ERC-funded project: Dissociating mental imagery, working memory and conscious perception
Conscious experiences normally result from the flow of external input into our sensory systems. However, our minds are also able to create conscious percepts in the absence of any sensory stimulation; these internally generated percepts are referred to as mental images, and they have many similarities with real visual percepts; consequently, mental imagery is often referred to as “seeing in the mind’s eye”.
Mental imagery is also believed to be closely related to working memory, a mechanism which can maintain “offline” representations of visual stimuli no longer in the observer’s view, as both involve internal representations of previously seen visual attributes. Indeed, visual imagery is often thought of as a conscious window into the content of memory representations.
Imagery, working memory, and conscious perception are thus thought to rely on very similar mechanisms. However, in everyday life we are generally able to tell apart the constructs of our imagination from real physical events; this begs the question of how the brain keeps apart internal mental images from externally induced visual percepts.
To answer this question, the proposed work aims to isolate the cortical mechanisms associated uniquely with WM and imagery independently of each other and independently of the influence of external conscious percepts. Furthermore, by the use of neuroimaging and brain stimulation, we aim to determine the cortical mechanisms which distinguish between internally generated and externally induced percepts, in both health and disease.
This is a question of great clinical interest, as the ability to distinguish the perceived from the imagined is impoverished in psychotic disorders. This project aims to reveal the neuronal basis of this confusion, and to alleviate it in psychotic patients by the use of brain stimulation. The results will significantly improve our understanding of these important processes of human cognition and offer clinical insights.
This project is funded by €1.3 million ERC Starting grant awarded to Professor Juha Silvanto.
Publications
Jacob J, Jacobs C, Silvanto J (2015). Attention, working memory, and phenomenal experience of WM content: memory levels determined by different types of top-down modulation. Front Psychol. 6:1603. doi: 10.3389/fpsyg.2015.01603. eCollection 2015.
Saad E, Wojciechowska M, Silvanto J. (2015). Partial dissociation in the neural bases of VSTM and imagery in the early visual cortex. Neuropsychologia 75: 143-148.
Jacobs C, Silvanto J (2015). How is working memory content consciously experienced? The
'conscious copy' model of WM introspection. Neuroscience and Biobehavioral Reviews 55:510-
519.
Soto D, Silvanto J (2014). Reappraising the relationship between working memory and conscious awareness. Trends in Cognitive Sciences 18(10):520-5.