Dense array EEG research on neurological disorders, such as epilepsy and schizophrenia, has suggested that, in some cases, the neuropathology of the disorder may be seen most clearly during sleep. To research the neurophysiology of these disorders, we need a better understanding of the neural mechanisms of normal sleep.

Much evidence suggests sleep, particularly deep, slow wave sleep, is crucial for consolidation of declarative memories. A 2006 study by Marshall, et al., showed that enhancing these slow waves in the brain via transcranial direct current stimulation (tDCS) significantly increased performance on a paired-associate memory test. Participants learned word lists before sleep, and then were asked to recall them when they woke up. They were able to remember even more words post-sleep they had than in the pre-sleep training, in both the tDCS and the Sham control sessions. This increase was higher in the tDCS group, where slow waves and slow spindle density were correspondingly enhanced, offering more evidence for the memory consolidation process that occurs in deep, slow wave sleep.

Marshall et al. (2006) chose two electrodes to introduce slow oscillations: F3 and F4. BEL would like to replicate these results, and compare them with an alternate location for stimulation in the temporal region. Preliminary results from our pilot work in mapping slow wave sleep suggest temporal source generators, while previous research had theorized that slow waves were generated in frontal regions. However, these researchers relied on an incomplete electrode array, which could have impaired their source localization. With EGI’s full dense-array 256-electrode EEG nets, we hope to challenge this theory and show that slow waves also emerge from temporal sources. We may find that memory could be further improved by inducing current in temporal regions of the brain, and this will aid in developing new treatments for sleep and memory enhancement.

Seizures in Sleep

In our studies of nocturnal onset seizures, we have observed the remarkable effect of seizures emerging from the normal neurophysiological phenomenon of cortical slow oscillations of sleep.

Brain waves and brain images.
In this image, a one-second epoch of EEG is shown for each of 256 channels, arrayed on the page as would be seen looking down on the head. The seizure is indicated by the large discharges (brain waves) at the top middle of the page (forehead). In the topographic map (circle at right), the blue region shows one of the discharges of the seizure (a negative wave), and on the left GeoSource MRI plot (Philips Neuro, shows the source of the discharge estimated in the medial frontal pole.

Contribute to science and learn about sleep!

Interested people are invited to participate in a home sleep study to increase our understanding of the different stages of sleep and how good sleep contributes to better memory.

For both Phase I and Phase II, studies will be conducted in the comfort of your own home after receiving the EEG device and instructions by mail. We will ask you to do an online memory test before and after sleep, and to record your brainwaves using the electroencephalograph (EEG) device during sleep.  In Phase I, study participants will collect EEG during sleep on three nights, one of which will involve passing low levels of harmless electrical current through electrodes attached to your head to enhance your slow wave sleep. Participants will receive $50/sleep session in Phase I. Phase II involves the memory test and EEG recording and stimulation nightly for 4 weeks. Participants will receive $25/sleep session for Phase II. 

To participate, you must be a generally healthy person between 21 and 85 years of age and be able to understand English. You must have no history of head trauma, insomnia, or neurological conditions, and must not be taking any drugs that may affect your EEG. You must have home internet access to participate.

By volunteering to participate in this study, you will be contributing to increase our understanding of the different stages of sleep and how good sleep contributes to better memory. Contribute to Science!

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To inquire about participating, please email 
or call 541-525-9798. Brain Electrophysiology Laboratory Company, LLC, Eugene, Oregon