Efficacy of kTMP, a Novel Non-invasive Brain Stimulation Method, for the Treatment of Anhedonia

Ventral striatal BOLD response during reward anticipation

To assess ventral striatal activation during reward anticipation, patients will participate in a Monetary Incentive Delay (MID) task while in an MRI scanner. We will measure the change in BOLD response during reward anticipation trials, comparing active and sham kTMP and the parametric effect of kTMP on the BOLD response.

The relationship between the level of ventral striatal engagement and clinical scores of anhedonia

For each patient, we will obtain the Snaith-Hamilton Pleasure Scale (SHAPS) scores and carry out a multiple regression analysis

Changes in scores of the Snaith-Hamilton Pleasure Scale (SHAPS).

The Snaith-Hamilton Pleasure Scale (SHAPS) is a well-validated 14-item questionnaire used to assess anhedonia. It asks participants to agree or disagree with statements of hedonic response in pleasurable situations.

The response bias in the Probabilistic Reward Task (PRT).

This task is designed to assess the propensity to modulate behavior as a function of reinforcement history and has been found to reflect reward-related function.

The motivation to pursue reward in the Effort Expenditure for Rewards Task (EEfRT).

The primary outcome measure in EEfRT is the proportion of high-effort, high-reward choices a participant makes with respect to low-effort, low-reward option, which indicates their willingness to expend effort to attain a larger reward.

Scores in the Visual Analog Scale of Anhedonia (VAS).

The Visual Analog Scale (VAS)-Anhedonia is a standard VAS assessment of anhedonia severity which provides a global anhedonia indicator.