Somatosensation beyond the DC/ML Flashcards
what are 5 primary somatosense modalities
- nociception
- temp
- vibration
- light touch
- proprioception
what are 4 cortical sensory modalities
- graphesthesia
- stereognosis
- 2 point discrim
- double simultaneous stims
what are 3 main classes of receptors and what they respond to
- exteroceptors - light, sounds, tissue damage, temp, touch, pressure
- proprioceptors - monitor muscle, tendons and joints
- enteroceptors - monitor visceral stim
what do chemoreceptor sense
taste and smells
what do mechanoreceptors snese
deformation in cell membrane
what do nociceptors sense
tissue damage in reposnse to mech, thermal, chem damage
what is the receptor threshold
stim intensity needed for AP 50% of the time
what are low and high threshold receptors senses for
low - tactile
high - nociception
what are rapidly adapting receptors
only fire during changes in stim - good for high freq vibration and movement of objects across skin
what are slow adapting receptors
report continuously on the stim - good for pressure, shape
what are nerve fiber classes from largest diameter to smallest
Aa, Ab Ag Ad B C
which are not mylenated
C
what are sensations and location of Aa
limb position, motion - extrafusal muscle cell
what are sensations and location of Ab
skin - conscious proprio, touch, pressure, vibraiton
what are sensations and location of Ag
intrafusal muscle fibers
what are sensations and location of Ad
fast pain, cold, hair follicles
what are sensations and location of B
preganlionic autonomic: white rami
what are sensations and location of C
slow pain, warmth: autonomic post-ganglionic
how is stim intensity coded
frequency of AP
how is locaiton coded
receptor field
how is modality coded
based on the type of axon firing
how is total quality coded
by the population of axons firing
what is adv. to 3 neuron system
can relay to places other than the cortex as well
what are 3 other areas of projection and for what
- to neuron in dorsal horn to supress pain pathway
- to medullary and pontine reticular formations for alter response and modifying reflexes
- to sup. colliculus to drive orienting reflexes
what are 3 integrations that happen at first synapse
- cortical descending inhibition refines attention
- lateral inhibition sharpens localization (review)
- modalities remain segregated
what are Funct. of 4 areas of primary somatosensory area
- responds to input from cut. mechanoreceptors
- responds to input from propriot
3 and 4 - integrate these modalities to diff. shape, size and texture
what is secondary somatosensory area
receives from S1 and thalmus for tactile memory
what is sensory association area
integration of vision and somatosense
