Merkel's discs are known for detecting which characteristic of touch?

• A. Deep vibrations
• B. Light touch changes
• C. Light touch intensity
• D. Fine spatial details and texture under steady pressure

Answer: (D)

The key idea is how tactile acuity and texture discrimination are achieved by specific skin receptors that respond to sustained contact with fine spatial detail. Merkel discs are slowly adapting (SA1) mechanoreceptors located at the epidermal-dermal junction with small receptive fields. Because they fire continuously as long as pressure is maintained and their receptive fields are small, they provide high spatial resolution, allowing you to detect fine details and textures on a surface even under steady indentation. This makes them especially important for tasks like reading Braille or feeling the texture and edges of objects when you press against them. In contrast, other receptors are either rapidly adapting (responding best to changes or movement, not sustained texture) or tuned to different stimuli (vibration, stretch), so they don’t convey the same level of fine texture detail during steady pressure.