How the brain prepares for gains and losses using EEG and fMRI
The brain's anticipation of winning or losing money relies on a shared motivational system rather than separate reward and loss networks.
Source
P300 amplitude variation is related to ventral striatum BOLD response during gain and loss anticipation: an EEG and fMRI experiment
What they did
The researchers tested 25 healthy, right-handed participants across separate EEG and fMRI sessions separated by an average of 50 days. During both sessions, participants completed a task where they saw visual cues signaling a potential gain of 2 euros, a potential loss of 2 euros, or a neutral outcome of 0 euros before responding quickly to a target. The team measured electrical brain responses (such as P300 and CNV waves) and BOLD signals in the ventral striatum to analyze how they relate.
What they found
Both gain and loss anticipation triggered similar activity in the ventral striatum and produced similar reaction times. Larger P300 wave amplitudes were significantly correlated with stronger BOLD responses in the ventral striatum for both gain and loss conditions, with correlations ranging from 0.420 to 0.767. In contrast, the slower CNV wave did not show any significant correlation with ventral striatum activity.
The limits
What it doesn't show
First, because EEG and fMRI data were collected in separate sessions rather than simultaneously, the study cannot rule out differences in the participants' mood or alertness between the separate test days. Second, because the study only measured blood flow and electrical scalp activity, it cannot provide direct evidence of dopamine release, even though the authors suspect dopaminergic pathways are involved. Finally, the small sample of 25 young, healthy participants restricts the generalizability of these findings to clinical populations.
Key terms
- Ventral striatum
- A deep brain region, including the nucleus accumbens, that plays a key role in motivation, reward processing, and decision-making.
- P300
- A positive electrical brain wave that peaks between 300 and 600 milliseconds after a stimulus, reflecting attention and the perceived salience of an event.
- Contingent Negative Variation (CNV)
- A slow, negative-going electrical brain wave associated with anticipation, attention, and preparation for motor effort.
- Monetary Incentive Delay (MID) task
- A psychological test where visual cues signal potential monetary rewards or losses, requiring quick motor responses to secure or avoid them.
- BOLD response
- A functional MRI signal that measures changes in blood oxygen levels to infer local neural activity in specific brain regions.
- Salience
- The feature of a stimulus that makes it stand out from its surroundings and attract cognitive attention.
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Quiz yourself
According to the study, what are the two temporally distinct stages of reward processing?
Common questions
Why did the researchers study both EEG and fMRI instead of just one?
Functional MRI (fMRI) has excellent spatial resolution, allowing researchers to pinpoint exactly where activity happens deep in the brain (like the ventral striatum), while EEG has excellent temporal resolution, showing electrical changes millisecond-by-millisecond. Combining them helps link quick electrical brain waves on the scalp to deeper, slower metabolic activity.
Did participants actually win or lose real money during the study?
Yes, participants started with 12 euros and could win or lose 2 euros per trial based on their performance, ending up with an average payout of 12.92 euros.
How does this study challenge older views of the ventral striatum?
Traditionally, the ventral striatum was labeled purely as a reward center. This study shows it is also highly active when anticipating a loss, suggesting it acts as a general motivational hub for action rather than just a detector of positive outcomes.
Why were the EEG and fMRI sessions done separately instead of at the same time?
Conducting the sessions separately allowed the researchers to optimize the task design specifically for the constraints of each technology, even though it introduces potential differences in participant state between the test days.
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