# The Effect of Caffeine on Movement-Related Cortical Potential Morphology and Detection

## TL;DR

This study found that drinking coffee with 85 mg caffeine does not significantly change brain signals before movement but slightly improves brain-computer interface performance.

## Contribution

The novel contribution is identifying caffeine's minimal impact on MRCP amplitude and a small improvement in BCI classification accuracy.

## Key findings

- Caffeine consumption did not alter movement-related cortical potential (MRCP) amplitude.
- There was a slight 2% increase in classification accuracy after caffeine intake.
- Caffeine appears to be a minor confounder in MRCP-related studies.

## Abstract

Movement-related cortical potential (MRCP) is observed in EEG recordings prior to a voluntary movement. It has been used for e.g., quantifying motor learning and for brain-computer interfacing (BCIs). The MRCP amplitude is affected by various factors, but the effect of caffeine is underexplored. The aim of this study was to investigate if a cup of coffee with 85 mg caffeine modulated the MRCP amplitude and the classification of MRCPs versus idle activity, which estimates BCI performance. Twenty-six healthy participants performed 2 × 100 ankle dorsiflexion separated by a 10-min break before a cup of coffee was consumed, followed by another 100 movements. EEG was recorded during the movements and divided into epochs, which were averaged to extract three average MRCPs that were compared. Also, idle activity epochs were extracted. Features were extracted from the epochs and classified using random forest analysis. The MRCP amplitude did not change after consuming caffeine. There was a slight increase of two percentage points in the classification accuracy after consuming caffeine. In conclusion, a cup of coffee with 85 mg caffeine does not affect the MRCP amplitude, and improves MRCP-based BCI performance slightly. The findings suggest that drinking coffee is only a minor confounder in MRCP-related studies.