DCT based multi-head attention-BiGRU model for EEG source location

Electroencephalogram source imaging (ESI) pertains to localize brain sources. Due to the one-to-many relationship between electroencephalogram (EEG) signals and brain sources, ESI becomes a complex inverse problem with poor conditioning, leaving a lot of research space. This article proposes an enhanced multi-head attention (MA) and discrete cosine transform (DCT) based Bidirectional Gated Recurrent Unit (BiGRU) (MA-DCT-BiGRU for short) for addressing the EEG inverse problem. Initially, EEG signal characteristics are captured employing multi-head attention with the inclusion of average hidden states. Then, the DCT is used to project brain source signals into the low, medium, and high frequency subspaces composed of spatial frequency basis vectors. The spatial low-frequency component serves as a filter for extended source reconstruction. Subsequently, BiGRU is employed to learn the mapping from the output of the attention layer to the low frequency DCT coefficients of the brain-derived signals. The simulation results undeniably establish the superiority of the MA-DCT-BiGRU configuration in comparison to other state-of-the-art (SOA) methods for source recovery, irrespective of the source modes and signal-to-noise ratio conditions. Experimental results, utilizing both synthetic and actual epilepsy data, clearly demonstrate the effectiveness of the framework presented in this article for epileptogenic area localization.