June 12, 2009

Seeing zigzags

You can literally see how your brain works during a migraine with aura and learn first hand about cortical organization

In the article that starts with the question "Does the migraine aura reflect cortical organization?", published in the European Journal of Neuroscience, I considered the old idea that flickering zigzag patterns seen during migraine with aura reflect properties of our neurons. Let me explain this briefly.

It is well known that neurons fire much more frequently if the condition they are tuned for is met. For example, one of your neurons may only fire if you see a vertical line at a specific location in your visual field. We know very well how such neurons are organized on the surface of your brain. This is called cortical organization. In general, this concept denotes how sensory conditions that must be met for neurons to fire—such as edge orientation, but also color or any other feature of the outside world—are spatially organized on the surface of your brain. Sometimes, this is also called a cortical feature map.

It seems natural to suggest that hallucinatory zigzag patterns seen during migraine with visual aura reflect the organization in the visual cortex representing the feature edge orientation. What other than a pattern of edges is a zigzag? That migraine aura reflects cortical organization was proposed by many scientists, but how to prove or at least support this hypothesis?

My idea was to translate our current knowledge of both cortical organization and migraine pathophysiology into a neural network model. I should then be able to reconstruct the flickering zigzag patterns seen during migraine in a computer simulation. The result is displayed on the right. In fact, the actual computer simulation is animated, but I chose a still image. Otherwise this blog would become unreadable for those who suffer from migraine. Flickering patterns can trigger migraine. For an animated version, please see my scholarpedia article Models of cortical spreading depression. We now have sample movies that can be compared with the zigzags seen during migraine, like we measure tinnitus by sample noise.

1 comment:

  1. I noticed you had begun following my Twitter feed, probably because I tweeted about experiencing a migraine aura. Interesting blog post; I've also had a look at the scholarpedia article.