Final answer:
The perception threshold corresponds to the minimum intensity of stimulus necessary to generate an action potential, leading to its perception in the CNS. Receptor potentials vary with stimulus strength and, upon reaching a threshold, result in action potentials that are central to the perception process.
Step-by-step explanation:
The perception threshold describes the intensity of stimulus required to generate a perceptual response in the sensory system. This occurs when a stimulus is strong enough to change the cell membrane potential of a sensory neuron to a degree that reaches a threshold, ultimately triggering an action potential, which is then relayed into the central nervous system (CNS). The sensory information is encoded in terms of stimulus type, location, duration, and intensity, and it is this transmission of action potentials that leads to the perception of the stimulus at higher levels in the CNS.
Receptor potentials are the initial change in electrical potential produced by the encounter between a sensory receptor and a stimulus. Should the strength of the receptor potential surpass the threshold, an action potential is fired. The magnitude of these receptor potentials varies with the strength of the stimulus, which can either depolarize the neuron or, in certain sensory systems like vision, produce other types of response.
When it comes to detecting the presence of a stimulus, the term absolute threshold is used to refer to the minimum amount of stimulus energy required to be detected 50% of the time. Perception of a stimulus, therefore, is not solely the activation at the sensory receptor level but also involves higher cognitive processing within the brain.