Title: “Spatial propagation of slow wave brain activity during sleep”
Abstract: Transient high power waveforms at 0.5-2 Hz for a half-cycle or longer, known as slow waves (SW), are the defining feature of brain electrophysiology during deep sleep (NREM 2-4), and are believed to underlie a homeostatic process related to the regulation of use-dependent changes accumulated while awake. Many interesting relationships have been discovered linking the amplitude and quantity of SWs during sleep to memory, aging, and various neurological disorders; however, relatively little is understood about how SW activity is distributed throughout the brain. Less than a decade ago, SWs were believed underlie globally synchronous activity, but recent intracranial studies suggest instead that SWs tend to occur locally, and only occasionally involve the entire brain. There is also weak evidence from extracranial EEG suggesting that these waves propagate spatially. The current model might be summarized by saying: “SWs tend to be local events, which occasionally spread in an anterior to posterior direction.” To better describe the dynamic patterning of SW activity in the human brain, I investigate the spatio-temporal correlation of these waveforms on neuronal timescales recorded intracranially with 1-10 mm spatial resolution. I will present preliminary analyses and visualizations which suggest SWs are highly correlated in space and time, and form complex patterns which tend to propagate like traveling waves. I am requesting audience feedback to discuss how I might better quantify this phenomenon.