Summary: Using electrical fields to simulate slow wave sleep, researchers enhance memory.
Source: University of Alberta.
When it comes to remembering, brain-wave patterns during deep—or slow-wave—sleep could play a critical role, according to a new study by University of Alberta neuroscientists.
“During slow-wave activity, brain cells fire in all sorts of patterns, which we think represents the strengthening of memories during sleep,” explained Anastasia Greenberg, who led the research while completing her PhD with Clay Dickson, a professor in the Department of Psychology.
In the study, researchers simulated slow-wave sleep in lab models and attempted to modulate them using electrical fields. Previous experiments had shown that applied electrical fields can “boost” memories.
In collaboration with researchers at the University of Lethbridge, the team used an imaging technique employing voltage-sensitive dye to see activity across the brain. Results showed that the slow-wave electrical fields had a prominent effect on neural activity in the entire brain.
“The stimulation dramatically changed those activity patterns into new, previously unseen ones,” said Greenberg, who is now studying law at McGill University. “This means the electrical stimulation might be working in an ‘artificial’ way to enhance memories.”
“If you could influence the kind of slow-wave sleep you are having, maybe you could actually enhance memory,” added Dickson.
Does this mean students should schedule a nap after every study session or buy an electrical field simulator to use while they sleep? Not just yet. Future research is still required, explained Dickson.
“There’s a lot we still don’t understand, in part because it’s very difficult to measure activity in the brain while using an electrical field to produce the activity.”
Traditional methods of measuring brain activity, such as EEG technology, struggle to record activity during these types of tests. Using the imaging technology provided by U of L, Greenberg was able to bypass the issue altogether to determine how electrical fields change brain activity, and to characterize the activity as it happens.
“This technique allowed us to look at the effects of electrical field stimulation as it is happening in the brain. It’s the first time this kind of technology has been applied in this way,” said Dickson. “This collaboration has been invaluable.”
Funding: The research was conducted in collaboration with the U of L through a Campus Alberta Neuroscience trainee grant.
Source: Katie Willis – University of Alberta
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is credited to University of Alberta.
Original Research: Abstract for “New waves: Rhythmic electrical field stimulation systematically alters spontaneous slow dynamics across mouse neocortex” by Anastasia Greenberg, Javad Karimi Abadchi, Clayton T. Dickson, Majid H.Mohajerani in NeuroImage. Published May 3 2018.
New waves: Rhythmic electrical field stimulation systematically alters spontaneous slow dynamics across mouse neocortex
The signature rhythm of slow-wave forebrain activity is the large amplitude, slow oscillation (SO: ∼1 Hz) made up of alternating synchronous periods of activity and silence at the single cell and network levels. On each wave, the SO originates at a unique location and propagates across the neocortex. Attempts to manipulate SO activity using electrical fields have been shown to entrain cortical networks and enhance memory performance. However, neural activity during this manipulation has remained elusive due to methodological issues in typical electrical recordings. Here we took advantage of voltage-sensitive dye (VSD) imaging in a bilateral cortical preparation of urethane-anesthetized mice to track SO cortical activity and its modulation by sinusoidal electrical field stimulation applied to frontal regions. We show that under spontaneous conditions, the SO propagates in two main opposing directional patterns along an anterior lateral – posterior medial axis, displaying a rich variety of possible trajectories on any given wave. Under rhythmic field stimulation, new propagation patterns emerge, which are not observed under spontaneous conditions, reflecting stimulus-entrained activity with distributed and varied anterior initiation zones and a consistent termination zone in the posterior somatosensory cortex. Furthermore, stimulus-induced activity patterns tend to repeat cycle after cycle, showing higher stereotypy than during spontaneous activity. Our results show that slow electrical field stimulation robustly entrains and alters ongoing slow cortical dynamics during sleep-like states, suggesting a mechanism for targeting specific cortical representations to manipulate memory processes.