Experts believe that while we sleep, our brains replay the events of the day, moving information from the location of short-term memory, the hippocampus, to the long-term memory located in the neocortex. Slow waves” are especially key to this process: slow, synchronous oscillations of electrical voltage in the cortex that occur during the deep sleep phase. They can be measured using an electroencephalogram (EEG). The waves originate when the electrical voltage in many neurons rises and falls simultaneously once per second. To “listen in” on the communications among multiple nerve cells connected through the tissue, they used up to ten “pipette feelers” at once — an extra large number for this method, which is known as the multipath technique. During that brief time window, the cortex can be thought of as having been placed in a state of elevated readiness. If the brain plays back a memory at exactly this time, it is transferred to long-term memory especially effectively. So, slow-wave sleep evidently supports memory formation by making the neocortex particularly receptive for many short periods of time.” This knowledge could be used to improve memory, for example in mild cognitive impairment in the elderly. Research groups around the world are working on methods of using subtle electrical impulses — transcranial electrostimulation — or acoustic signals to influence slow waves during sleep. Slow waves, or slow oscillations, are a type of electrical wave arising in the brain during deep sleep. “Delta” waves comprise a certain frequency range that shows up in an EEG. These are slow brain waves that can arise outside sleep as well, as part of a disease or disorder. This broader term is sometimes used synonymously with the term “slow waves.
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Saturday, January 18, 2025