Imagine this: You are at work when you start to feel numbness, and then a tingling sensation on your lips and tongue on the left side of your mouth. Maybe it spreads to your cheek and then your arm on the same side, making it feel heavy. When you pick up a book to read, you find that you have to re-read the same sentence several times. You notice you can’t really see out of your left eye. Suddenly, a band of light appears just beneath your point of focus. The band has every color of the rainbow, and spins, flashes, and flutters around. The bar stays in the same spot no matter where you look. Then, your peripheral vision goes missing.
A few minutes later, your vision improves and is almost back to normal. Then, the pain hits. It begins as a dull throb in the back of the head, then escalates quickly to an intense pain deep in the left side of the head. As the pain worsens, your vision returns back to normal.
Has this ever happened to you? This is a typical aura experience.
Because auras are not well understood, many migraineurs do not know when they are experiencing an aura. Auras can come with or without pain, and manifest in a wide variety of ways. Yet, the commonly known definition of auras is very narrow. They are generally only described as a colorful aura similar to the Northern Lights, or an aura that looks like a curved chainsaw.
In truth, auras take a multitude of shapes and forms.
What is an aura?
Auras represent a flow of special electrical current across the brain, called cortical spreading depression (CSD). CSD spreads about 1 millimeter per minute, meaning the current travels across the whole brain in about 30 minutes.
The aura or pattern you see is caused by each neuron as the special electrical current touches it. This wave of electricity traveling from one region of the brain to the other is how an aura becomes visible to you.
The occipital lobe is the visual processing center—it is the part of the brain that creates patterns from the information your eyes sense. When you see patterns or flashes of light during an aura, your occipital lobe recognizes the electricity, but it is unable to differentiate if this is something you are seeing with your eyes or if this is something happening in the visual region of your brain. The electrical current passing from one neuron to the other appears to you as an aura point, which can be a flash, a spot, or part of a larger whole aura.
On the other hand, the dark or blind spots you see prior to an aura (or maybe you have no aura at all) correspond to regions of the brain that have no electricity to function. The cells in this region have some closed ionic channels and cannot pass on any electricity. In fact, this unbalanced voltage of cells is what triggers a migraine. Read more about electrical imbalances and migraine causation here.
Why the slow flashes and colors? Electricity sent by a neuron can travel only one millimeter per minute!
Auras Come in All Shapes and Forms
Here we'll go over some often-unknown forms of auras that migraineurs experience. Now you can find out if you have been having auras without even knowing it!
Have you experienced auras like these or something totally different from what we described here? Let us know in the comments!