Epilepsy may result in motor seizures due to massive synchronous firing of neurons in a small area of the cerebral cortex (epileptic focus). Excitation spreads from the focus, involving an increasingly larger area of the cortex. A drug for the treatment of epilepsy would be most effective if it caused which of the following changes in the epileptic focus? A. an increase in the neuron-firing thresholdB. An increase in extracellular Na + concentrationC. a decrease in axon-membrane permeability to negative ionsD. a decrease in the length of the depolarization stage

Answer: Option A

Explanation:

Epilepsy can be defined as the medical condition in which the central nervous system disorder in which the brain activity becomes abnormal which results in the abnormal behavior, sensation accompanied by loss of awareness.

In this condition a drug that can best treat epilepsy should reduce the activity of neurons in the epileptic focus which are excitatory neurons based on the effect throughout their cortex.

It does so by increasing the threshold which is required to generate action potential which will decrease the chances that neurons will fire.

This effect will reduce the overall amount of excitation which spreads from epileptic focus throughout the cortex.

hence, the correct answer is option A