The surface area of the brain’s sensory cortex corresponding to the hand is larger than the area corresponding to the upper arm because the skin on the hand

Question

BlackTom AI · Accepted Answer

The question asks why the brain’s sensory cortex area devoted to the hand is larger than that for the upper arm. 
Option 1: 'has greater acuity.' This is the key concept: the hand has finer discrimination (higher tactile acuity) because more cortical real estate is dedicated to processing its sensory inputs, reflecting a smaller receptive field and more precise spatial mapping. 
Option 2: 'has greater sensitivity.' While the hand is sensitive, greater sensitivity is not the primary explanation for the larger cortical area; sensitivity is a related concept, but acuity specifically refers to discrimination ability, which motivates cortical magnification.
Option 3: 'has a greater surface area.' The question concerns cortical representation, not the skin’s surface area itself. Even if the hand’s skin is larger or smaller, the cortical area expansion is best explained by functional demands (acuity) rather than skin size per se. 
Option 4: 'has greater sensory convergence.' Higher convergence (more inputs combining onto a neuron) would typically reduce acuity, not explain an enlarged cortical area for the hand. In fact, the hand has less convergence to preserve fine details, which supports higher acuity rather than reduced mapping.
Overall, the strongest and most direct justification is that the hand’s higher tactile acuity drives a larger cortical representation, making Option 1 the correct choice. The other options either describe related notions inaccurately or misattribute the cause of cortical magnification.

The surface area of the brain’s sensory cortex corresponding to the hand is larger than the area corresponding to the upper arm because the skin on the hand单项选择题

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