Neurotopia

So, you might ask, why do an experiment in crawdads? Well, what the authors were studying here was the effects of carbon dioxide on paralysis. And though vertebrates (like us), and invertebrates (like crayfish) are very different, the effect of carbon dioxide is universal. If you increase the carbon dioxide the animal is exposed to, they will become paralyzed and pass out. The question is, why and how does this happen?

The basic mechanism is already known: when there's high carbon dioxide present in the body, it will combine with water into two other chemicals, bicarbonate and protons. Bicarbonate is basic and can increase the body's pH, but protons decrease pH. And if pH decreases far enough, the animal in question will pass out.

But the question is, how is this happening? What receptors and areas of the central nervous system are producing the effect? To examine this, the scientists looked in crayfish, and looked at various neurotransmitters, in particular, the neurotransmitter glutamate. They found that the presence of carbon dioxide in crayfish inhibits glutamate responses in the central nervous system, blocking chemical neurotransmission, but NOT blocking the electrical impulses going down the neurons. They monitored all of this by monitoring glutamate transmission, and also monitoring the heart rate and ventilation of the crayfish. This allowed the authors to look at whether or not the crayfish had passed out or was paralyzed by carbon dioxide, basic on the responses from the crayfish when you lightly tap on its tail. They could correlate these measures with the recordings they were also doing from neurons, to see how changes in neurotransmission correlated with the behavioral responses of the crayfish.

You might think, this is really pretty basic, and it is. But it's also potentially very important, for humans and animals under conditions of high carbon dioxide, and could allow us to develop therapies to help under these conditions. And further understanding of this mechanism could also enable us to investigate how animals might differ when they are adapted to conditions of low pH.

And the coolest thing? They did this whole study in crayfish, with wires. And they made a VIDEO! Check it out as Sonya Bierbower shows you how to monitor heart rate and ventilation in crayfish, in a complete methods paper presented online! It's a super cool new way to do things, and I highly recommend you check it out!