Introduction to Sensory Systems Flashcards
sensory coding
the nervous system must convert information about the environment into its own language of graded and action potentials
Stimulus Type (modality)
coded by which receptors are activated by a given stimulus
modalities =
different sensations
examples of modalities
seeing, smell, taste, hearing, touch, pressure, pain, stretch, temperature, balance, joint position, body motion, body position
stimulus location
detected via each sensory organs types of receptive fields
receptive fields=
areas of the body defined by the presence of sensory receptors
stimulus duration
coded via two types of receptors
non-adapting sensory receptors
rapidly adapting sensory receptors
non-adapting sensory receptors
maintain activity as long as stimulus is applied
duration of stimulus is proportional to the duration of action potentials entering the CNS for non-adapting receptors
rapidly adapting sensory receptors
activated only at the onset and cessation of a stimulus
code changes the stimulus
stimulus intensity
how much of a stimulus is present in the receptive field
intensity of a stimulus depends on
the strength of the stimulus present
lowest detectable intensity =
sensory threshold
not fixed, can be increased/decreased by practice, fatigue, context and attention (changes occur in the brain NOT at the receptors)
why does the CNS code or extract intensity information
distinguish between stimuli that only differ in intensity
evaluate a stimulus over a range of intensities
frequency coding
stronger stimuli evoke a larger receptor potential which cause a greater number and higher frequency of action potentials
- increased intensity coded = increased frequency of action potentials entering the CNS from receptor
- stronger the stimulus = greater the number of action
recruitment
increased stimulus intensity activates surrounding receptors
