Oscillations in Reward-guided Behavior

Study Overview
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Brief Summary
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While people are reading, talking or playing computer games, their brain cells elicit electrical signals so they could perform these actions. The firing of these cells is not random but is organized in a temporal pattern, such that a group of cells are simultaneously active at a particular frequency. The researchers can read the frequency of brain signals and identify their location using different brain-imaging tools like EEG and fMRI. These methods are applied to healthy individuals and do not pose any danger. The investigators of this project would like to use these techniques to study the brain signals, while healthy participants are making the decisions choosing between 2 rewards, e.g., 2 food items. Participants who have depression show different behavior while performing decision-making tasks and the investigation of processes that underlie them will lead to a better understanding of this disease. Furthermore, there is another category of tools, which help to study the brain. This category includes electrical stimulation, which mimics the electrical pattern that brain cells elicit. Application of external electrical stimulation can enhance this pattern or disrupt it and this process will affect the behavior of a person. Recent investigations have led to the development of a new stimulation technique that allows targeting deep brain regions. The investigators of this project want to apply this method to change the performance of healthy participants in the tasks on decision-making. If this experiment is successful, then stimulation can be used as a therapy for participants with depression.

Official Title
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Investigating the Role of Brain Oscillations in Reward-guided Behavior

Conditions
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Reward-guided Behaviour

Intervention / Treatment
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* Device: TI transcranial electrical stimulation


Participation Criteria
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Eligibility Criteria
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General Inclusion Criteria: signed informed consent Age 18-40 years Normal physical and mental status (i.e. no neurological, musculoskeletal, neuromuscular, cognitive, or psychiatric disorders) If a participant already took part in the experiment with the same decision-making task Exclusion Criteria for TI electrical stimulation: pregnancy epilepsy head traumas implants (cochlear, neurostimulators, cardiac pacemakers, medication infusion device) metal in the brain or skull work in the metal industry scars or inflammations on the regions, where the stimulation electrodes are placed administration of antipsychotic or anti-epileptic medication hearing problems or ringing in the ears syncope or fainting spells in the last 5 years severe side-effects after transcranial magnetic stimulation (TMS) or electrical stimulation if participant underwent it before the inability to comply with magnetic resonance imaging (MRI) inclusion criteria if participant underwent it before Exclusion Criteria for MRI experiments: pregnancy claustrophobia history of brain surgery family member that suffers from epilepsy suffering from medication abuse for more than a year or drug intake taking medications for medical reasons for more than a month receiving of depot injections one or more of the following materials in the body: metallic objects (e.g., dental implants, a metallic splinter in the eye, but not braces); wire, pacemaker or implanted defibrillator; artificial heart valves; vascular grafts; bio-stimulator or nerve stimulator; aneurysm or intracranial clip; cochlear implant; other prostheses or orthoses; implanted medication pump (insulin or pain pump); medicated patch (e.g., nitro-patch, pain patch, nicotine patch, hormone patch, motion sickness patch); other implants; tattoo or jewelry history of any of these illnesses: brain thrombosis, stroke, traumatic brain injury, meningitis, heart attack, prolonged loss of consciousness, migraine, epilepsy

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Interventional Model Description: The same participants receive placebo/sham stimulation and active stimulation on different sessions separated with 1 week or within the same session. The sequence of sham/placebo and active stimulation will be randomized.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: TI stimulation<br>Temporal interference (TI) stimulation is a type of low-intensity transcranial electrical stimulation with alternating current (tACS). In case of TI stimulation, 2 electric fields in kHz range are delivered to 4 electrodes, which are placed on the surface of the skull, to modulate neural oscillations. | Device: TI transcranial electrical stimulation<br>* Participants will undergo transcranial electrical stimulation, which will be delivered with low current amplitudes (<= 2 mA) established with international safety guidelines for electrical stimulation. Threshold for the current amplitude will be established by participants themselves, such that they cannot distinguish when stimulation is applied and not applied. Duration of stimulation will not last longer than 30 minutes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Accuracy | Accuracy will be collected with a keyboard and a mouse | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 
| Reaction time | Reaction time will be collected with a keyboard and a mouse | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 
| Fixations | Fixations of the gaze on the screen will be recorded with an eye-tracker. | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 
| Saccades | Saccades (a type of the eye movement) will be recorded with an eye-tracker. | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 
| Blood oxygenation level dependent (BOLD) | BOLD signal is measured with functional magnetic resonance imaging (fMRI) experiment. | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 
| Brain oscillations in delta band | Oscillations within the range from 0.5 Hz to 4 Hz will be measured with electroencephalography (EEG). | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 
| Brain oscillations in theta band | Oscillations within the range from 4 Hz to 8 Hz will be measured with EEG. | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 
| Brain oscillations in alpha band | Oscillations within the range from 8 Hz to 12 Hz will be measured with EEG. | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 
| Brain oscillations in beta band | Oscillations within the range from 12 Hz to 30 Hz will be measured with EEG. | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 
| Brain oscillations in low gamma band | Oscillations within the range from 30 Hz to 70 Hz will be measured with EEG. | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 
| Brain oscillations in high gamma band | Oscillations within the range from 70 Hz to 250 Hz will be measured with EEG. | Continuously while participants perform a cognitive task (circa 2 hours) with and without TI stimulation. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Brain oscillations, Neural oscillations, Transcranial electrical stimulation tCS, Temporal Interference stimulation TI, Decision-making