Neuroplasticity in Response to Stress and Injury

Question 1

What is cortical expansion/extension defined as?

Answer 1

The reorganization of brain structures as a response to sensory loss; cortical maps devoted to a particular function may enlarge or reformat with frequent exposure to a stimulus (i.e., music and A1) or injury (amputation).

Question 2

What is phantom limb pain?

Answer 2

Defined as a pain sensation to a limb, organ, or other tissue after amputation
and/or nerve injury. (the phantom limb can also exist without pain)

Question 3

What makes PLP complex to understand and define? (4 reasons)

Answer 3

Hard to distinguish from post-operative pain(1); complex phenomenology(2); depends on what limb is amputated(3) and at what age as well(4).

(Existence of pain without a sensory input)

Question 4

What are two explanations for cortical remapping in response to amputation?

Answer 4

Gradual exp. = sprouting of axonal collaterals into neighboring regions “hungry” for input. (cheek area axons sprout into the amputated hand region)

Rapid exp. = redundant, non-functional connections are made active (reserve troops in S1)

Question 5

How does the pain potentially manifest in PLP?

Answer 5

The dissonance between motor and sensory areas (that create our body image) is paired with a loss of inhibitory control on the dorsal horn in the spinal cord.

The loss of inhibitory control in the dorsal horn makes innocuous, normal sensations feel painful. Overall, we see dysfunction in the pain modulation from the somatosensory cortex and periaqueductal gray.

Question 6

What does mirror therapy hope to accomplish in PLP patients?

Answer 6

Mimic the amputated, non-functional limb, with the existing functional limb. This process is thought to repair the body image and subsequent pain.

Question 7

VR therapy and PLP

Answer 7

Can provide a sensory experience (like mirror therapy) for patients whose body image is damaged by errors in cortical remapping.

Question 8

What does the neuromatrix theory of pain assert?

Answer 8

Pain is a subjective experience produced by patterns of neural impulses (widespread network across the brain).

The widespread network creates our body-self image, and if there are errors in the pattern generation (i.e., poor remapping due to amputation) – we have abnormal experiences.

Question 9

What are 4 ways we can classify neuroplasticity?

Answer 9

homologous area adaptation, cross-modal reassignment, map extension, and compensatory masquerade.