The visual information that a fly’s brain receives while in action is filtered in a way that eliminates potentially misleading signals. This is what a study by scientists at Rockefeller University has found by measuring electrical activity in individual neurons in their brains.
The brain has the ability to tell whether or not motion is self-generated and can cancel out information that might otherwise cause us to feel (and act) as if our surroundings were spiraling out of control. The Rockefeller team is attempting to decode this neural information in fruit flies and find out how the brain processes visual information to control behavior.
You are shifting your gaze several times per second. The brain then sends commands to your eyes to move. An internal copy of that command is issued to the brain’s own visual system. It is then able to predict that it will receive a flood of visual information resulting from body movement and to compensate for it by suppressing/enhancing the activity of the particular neurons. There are about 80 billion neurons in the human brain. So, the task of determining precisely how it makes these predictions and alterations to our human perception at a cellular level becomes extremely complicated.
That’s where the fruit fly comes in. It performs the same kinds of rapid eye movements. It’s teeny tiny brains only contain approximately 100,000 neurons handling the same problems of prediction and perception. Hence, it is at a scale that the Rockefeller team can capably research and record results from in fine detail.
Of course, there are a gazillion ways that fly eyes differ from human eyes. But the fly’s eyes still must have reflexes, urges, and calculated judgements made at a rapid speed as reactions to a multitude of environmental shifts and changes. They must be able to maintain their focus on particular targets while sorting through these ever-changing conditions. This gives scientists a great way to study how signals are sent, received, saved, relayed, and omitted while encountering this perpetual flow of information. They’ve already found that the flies are selectively blind to visual information that can interfere with their ability to properly performs tasks while dealing with this feat of complex neural computations.
It’s the first illustration of how brains can ignore just one component of a complicated sensory signal carried by an entire group of neurons while leaving other signals in the same group untouched.
This could begin to give us great insight into what information our own brains are and aren’t giving us and how our perception is merely a necessary and self-preserving version of our reality.