Opportunities to sit and stand trigger equivalent reward-related brain activity.

A recent theory contends that behaviors minimizing energetic cost are rewarding (Cheval et al., 2018). However, direct experimental evidence supporting this theory is lacking. To fill this knowledge gap, we investigated the effect of energy expenditure on reward-related brain activity in a pre-registered study. This preregistered study included thirty-one participants who were equipped with an electroencephalography (EEG) cap and performed a monetary incentive delay task. After attempting to quickly respond to a target, participants were given feedback instructing them to retrieve a token (reward condition) or to wait (no reward condition). In half of the rewarding trials, participants stood up to retrieve a token, thereby increasing energy expenditure. In the other half, participants just had to extend their arm to retrieve a token, thereby minimizing energy expenditure. The contingent negative variation event-related potential (ERP) component preceding the motor response was used as an indicator of reward pursuit. The reward positivity ERP component time-locked to feedback onset was used to determine reward valuation. Results showed that response time, contingent negative variation, and the reward positivity were not influenced by energy expenditure (remaining seated vs. standing up). This null effect of conditions was confirmed using equivalence tests. These results do not support the theory of energetic cost minimization but the equivalent effect of sitting and standing on reward-related brain activity is new knowledge that could contribute to shed light on the neural processes underlying the pandemic of physical inactivity.
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