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Multisensory stimuli and virtual navigation tasks during intracranial clinical recordings

Background

A picture of a first-grade classroom or the smell of fresh-baked cookies can evoke specific and detailed memories. These detailed memories often contain a comprehensive sensory scene - recalling sights, smells and sounds as well. The multisensory content of each memory involves the activity of many areas across the brain, and this collaboration of different areas in a specific memory is reinforced by sleep.

We understand more and more about the microscopic processes involved in storing memories, but we are still unclear how the activity of distributed neural populations is orchestrated into specific and coordinated patterns. As we learn more about the large-scale organization of memory consolidation, we deepen our basic understanding of human memory. We also shed light on future approaches for enhancing or disrupting consolidation of newly formed memories.

The Problem

In the two-stage model for memory consolidation, memories are first formed in an area known as the hippocampus and then transferred to a different area, the neocortex, for long-term storage. While it has become increasingly clear that certain kinds of brain activity during sleep contribute to this process, we don't understand how yet. The key missing piece is a mechanism to guide specific connections to strengthen during sleep-dependent long-term memory consolidation.

The Project

In this project, we will analyze recordings of neural activity under varying memory loads. While bursts of brain activity during sleep, known as 'sleep spindles', have been studied for quite a long time, we recently discovered that they are organized into waves that travel around the cortex. Our hypothesis is that these waves of activity help to organize neural activity in different areas of the brain. To test this, we will develop a virtual-reality (VR) navigation task and real-time, closed-loop sensory stimulus delivery system which will allow presentation of sensory stimuli (auditory cues paired during a learning task) timed to specific rhythms during sleep. We will then study EEG recordings from research participants at BMI and intracranial (iEEG) recordings from clinical patients at LHSC during sleep following learning in a virtual reality navigation task.

Results from this research will not only consolidate a new and fruitful avenue of collaboration between clinical, cognitive, and computational neuroscience at Western, but will also illuminate the underlying mechanism for consolidation of whole, coherent memories in the networks of the neocortex.

Western Researchers Lyle Muller Ana Suller-Marti Laura Batterink Julio Martinez-Trujillo David Steven

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