How is the sensitivity of a body part related to the sensory cortex?

The relationship between the sensitivity of a body part and the sensory cortex is primarily determined by the size of the area dedicated to that part within the sensory cortex. Each region of the sensory cortex corresponds to a specific body part, and the more sensitive a body part is, the greater the number of neurons representing it. For example, areas such as the fingertips and lips have a larger representation in the sensory cortex due to their heightened sensitivity, compared to less sensitive areas like the back or legs.

This correlation indicates that sensitivity is not uniform across the body; instead, body parts that are more sensitive are allocated a larger portion of the sensory cortex. Thus, the correct choice reflects the direct relationship between the cortical representation size and the sensitivity of various body regions. The correct understanding is that if a larger area of the sensory cortex is dedicated to a specific body part, this corresponds to greater sensitivity in that area.