Joseph is a 59-year-old construction worker who recently suffered a stroke. A small blood clot became lodged in one of the vessels serving the right side of his brain and restricted blood flow to a portion of his right precentral gyrus. Many neurons in that area were damaged or destroyed and, as a result, Joseph is partially paralyzed on the left side of his body. He is able to move his left leg and walk, and can also move his left arm, but his left hand and the left side of his face are paralyzed.

Answer the following problems about the case study:

Why were Joseph's left face and hand paralyzed, but not the rest of his arm or his leg?

What is preventing Joseph from moving his left hand? In your answer, include the following:

First, describe normal function of a motor neuron that forms a synapse with a muscle cell. How is the signal that initiates movement transmitted from the neuron to the muscle? Describe this process in detail.

Next, keeping in mind that the motor neuron itself is not damaged, describe how damage or destruction of a neuron that communicates with the motor neuron prevents Joseph from moving his hand.

With time, and perhaps some physical therapy, Joseph may recover some of the movement in his left hand and face. What factors might contribute to this recovery? In your answer, include the following:

Why can't Joseph's brain simply replace those neurons that were damaged and destroyed by the stroke?

How might compensation allow Joseph to regain some of his lost movement?

Describe at least one experimental treatment that might improve movement in Joseph's case, and describe how this treatment would impact Joseph's nervous system.