Question

Distinguish between the posterior column-medial lemniscus pathway and the anterolateral pathway in terms of the types of sensory information each conveys. Explain why touch sensation is not eliminated by a lesion in either pathway.

a) Posterior column-medial lemniscus conveys fine touch and proprioception; anterolateral conveys pain and temperature. Touch sensation is not eliminated because of bilateral representation.
b) Posterior column-medial lemniscus conveys pain and temperature; anterolateral conveys fine touch and proprioception. Touch sensation is not eliminated because of collateral pathways.
c) Both pathways convey the same types of sensory information. Touch sensation is not eliminated because of redundant circuits.
d) Neither pathway is involved in touch sensation; touch sensation is eliminated by lesions in both pathways.

Answer 1

The posterior column-medial lemniscus pathway conveys fine touch and proprioception, while the anterolateral pathway transmits pain and temperature. Touch sensation persists despite lesions in either pathway due to bilateral representation of sensory information in the brain.

Step-by-step explanation:

The posterior column-medial lemniscus pathway and the anterolateral (spinothalamic) pathway convey different types of sensory information. The posterior column-medial lemniscus pathway is responsible for transmitting fine touch, vibration, and proprioception, while the anterolateral pathway carries pain and temperature sensations. Touch sensation is not eliminated by a lesion in either pathway because of bilateral representation; the brain receives sensory information from both sides of the body which allows continued perception of touch, even if one pathway is compromised.

The correct answer to the question posed would therefore be option a) Posterior column-medial lemniscus conveys fine touch and proprioception; anterolateral conveys pain and temperature. Touch sensation is not eliminated because of bilateral representation.