Decision-making is an important process that is frequently shown to be impaired in patients with depression. While a number of preclinical and clinical studies have identified key regions involved in this process, it remains unclear exactly how these regions are influencing choice behavior especially when choices become more challenging. The goal of this project is to understand how these regions, such as the cingulate cortex, impact difficult choice behavior. Specifically, the researchers are interested in learning how disruptions in cognitive control might impact choice preferences during difficult decisions in depressed patients. To do this, this study will recruit participants with depression (as well as healthy controls) to perform game-like tasks in the laboratory while undergoing TMS or TI.
In recent years, countless studies have employed functional magnetic resonance imaging (fMRI) and other imaging modalities to both discover and track activity in brain regions involved in performance or behavior in a wide range of tasks. Running in parallel, research involving neuromodulation has afforded researchers the opportunity to test the impact of direct stimulation on areas hypothesized to be involved in certain processes or behaviors. Among such technologies are transcranial magnetic stimulation (TMS) and temporal interference (TI). TMS and TI can be performed during any sort of cognitive or behavioral task to estimate the effect of the stimulated brain area; as such, TMS and TI have an exciting array of potential applications in research. One area, for example, is cost-benefit decision-making. Because of the potential biases associated with self-report measures-including simple recall errors, misinterpretations of the item, and social-conformity pressures-a number of psychological laboratories have advocated for the use of decision-making tasks as an alternative means of assessing motivation and reward-related symptoms. Such tasks ask individuals to choose how much they are willing to work, wait, or risk to win various rewards. These measures have been used in a variety of behavioral and neuroimaging studies and in different clinical populations. This study will use TMS or TI in combination with a series of behavioral tasks to probe the relationship between areas known or hypothesized to be involved in cognition and/or cost-benefit decision-making, and performance on these tasks. This study aims to understand the effect of TMS or TI stimulation of certain brain areas on performance in a series of cognition- and decision-based behavioral tasks. To do so, the researchers will stimulate areas of the cortex hypothesized to be selectively engaged with cognition of a given category, or cost-benefit decision-making (depending on the behavioral tasks used). This study will examine healthy controls and depressed patients to investigate these effects. Such an aim will not only provide a deeper understanding of decision-making for basic research but will also hopefully inform understanding when decision-making is altered, as in psychiatric populations.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
500
Participants will be seated comfortably in a chair and asked to complete simple computer tasks. Participants will receive neurostimulation in the form of Transcranial Magnetic Stimulation (TMS) or Temporal Interference (TI). TMS: Either during, or just before any of the tasks, participants will receive either repetitive transcranial magnetic stimulation (rTMS) or single pulse TMS. During this, the researchers place a small plastic coil next to the participant's head. The coil will then generate a magnetic pulse, and stimulation will occur during presentation of the visual stimuli on which subjects will conduct behavioral or cognitive tasks. TI: Either during, or just before, any of the above tasks, participants will receive stimulation with TI. To do so, commercially available gel-based electrodes will be placed on the scalp to target the relevant brain region. The position targeted by the electrodes will be guided by previously defined coordinates.
Emory University
Atlanta, Georgia, United States
RECRUITINGStaggered Effort-Based Decision-Making Task
Assessment of reward motivation will be accomplished using an effort-based decision-making task modified for fMRI use. During each trial, subjects are presented with a choice between two levels of task difficulty, a High Effort option and a Low Effort option, which require different amounts of speeded manual button pressing for differing levels of monetary reward. The reward magnitude for a No Effort option remains constant ($1.00), while the reward magnitude for the High Effort option varies from $1.00 to $11.00. Additionally, the amount of effort required for the High Effort option will vary between 20%, 50%, 80% and 100% of the subject's max effort (set for each individual prior to scan). Multiple metrics of task performance will be compared between study arms.
Time frame: Day 1, during TMS/ TI stimulation
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