Scientists zap brain to unlock secrets of smell

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

* INCLUSION CRITERIA: In order to be eligible to participate in this study, an individual must meet the following criteria: 1. Aged 18-45 years old. Justification: Many neural processes change with age, and these changes could introduce unwanted variability in the measured signals. 2. In good general health based on the assessment of the Medical Advisory Investigator (MAI) or delegate. 3. Right-handed. EXCLUSION CRITERIA: Individuals who meet any of the following criteria will be excluded from participation: 1. Any neurological disorder that would increase seizure risk from TUS such as stroke, brain lesions, previous neurosurgery, epilepsy, any history of seizure or fainting episode of unknown cause, frequent severe headache, or head trauma resulting in loss of consciousness, lasting over 30 minutes or with sequela lasting longer than one month. The MAI will also retain discretion to exclude based on a history of a neurological illness or trauma that may compromise safety or data integrity. 2. Predisposition to seizures (e.g., first-degree family history of potentially hereditary epilepsy, etc.). 3. Current use (any use in the past week, daily use for more than one week within past 3 months) of any investigational drug or of any medications with psychotropic (e.g., benzodiazepines, etc.), or anti or pro-convulsive action. This will be determined at the discretion of the MAI. 4. Unable to undergo MRI, or TUS due to certain metallic or magnetic devices or implants in the body, claustrophobia, or other reasons including numbness or paresthesia of the head. 5. History of noise-induced hearing loss or tinnitus. 6. Recent history (within past 12 months) of learning disability, major DSM-5 psychiatric disorder including major affective disorder, ADHD, obsessivecompulsive disorder, schizophrenia, or PTSD. This will be determined at the discretion of the MAI. 7. Pattern of alcohol and drug use in the past 12 months that is indicative of harmful use, loss of control over use, or physical dependence. 8. Daily nicotine, alcohol, or drug use (excluding caffeine) for at least 4 continuous weeks within the past 12 months. 9. Participation in any neuromodulation (e.g., TMS, TUS, tDCS, tACS, etc.) session (excluding the current protocol) in the past two weeks. 10. History of anaphylaxis and/or severe food and non-food allergies (e.g., latex, detergents, soap, etc.). 11. History of significant chronic obstructive pulmonary disease (COPD) or severe, uncontrolled asthma, as increased levels of carbon dioxide may increase the susceptibility to cavitation and related tissue damage. 12. Uncorrected impairments in visual acuity severe enough to affect task participation. 13. Non-English speaking. Justification: Data integrity of some of the behavioral tasks used in this study would be compromised as they have only been validated in English. Most importantly, ongoing communication regarding safety procedures is necessary when participants are undergoing TUS and MRI procedures. The inability to effectively communicate TUS and MRI safety procedures in a language other than English could compromise the safety of non-English speaking participants. 14. Serious skin disease involving the hands or head, or history of serious systemic allergy involving the skin or mucous membranes such as Stevens-Johnson syndrome, or known history of contact dermatitis to ultrasound gel. Justification: Gel will be applied to the skin on both head and hands, for transducer coupling and electrode placement, respectively. Allergic or adverse reactions to such treatment need to be ruled out. 15. Hyposmia, i.e., decreased sense of smell, or anosmia, i.e., loss of smell (Sniffin' Sticks Olfactory Identification Score \< 10). Justification: The ability to smell is paramount to task performance. 16. Pregnancy. Justification: It is unknown whether MRI and/or TUS pose risks to fetuses. 17. Any other condition that in the judgment of the investigators is incompatible with participation.