When a crowd starts to applaud, each person initially does so to their own rhythm. But in some cases, those claps can synchronize, with hundreds or thousands or millions of hands striking in unison.
Something similar happens in the brain. When a single neuron fires, it sends an electrical pulse down its length. But large networks of neurons can also fire together, creating regular cycles of electrical activity that resemble the synchronized applause of a rapturous crowd. Formally, these are called neural oscillations; more colloquially, they’re brain waves.
These waves are classified by how frequently the neurons fire in a single second. If they fire one to four times, that’s a delta wave, which occurs during deep sleep. If they fire 12 to 30 times, that’s a beta wave, which is typical of normal wakefulness. And if they do so 30 to 90 times, that’s a gamma wave, which has been linked to higher mental abilities, like memory, attention, and perception. It’s no surprise, then, that scientists have seen disrupted gamma waves in many types of brain disorders, including injuries, schizophrenia, and Alzheimer’s disease.
But by studying mice, Hannah Iaccarino and Annabelle Singer have shown that these disrupted gamma waves aren’t just a symptom of Alzheimer’s. By restoring normal gamma waves, Iaccarino and Singer actually managed to counteract a hallmark of the disease. In Alzheimer’s, a protein called beta-amyloid gathers in the spaces between neurons, and creates large, harmful plaques. But gamma can apparently mobilize the immune system to clear these plaques.