NEU258_Lecture7_Somatosensory_System_Peripheral notes

NEU258_Lecture7_Somatosensory_System_Peripheral notes -...

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Lecture 7 -... Audio recording started: 11:03 AM Thursday, October 04, 2012 Note: Somatosensory/Auditory section of the textbook don’t follow lecture exactly - come to lecture!!!! One of the most studied systems in the body - very well understood in humans due to similarities with that of other organisms. Discriminative Touch Proprioception Temperature (Sense) Nociception Four main chunks (major parts) of the somatosensory system: most surfaces are covered with very fine hair or little hairs (these are not glabrous) Palms, feet, hands, finger pads; many other hairless surfaces - There are many skin receptors on these parts of the body: Nerve endings that stick out Merkel Disk Ruffini Ending Pacinian Corpuscle Meissner's Corpuscle Outer most layer is dead skin cells It has papillary ridges - changes in thickness (swirls and bumps related to skin - clearly visible on the fingertips) Next layer = epidermis (living skin cells) Pushing on the skin causes movement of papillary ridges - mechanical effect Made of modified skin cells Contain stack so these cells Wrapped around these cells is the nerve ending Very sensitive - pressure s on them cause action potentials It produces a rapidly adapting receptor (RA) - See Diagram 2 This system quickly moves to equilibrium Tension causes mechanically means to stress - causes nerve channel to open up and fire action potentials Releasing the stimulus result in a small pulse as well The MC is rapidly adapting Not very good at detecting pressure, but better at detecting change The Meissner Corpuscle (small sacs/nerve endings) Single neurons sample portions of the skin and pass the signals up to the spinal cord The neurons are therefore more sensitive There can be 10-20 corpuscles connected to single neurons Neurons have a large tactile receptive field (a given neurons responds to a relatively large region of skin) Portion of skin - See Diagram 1 Glabrous skin (Hairless skin): Start with the discriminative touch system - different types of skin: Lecture 7 - Somatosensory System (Peripheral) Thursday, October 04, 2012 11:00 AM NEU 258 - Fundamentals of Neuroscience Page 1
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Region of skin when stimulated causes a change in the activity of the neuron/an increase in firing rate in a given neuron
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  • Fall '11
  • Graziano
  • discriminative touch

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