Generally, how do sensory neurons encode stimulus intensity? What is the dynamic range of a sensory neuron? How does range fractionation improve the dynamic range?

Question

What will be an ideal response?

Answer 1

Answer: Sensory neurons change their firing rates to encode stimulus intensity. A higher intensity stimulus generally results in a higher frequency of firing, while a lower-intensity stimulus results in a lower frequency of firing. The dynamic range of a neuron is the range between the minimum and maximum signals that can be discriminated. At some point, the intensity of the stimulus will be so low in magnitude that the sensory neuron will not fire reliably. The "threshold of detection" is defined as the weakest stimulus that produces a response in a receptor 50% of the time, and it forms the lowest limit of the neuron's dynamic range. At the top of the dynamic range, the neuron has reached its highest firing frequency, and cannot increase any more regardless of an increase in stimulus intensity. This saturation point forms the highest limit of the cell's dynamic range. Range fractionation happens when different sensory cells are sensitive to different (but overlapping) portions of the dynamic range. Using a strategy in which groups of sensory neurons work together within a single sensory organ, this effectively allows the organ to code for a much wider range of stimulus intensities.