tVNS and Approach-Avoidance Behavior in Anhedonia and Anxiety

Summary

This study investigates if anhedonia and anxiety symptoms are associated with alterations in reinforcement learning, effort trade-offs for wins vs. punishments, and foraging behavior under threat. Moreover, it will investigate whether these processes can be influenced by a metabolic load and/or transcutaneous vagus nerve stimulation (tVNS). The project consists of (a) an online reinforcement learning study, used to characterize learning, reward sensitivity, and meta-cognition, and (b) a laboratory study in which participants first undergo fMRI while completing an effort-based decision-making task. Second, participants will complete two sessions in VR with randomized active or sham tVNS during a foraging task before and after a caloric load with concurrent physiological recordings.

Eligibility

Inclusion Criteria:

* BMI between 18,5 and 30,0 kg/m2,
* between 18 and 40 years of age, and
* be able and willing to provide informed consent.

Exclusion Criteria:

* have a high risk of suicide,
* have a lifetime diagnosis of severe neurological disorder (incl. ADHD), schizophrenia, bipolar disorder, or severe substance abuse, posttraumatic stress disorder, obsessive-compulsive disorder, diabetes, epilepsy, or coronary heart disease
* have fulfilled criteria for an eating disorder or somatic symptom disorder within the last 12-months,
* take medication (except psychopharmacological medication for MDD or anxiety), patients have to be on stable psychopharmacological medication for at least two months before study participation (minimizing confounding effects)
* contraindications for MRI (metal implants or claustrophobia)
* for female individuals if they are pregnant or nursing at the time,
* impaired movement ability or hearing
* impaired, uncorrected vision (need contact lenses)
* contraindications for tVNS hearing aids or diseased skin on the right ear.

Conditions6

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