Imagine listening to a recording of an orchestral performance, but because of a bad studio technician, the only instrument you can hear is the triangle. How would you know if you were listening to the opening score to Star Wars, or to a really, really stuffy version of "Shake It Off"?
You couldn’t, because the experience of the music relies on hearing all those instruments playing together at the same time. And according to a new study in Nature, neural ensembles, like music bands, "play" together repeatedly to rapidly recreate "the same activation sequences that occurred during the original experience." In other words, neural replay transforms experience into memory.
But did you see the word navigation above? It’s there because senior author Michael Yartsev and colleagues drew their conclusions about neural replay by wirelessly recording the brain activity of bats in flight.
By using wireless probes connected to the hippocampi of six Egyptian fruit bats during aerial food-foraging, Yartsev’s team has pioneered the breakthrough recording of pings not from individual bat neurons, but simultaneously from groups of hundreds of them. Such data-collection may one day lead to curing human neurological diseases and improving human memory.
"Musicians" who play together, stay together
"For the past 20 years, we’ve been recording single neurons in bats and asking the question, 'When animals are doing interesting things, what do individual neurons do?'" said Yartsev, an associate professor of neuroscience and bioengineering from the University of California at Berkeley.
So, going beyond the "notes" and "rhythm" of a single neuron playing, Yartsev and colleagues "listened" to the "music" of hundreds of neurons pinging simultaneously in free-flying bats during replay sequences and theta sequences. Theta sequences are the ping-patterns formed during movement, especially when animals look forward during motion, and even before they move, implying theta sequences may assist in planning.
What's more, theta sequences exist inside the place cells of hippocampi in many animal species, which ping when animals are in specific locations, allowing them to map territory. When scientists detect a place cell pinging, they can infer the bat’s location from that ping. Pinging from multiple place cells indicates a flight path.
Bats: A treasure-horde of scientific knowledge inside their structures and cells
While mice and rats are the most well-known of experimental animals, bats are endless fascinating creatures that yield enormously valuable information about numerous subjects New Atlas has covered, including how bat evolution could lead to new treatments for viruses and aging and how bat echolocation served as the model for a new pipeline inspection system.
In addition to their importance as possessing powerful memory storage – enough that they can recognize ringtones tied to food rewards up to four years later, bats are also rich inspiration for biomimicry, as with Brown University’s robotic bat wings, Caltech’s bat-bot, and the non-flying wheeled Robat that uses ultrasonic microphones and a speaker to navigate via sonar.
How will understanding bat neurons improve human life?
As scientists such as Yartsev unlock the secrets of replay and theta sequences in animals such as bats, they may be able to improve our understanding of long-term memory storage and formation in humans. Doing so may help treat or even cure devastating neurological disorders such as Alzheimer’s and Parkinson’s disease.
If the scientists are successful, we all may have many more years to enjoy all that bat-inspired technology ... and if our bat friends decide to give us rabies, at least we’ll have enough capacity to remember to look for that inexpensive rabies cure from transgenic tobacco plants.
