Interpretability of CNN-Based EEG Decoding During Mirror Box Training: A Pilot Study Using CWT Spectrograms and Explanaible AI

Abstract

Neural networks are increasingly applied in brain-computer interface research; however, their decision-making process is often considered difficult to interpret. This pilot study investigates whether a convolutional neural network can provide not only accu- rate but also neurophysiologically meaningful classification of electroencephalogram signals recorded during mirror box training. Two conditions, rest and left hand movement, were analyzed with a focus on interpretability. EEG signals from contralateral electrode C3 were transformed into time-frequency representations using the Continuous Wavelet Transform, and the resulting spectrograms were used as input to the convolutional neural network (CNN). To interpret the model’s decisions, Gradient-weighted Class Activation Mapping and other methods were applied, enabling identification of discriminative time-frequency regions. By relating these pat- terns to established neuroscientific knowledge, we assess whether the model relies on physiologically meaning- ful features, providing insight into brain dynamics during mirror-induced motor activity and supporting inter- pretable BCI applications.


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