This academic study investigates how MRI-compatible transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) influences stress regulation and episodic future thinking in healthy volunteers. Participants undergo one MRI session: combining stress induction, tDCS (real or sham), and functional and metabolic MRI measurements. The study aims to better understand how non-invasive brain stimulation affects the neurophysiological and psychological mechanisms involved in stress processing and future-oriented thinking.
The purpose of this study is to examine the modulatory effects of non-invasive brain stimulation on cognitive and emotional processes related to stress regulation and episodic future thinking (EFT). Healthy adult volunteers complete one MRI session. Participants were randomly assigned to active or sham stimulation. First, participants performed an fMRI-based baseline measurement of the EFT task. This task involves imagining specific future personal events in response to cue words presented on a screen and later verbally describing these imagined events outside the scanner. During the second part, participants complete the Montreal Imaging Stress Task (MIST) - a mental arithmetic paradigm with time pressure and negative feedback to induce acute stress. Immediately afterward, they receive MRI-compatible tDCS (active or sham) for 20 minutes while at rest. The active tDCS delivers 2 mA current through a 4×4 cm anode placed over the left DLPFC and a cathode over the contralateral orbitofrontal region. Sham stimulation follows the same setup with current ramping only at the onset and offset. Following stimulation, an ASL perfusion scan, MRS spectroscopy targeting the hippocampus, and a post-stimulation EFT fMRI task were conducted. Throughout the MRI scan, behavioral and psychometric data were collected, including questionnaires on rumination, personality, and mood, as well as physiological and biochemical measures such as salivary cortisol and heart rate variability (HRV). The primary goal is to assess whether active tDCS modulates the neural, endocrine, and behavioral correlates of stress and future-oriented cognition compared to sham stimulation.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
60
active non-invasive brain stimulation
Sham non-invasive brain stimulation
UZ Brussel
Brussels, Brussels Capital, Belgium
Specificity score of episodic future thinking
Specificity of episodic future thinking responses assessed using a standardized scoring procedure applied to imagined future events. Unit of Measure: EFT specificity score (units on a standardized scale)
Time frame: Baseline and immediately post-tDCS (single study visit)
Momentary mood ratings - fatigue
Self-reported tension measured using a visual analogue scale (VAS) Unit of Measure:Score on a 0-10 scale. A higher score means more fatigued.
Time frame: Baseline; immediately post-tDCS; and immediately post-EFT paradigm (single study visit)
Mean BOLD signal change during episodic future thinking
Mean blood-oxygen-level-dependent (BOLD) signal change during the episodic future thinking task, averaged across predefined prefrontal-limbic regions of interest. Unit of Measure: Percent signal change (or beta coefficients from the general linear model)
Time frame: Baseline and immediately post-tDCS (single study visit)
Momentary mood ratings -tension
Self-reported tension measured using a visual analogue scale (VAS) Unit of Measure: Score on a 0-10 scale. A higher score means more tensed.
Time frame: Baseline; immediately post-tDCS; and immediately post-EFT paradigm (single study visit)
Momentary mood ratings - vigor
Self-reported vigor measured using a visual analogue scale (VAS). Unit of Measure: Score on a 0-10 scale. A higher score means more vigor.
Time frame: Baseline; immediately post-tDCS; and immediately post-EFT paradigm (single study visit)
Momentary mood ratings - anger
Self-reported anger measured using a visual analogue scale (VAS). Unit of Measure: Score on a 0-10 scale. A higher score means more anger.
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Time frame: Baseline; immediately post-tDCS; and immediately post-EFT paradigm (single study visit)
Momentary mood ratings - depressed mood
Self-reported depressed mood measured using a visual analogue scale (VAS). Unit of Measure: Score on a 0-10 scale. A higher score means more depressed mood.
Time frame: Baseline; immediately post-tDCS; and immediately post-EFT paradigm (single study visit)
Momentary mood ratings - cheerfulness
Self-reported cheerfulness measured using a visual analogue scale (VAS). Unit of Measure: Score on a 0-10 scale. A higher score means more cheerfulness.
Time frame: Baseline; immediately post-tDCS; and immediately post-EFT paradigm (single study visit)
Momentary mood ratings - stress
Self-reported stress measured using a visual analogue scale (VAS). Unit of Measure: Score on a 0-10 scale. A higher score means more stress.
Time frame: Baseline; immediately post-tDCS; and immediately post-EFT paradigm (single study visit)
Hippocampal glutamate concentration
Hippocampal glutamate concentration measured using proton magnetic resonance spectroscopy (¹H-MRS). Unit of Measure: Institutional units
Time frame: Baseline and immediately post-tDCS (single study visit)
Hippocampal GABA concentration
Hippocampal gamma-aminobutyric acid (GABA) concentration measured using proton magnetic resonance spectroscopy (¹H-MRS). Unit of Measure: Institutional units
Time frame: Baseline and immediately post-tDCS (single study visit)
Hippocampal glutamine concentration
Hippocampal glutamine concentration measured using proton magnetic resonance spectroscopy (¹H-MRS).
Time frame: Baseline and immediately post-tDCS (single study visit)
Hippocampal N-acetylaspartate (NAA) concentration
Hippocampal N-acetylaspartate (NAA) concentration measured using proton magnetic resonance spectroscopy (¹H-MRS). Unit of Measure: Institutional units
Time frame: Baseline and immediately post-tDCS (single study visit)
Salivary cortisol concentration
Salivary cortisol concentration measured using biochemical assay from saliva samples. Unit of Measure: nmol/L (or µg/dL)
Time frame: Baseline, immediately post-tDCS, and immediately post-EFT task (single study visit)
Cerebral blood flow
Cerebral blood flow measured using arterial spin labeling (ASL) MRI. Unit of Measure: mL/100 g/min
Time frame: Baseline and Periprocedural (during tDCS)