Sensor Phys - K Flashcards
What is the most studied touch R? What type of channels open in response to physical/mechanical stimulus? What do they generate?
Pacinian Corpuscle
Na channels
Generator potential
Describe the structure of the Pacinian Corpuscle. How does it respond to physical stimuli? What is adaptation? What happens after stimulus removal?
Alternating layers of membrane w/ fluid between, these surround the n ending
Layers deform when touched leading to Na channel opening and an AP
Adaptation occurs when membranes and fluid of the Pacinian Corpuscle rearrange around the stimulus
Rebound, membranes and fluid move again causing more AP’s
What is an afterdischarge? What’s an example?
Persistence of a sensation after stimulus removal
“Phantom” sunglasses
What is a sensory unit?
Sensory n and all its branches
What’s a receptive field? Are their sizes different?
Area on the skin where stimulation will activate the same sensory unit
Yes, smaller where more sensitive touch is needed
What are ways stimuli are coded?
# of APs Pattern of AP's w/ larger stimuli (doublets and triplets) # of R's firing (wide stimulus = more receptive fields recruited)
How many AP’s can be fired off per second?
~200
What’s the least amount of difference between stimuli one can usually detect?
~10%
What is the perceived intensity vs actual/measured intensity for muscle senses and cutaneous senses?
Muscle: same
Cutaneous: variable
What are the players in presynaptic inhibition? Where is it most likely to happen? What’s the purpose?
Axo-axonal synapse
Inh pre-synaptic terminal releases GABA which causes Cl channel opening and hyperpolarization
3 neurons, A and C compete for B
Most likely to happen between neighboring R’s at the first synapse in their pathway
To increase the brain’s ability to localize signals
What part of the brain is the gatekeeper of sensory information to the cortex?
Thalamus
At which layer in the somatosensory cortex does information arrive to a column via the thalamus?
Layer 4
Where is the somatic sensory area 1 (S1)? What is its function?
Post-central gyrus
Determines size, shape, and position; little context
Where is S2? What is its function?
Wall of lateral fissure
Cognitive touch, can compare two different tactile sensations, determines whether something should be stored in memory
What is stereognosis? What part of the cortex is it associated with?
Being able to identify an object based solely on touch
S2 (somatic sensory area 2)
What is a major difference between the human brain vs others?
The amount of cortex associated with “association areas”
What part of the cortex is associated with high-level interpretation of sensory input? Where does it receive from? What are some examples of its job?
The parieto-temporal-occipital (PTO) association cortex
S1, S2, and others
Analyzing spatial coordinates and relationships, naming of objects
What does plasticity do for stroke patients?
Allows for redirection of affarents to neighboring (remaining) columns at the expense of speceficity
What does the law of projection state?
Deals with where you feel it, no matter where along a path we stimulate.. The perceived sensation is always referred back to the area of the body in which its R is located
What does the law of specific nerve energies state?
Stimulation of a sensory pathway at any of its points leads to the perception of a sensation that is dictated by the nature of the R that would normally activate that pathway (temp, pain)
What is plasticity?
The ability for our brain to change in light of new information
