Sensor Phys - K

Question 1

What is the most studied touch R? What type of channels open in response to physical/mechanical stimulus? What do they generate?

Answer 1

Pacinian Corpuscle
Na channels
Generator potential

Question 2

Describe the structure of the Pacinian Corpuscle. How does it respond to physical stimuli? What is adaptation? What happens after stimulus removal?

Answer 2

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

Question 3

What is an afterdischarge? What’s an example?

Answer 3

Persistence of a sensation after stimulus removal

“Phantom” sunglasses

Question 4

What is a sensory unit?

Answer 4

Sensory n and all its branches

Question 5

What’s a receptive field? Are their sizes different?

Answer 5

Area on the skin where stimulation will activate the same sensory unit

Yes, smaller where more sensitive touch is needed

Question 6

What are ways stimuli are coded?

Answer 6

# of APs
Pattern of AP's w/ larger stimuli (doublets and triplets)
# of R's firing (wide stimulus = more receptive fields recruited)

Question 7

How many AP’s can be fired off per second?

Answer 7

~200

Question 8

What’s the least amount of difference between stimuli one can usually detect?

Answer 8

~10%

Question 9

What is the perceived intensity vs actual/measured intensity for muscle senses and cutaneous senses?

Answer 9

Muscle: same

Cutaneous: variable

Question 10

What are the players in presynaptic inhibition? Where is it most likely to happen? What’s the purpose?

Answer 10

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

Question 11

What part of the brain is the gatekeeper of sensory information to the cortex?

Answer 11

Thalamus

Question 12

At which layer in the somatosensory cortex does information arrive to a column via the thalamus?

Answer 12

Layer 4

Question 13

Where is the somatic sensory area 1 (S1)? What is its function?

Answer 13

Post-central gyrus

Determines size, shape, and position; little context

Question 14

Where is S2? What is its function?

Answer 14

Wall of lateral fissure

Cognitive touch, can compare two different tactile sensations, determines whether something should be stored in memory

Question 15

What is stereognosis? What part of the cortex is it associated with?

Answer 15

Being able to identify an object based solely on touch

S2 (somatic sensory area 2)

Question 16

What is a major difference between the human brain vs others?

Answer 16

The amount of cortex associated with “association areas”

Question 17

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?

Answer 17

The parieto-temporal-occipital (PTO) association cortex

S1, S2, and others

Analyzing spatial coordinates and relationships, naming of objects

Question 18

What does plasticity do for stroke patients?

Answer 18

Allows for redirection of affarents to neighboring (remaining) columns at the expense of speceficity

Question 19

What does the law of projection state?

Answer 19

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

Question 20

What does the law of specific nerve energies state?

Answer 20

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)

Question 21

What is plasticity?

Answer 21

The ability for our brain to change in light of new information