Which statement best differentiates sensory adaptation from receptor desensitization?

Which statement best differentiates sensory adaptation from receptor desensitization?

• A. Desensitization is a temporary increase in receptor sensitivity.
• B. Adaptation is a reduced response to a constant stimulus; desensitization is a receptor-level decrease in responsiveness.
• C. Adaptation occurs only in olfaction.
• D. Desensitization occurs after adaptation and is not related to receptors.

Answer: (B)

Sensory adaptation means the system’s output decreases when a stimulus remains constant for a while, reflecting a change in how the nervous system processes or encodes ongoing input. This is a broad, system-level phenomenon that can involve both peripheral and central adjustments, so you end up perceiving the stimulus as less intense even though it’s still present. Receptor desensitization, on the other hand, is a change at the receptor itself. After prolonged exposure to a stimulus, the receptor becomes less responsive to further stimulation due to processes like receptor phosphorylation, arrestin binding, and sometimes receptor internalization. This directly reduces the receptor’s ability to activate downstream signaling, independent of higher-level processing. So, the best distinction is that adaptation describes a reduced response to a constant stimulus overall, while desensitization refers to a receptor-level decrease in responsiveness. The other statements don’t fit because desensitization is not a temporary increase in sensitivity, adaptation isn’t limited to olfaction, and desensitization does involve receptor-level changes.

Sensory adaptation means the system’s output decreases when a stimulus remains constant for a while, reflecting a change in how the nervous system processes or encodes ongoing input. This is a broad, system-level phenomenon that can involve both peripheral and central adjustments, so you end up perceiving the stimulus as less intense even though it’s still present.

Receptor desensitization, on the other hand, is a change at the receptor itself. After prolonged exposure to a stimulus, the receptor becomes less responsive to further stimulation due to processes like receptor phosphorylation, arrestin binding, and sometimes receptor internalization. This directly reduces the receptor’s ability to activate downstream signaling, independent of higher-level processing.

So, the best distinction is that adaptation describes a reduced response to a constant stimulus overall, while desensitization refers to a receptor-level decrease in responsiveness. The other statements don’t fit because desensitization is not a temporary increase in sensitivity, adaptation isn’t limited to olfaction, and desensitization does involve receptor-level changes.