Ant brains are divided into many small bits, known as ganglia. Each ganglia acts like a mini data processor. Each ganglion is responsible for controlling something, like one pair of legs, or one set of wings, or receiving signals from one antenna. Ganglia are also connected to each other.
The brain itself is actually three pairs of ganglia (a total of six) fused together, each acting somewhat independently. One pair controls vision, one pair controlling the antennae, and one pair controlling the mouth. All the ganglia in the brain control only what’s around the brain, near the head and mouth.
In humans, the spinal cord can send signals in two ways: up the spinal cord towards the brain, and from the brain down through the spinal cord. Insects have a one-way highway! Signals only come from the brain, or from one ganglion to the subsequent one. Information is processed only in one direction.
Because the system is broken into so many little bits, they can function on their own. You may have seen headless insects, including ants, still twitching. This is because the ganglia controlling the legs aren’t damaged. The ganglia near the legs also can’t send signals back up to tell the brain that something is wrong!
It may seem weird to us, but it seems to work for ants. There are almost 16,000 ant species around the world, and 5 million insect species!