Question

A virus has been sweeping through southern Arizona, causing neurological symptoms of numbness. You know that blood Na⁺, K⁺ and Ca⁺⁺ levels are normal (140, 5, 9 mequivalents per liter, respectively).

You are researchers focused on understanding how the virus is affecting neurons. You have been able to infect rats with the virus, and they also appear to experience numbness, as indicated by their lack of response to touch.

First, how could you test whether the virus was affecting just touch receptors, vs. more generalized parts of the brain, say the ascending tracts that carry the touch information, or the brain?

Second, you are able to create an in vitro preparation of the sensory neuron/touch receptors for the rat. Describe experiments that would test the hypothesis that the virus is blocking either Na⁺ or K⁺ channels in the sensory neuron.

Answer 1

To test if the virus is affecting touch neurons or not, we need to test the sensory neurons innervating skin. For the identification of ascending tracts, we need to test motor neurons reaching to brain.

to test the hypothesis, the virus is blocking either Na⁺ or K⁺ ions channel. We need to test the ion concentration at extracellular fluid after incorporation of activation potential. Also, it can be tested using the voltage clamp experiment.