The frequency-dependent effect of electrical fields on the mobility of intracellular vesicles in astrocytes

Slow-wave sleep, defined by low frequency (<4 Hz) electrical brain activity, is a basic brain function affecting metabolite clearance and memory consolidation. Although the origin of low-frequency activity is related to cortical up and down states, the underlying cellular mechanism of how low-frequency activity becomes effective has remained elusive. We applied electrical stimulation to cultured glial astrocytes while monitored the trafficking of GFP-tagged intracellular vesicles using TIRFM. We found a frequency-dependent effect of electrical stimulation that electrical stimulation in low frequency elevates the mobility of astrocytic intracellular vesicles. We suggest a novel mechanism of brain modulation that electrical signals in the lower range frequencies embedded in brainwaves modulate the functionality of astrocytes for brain homeostasis and memory consolidation. This finding suggests a physiological mechanism whereby endogenous low-frequency brain oscillations enhance astrocytic function that may underlie some of the benefits of slow-wave sleep and highlights possible medical device approach for treating neurological diseases.