Lecture 9 Review

Question 1

What are properties of sound waves?

Answer 1

pitch = frequency
amplitude = loudness
sound waves = compressions in air due to vibrations`

Question 2

What is the function of the outer ear?

Answer 2

To focus sound waves and helps localize sounds

Question 3

What is the function of the middle ear?

Answer 3

Transfer air compressions to fluid compressions. amplifies the force of the wave

Question 4

Describe the transduction of auditory stimuli

Answer 4

Sound waves move tympanic membrane - moves ossicles - moves membrane at the oval window - moves the fluid in cochlea - response in sensory neurons

Question 5

What is the tonotopic organization of the cochlea?

Answer 5

The point of resonance depends on the frequency of the wave
low freq - makes it to the thick and flexible apex
high frew - stays near the base which is thin and stiff

Question 6

Describe the structure of the inner ear

Answer 6

The organ of Corti lies between the basilar (flexible) and tectorial (rigid) membranes. This is where transduction occurs. The waves of the basilar membrane are connected to and move the cilia of the tectorial membrane.

Question 7

Describe the depolarization of the hair cells in the auditory system

Answer 7

movement of basilar membrane changes conformation of cilia, increases K conductance = depolarization = opening of vg-Ca channels = increases transmitter release
Endolymph has high [K]
NOT CONSIDERED A NEURON
Graded receptor potential

Question 8

What is frequency tuning?

Answer 8

Neurons respond maximally to characteristic frequencies, similar to population encoding

Question 9

What is the vestibular system?

Answer 9

it helps us orient our head versus gravity. Head movement activates hair cells in the system. Similar to auditory system, but uses orientation of body relative to gravity.

Question 10

Describe the mechanosensitive ion channels of the somatosensory system.

Answer 10

Open in response to mechanical stimuli, cause conformation changes in the proteins to open pore and generate ionic current, leading to depolarization

Question 11

What causes different sensitivity regionally?

Answer 11

variation in receptor type and amounts

Question 12

What are the pain cells?

Answer 12

free nerve endings. they receive chemical and mechanical transduction

Question 13

What are thermoreceptors?

Answer 13

cells that are sensitive to changes in temperature, not absolute temperature

Question 14

How are afferent fibers in the somatosensory system different?

Answer 14

Touch fibers are fast and myelinated
Pain fibers are slow - smaller and/or lack myelin
initial and prolonged pain are mediated by different fibers

Question 15

Where does somatosensory information enter the spinal cord?

Answer 15

all comes together through the dorsal horn

Question 16

What is a dermatome?

Answer 16

the area of the body innervate by the left and right dorsal roots of a given segment of a spinal cord. 1:1 ratio. afferents enter spinal cord in between vertebrae

Question 17

What are dorsal root ganglion fibers comprised of?

Answer 17

Skin and visceral fibers

Question 18

How does touch information travel up the spinal cord?

Answer 18

it travels up the dorsal columns ipsilaterally

Question 19

How does pain information travel up the spinal cord?

Answer 19

it travels up the lateral column or spinothalamic tract

Question 20

describe the touch pathway

Answer 20

goes up the dorsal column, relays at medulla, synapse at brainstem, projects to the VPL of the thalamus and then primary somatosensory cortex

Question 21

Describe the pathway for facial touch

Answer 21

receptors of the face form the trigeminal nerve, synapse on trigemenal nucleus of the pons, then to VPL thalamus then to cortex

Question 22

Describe the pathway for temperature and pain

Answer 22

relayes at spinal leves, travels to VPL, then primary cortex. spinothalamic tract
touch and pain paths interact at spinal level to gate pain information

Question 23

Where is the primary somatosensory cortex and how is it organized?

Answer 23

Postcentral gyrus
area of the cortex is proportional to sensitivity of the body region
inputs from different types of receptors are in parallel pathways and in cortical columns

Question 24

Explain the plasticity in somatosensory maps

Answer 24

loss of input can alter the somatosensory mapping in the cortex

Question 25

Describe conscious perception

Answer 25

awareness beyond detection of stimuli

pay attention to certain aspects = filter

Question 26

Describe attention and its relationship with afferent pathways.

Answer 26

There seems to be an efferent modulation of afferent pathways = mediates attention.