In this research study, healthy participants will receive ear stimulation during brain imaging. Ear stimulation will involve the study team applying small electrodes to the outer part of your left ear and administering small amounts of electrical stimulation that may cause you to feel a "tickling" sensation on your ear. Participants will receive four, 8-min ear stimulation sessions in the scanner, and the order of the sessions is randomly assigned to you.

Knowledge gained from this study will help us better understand how stimulation of nerves in your ear turns on different parts of the brain.

This study is attempting to understand whether 30-minutes of a new ear stimulation technology can reduce pain in healthy individuals. Participants in this trial will attend two experimental visits, during which they will receive ear stimulation during the intravenous administration (I.V.) of either saline or naloxone. During each visit, the amount of thermal pain participants can tolerate will be determined before and after ear stimulation. Brain scans will also be collected before and after ear stimulation. Each visit should last about 3 hours.

Hypermobile EDS and hypermobile spectrum disorder (collectively referred to as hEDS) are estimated to affect 1 in 500 individuals worldwide. hEDS patients have limited treatment options for their numerous symptoms that impact the quality of life. This clinical trial tests a new ear stimulation method in hEDS patients to determine if it may improve quality of life.

Early evidence suggests the benefits of post-stroke motor rehabilitation may be enhanced by applying electrical stimulation to the ear. This study aims to test the new approach of pairing ear stimulation with motor rehabilitation in the home setting in stroke survivors with upper limb motor function deficits.

Hypermobile EDS and hypermobile spectrum disorder (collectively referred to as hEDS) are estimated to affect 1 in 500 individuals worldwide. This study will enroll hEDS patients to test a new ear stimulation system to help reduce symptoms associated with hEDS, including pain and GI problems. Ear stimulation will be applied twice daily, for four weeks at home, and we will collect electronic behavioral data to track progress.