Encoding Induced Alpha EEG Activity Reveals Visual Working Memory Representations and their Manipulations

Abstract

Until recently, the fields of visual working memory and imagery have independently studied the cognitive representation of visual information. It remains unclear, however, whether the representation of information during working memory and mental imagery are mediated by similar mechanisms, or whether they represent distinct processes. Previous studies have reconstructed orientation selectivity profiles from induced alpha-band (8 – 12 Hz) oscillations of electroencephalographic (EEG) data, enabling the identification of the contents held in visual memory. In an attempt to draw a bridge between these two fields, this thesis examines whether the induced alpha activity that has been shown to mediate the representation of orientations held in visual working memory can be used to track an imagery manipulation of these representation via a mental rotation. The results replicate previous findings, revealing that induced posterior alpha-band activity contains sufficient information that allows for the identification of the representation maintained in working memory. Furthermore, the reconstruction of orientation selectivity profiles revealed reliable changes in the mental representation during the imagery manipulation, although without being able to reliably decode the direction of the rotation. These results begin to bridge between isolated fields, indicating that these mental representations may depend on similar neural processes.