Final answer:
The pruritic threshold refers to the minimum stimulus necessary to cause itching and can result from the summation of graded potentials in sensory neurons, either spatially or temporally, until the action potential threshold is reached.
Step-by-step explanation:
The pruritic threshold refers to the minimum amount of a stimulus that causes itching and can lead to the scratching behavior. While the term is not explicitly discussed within the provided references, we can infer that it relates to the concept of an absolute threshold in sensory systems, where threshold refers to the minimum amount of stimulus energy necessary to be detected. In neural processing, this threshold can be reached through summation, the process by which graded potentials, either depolarizations or hyperpolarizations, add together. This summation allows a neuron to reach the action potential threshold, which in the context of itching, would mean the sensory neurons have been activated sufficiently to send signals to the brain that result in the sensation of itch.