Having participated in the magnetic/electric neurostimulation medical assessment session and consented to taking part in magnetic/electric neurostimulation experiments in written form
4. Voluntary participation and signing of the study-specific consent form

Exclusion Criteria:

1. Existence of any contraindications for MRI measurements and magnetic/electric neurostimulation experiments
2. Pregnancy or breastfeeding
3. Very dry or sensitive skin (e.g., intolerance to creams/shampoos)
4. Chronic skin diseases - such as eczema or neurodermatitis - in the area of somatosensory / nociceptive stimulation (arm or hand, leg or foot) or electrophysiological data recording (upper body, arm, leg)
5. Scar tissue in the area of somatosensory / nociceptive stimulation (arm or hand, leg or foot) or electrophysiological data recording (upper body, arm, leg)
6. Acute sunburn in the area of somatosensory / nociceptive stimulation (arm or hand, leg or foot) or electrophysiological data recording (upper body, arm, leg)
7. Current or recurring pain
8. Injuries to the nervous system
9. History of or current neurological or psychiatric disorders
10. Chronic diseases that require permanent medication (e.g., asthma, diabetes mellitus, etc.)
11. Persons not capable of giving consent (e.g., in case of dementia)
12. Lack of consent with regards to report of incidental findings