Question

A virus has been 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.

1. 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?

2. 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.

Hint: Compare the electrophysiological responses of the somatic sensory cells of virus-infected and not- infected rats. Assume that, in response to touch, healthy touch receptor cells exhibit depolarizing graded potentials and then increase action potential frequency.

Answer 1

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