Lecture 20- Somatosensory System Flashcards
Which sensory receptors are found deeper in the skin and tend to respond to vibration?
pacinian corpuscles
Which sensory receptors are found superficially in the dermis and respond to light touch?
Meissner’s corpuscles
Name 3 types of receptors found in the skin.
free nerve endings
pacinian corpuscles
meissner’s corpuscles
What type of sensation do meissner’s corpscles respond to?
light touch
How is modality of a stimulus “coded”?
the type of sensory receptor that is stimulated
How is a particular stimulus localized?
sensory fibers have specific receptive fields
How is the intensity of a stimulus coded?
- the frequency of firing
2. number of activated fibers
Is the size of the receptive field the same for all nerve fibers?
no the size of the receptive field varies depending on the area of the body ie. smaller receptive field on the finger tip versus the arm
What type of fibers are found in the anterolateral system?
small myelinated or unmyelinated A-delta and C fibers (slower)
What types of fibers are found in the Dorsal Column/Medial Lemniscus system?
Larger, faster, A-Beta Fibers
What is found in Brodman’s areas 3,2,1?
Primary somatosensory cortex (postcentral gyrus of the parietal lobe)
What would be expected to happen to the stimulus information due to convergence and divergence?
expected that they would cause a loss of accurate stimulus localization (“blurring”) of the signal
This does NOT occur thanks to LATERAL INHIBITION
What is the result of lateral inhibition?
a fine tuning and sharpening of sensory signals as you ascend
What occurs if lateral inhibition is removed?
seizures
What is stereognosis?
the ability to perceive form through touch
