Neuromodulation of Lidocaine and Capsaicin Cream Effects on Pain Experience

Neuromodulation of Placebo and Nocebo Effects

The aim of this study is to use a brain stimulation tool called transcranial direct current stimulation (tDCS) to investigate the analgesic (reducing sensitivity to pain) effects of lidocaine cream and the hyperalgesic (increasing sensitivity to pain) effects of capsaicin cream using a neutral cream as a control. tDCS stimulation has been shown to temporarily influence the way the stimulated part of the brain functions. With this method, the involvement of specific parts of the brain can be investigated in the working of the brain as a whole.

Inclusion Criteria:

• Right handed healthy male and female adults aged 21-50
• No contraindications to fMRI scanning
• At least a 10th grade English-reading level; English can be a second language provided that the patients feel they understand all the questions used in the assessment measures.

Exclusion Criteria:

• Current or past history of major medical, neurological, or psychiatric illness
• Claustrophobia
• History of head trauma
• Instability of responses to experimental pain
• Non-fluent speaker of English
• Presence of any contraindications to fMRI scanning. For example: cardiac pacemaker, metal implants, fear of closed spaces, pregnancy
• History of alcohol/substance abuse