Question

Which sensory distinction is not encoded by a difference in neuron identity?

(A) white and red

(B) red and green

(C) loud and faint

(D) salty and sweet

Short answer

1. The option “white and red” isfalse.

2. The option “red and green” isfalse.

3. The option “loud and faint” is true.

4. The option “salty and sweet” is false.

Step-by-step solution

Sensory receptors and neuron 

Like other cells, the nervous system cells also follow cell-type diversity. Different cell types in the nervous system are responsible for controlling specific functions.

There are several types of sensory receptors. Each of them perceives different nature of stimuli. Therefore, neuronal identity is important as different neurons become relevant in different settings such as olfaction, touch, and light.

Explanation for option ‘(A)’

White and red denotes colors. There are two types of cells or photoreceptors such as rods and cones. The cones perceive color, while the rods are not sensitive to colors.

Rods detect light and darkness. So, rods can detect white. Signals from the cones for colors are relayed to the brain, which interprets the colors.

Thus, the perception of color is encoded by a difference in neuronal identity.

Therefore, the given statement is false.

Explanation for option ‘(B)’

Red and green are colors perceived by cones. Cones are more sensitive to red than green. The other photoreceptor, called rods, perceive black and white.

Thus, the perception of red and green colors involves neuronal identity.

Therefore, the given statement is false.

Explanation for option ‘(C)’

The intensity of sound, that is, whether it is loud or faint, is encoded by the same neuron or hair cell. In response to sound, the basement membrane in the ear vibrates, causing the hair cells to rise and lower. So, for different intensities of sounds, the frequency at which the hair cell fires differ.

Thus, loud and faint sound intensities are not encoded by a difference in neuronal identity.

Therefore, the given statement is true.

Explanation for option ‘(D)’

Salty and sweet are the taste types. Columnar sensory cells detect taste. Type I glial-like cells, and type II cells detect salty and sweet taste, respectively.

Thus, salty and sweet taste modalities are encoded by a difference in neuronal identity.

Therefore, the given statement is false.