l14

Question 1

pathways of pain and temp + mechano

Answer 1

pain and temp- contralateral

mechano- ipsilateral

Question 2

dermatomes

Answer 2

region innervated by a single pair of spinal or cranial nerves

Question 3

mechanosensory transduction

Answer 3

highly myelinated afferants
- stretch sensitive channels in mebrane
APs generated at nerve ending

Question 4

slowly adapting

Answer 4

continue to fire as long as stimulus is present

- give absolute sense of stimulus and know it is always there

Question 5

rapidly adapting

Answer 5

sense only when stimulus comes on/off

- good for detecting change

Question 6

pacinian copuscle

Answer 6

sense vibrations

• large RF
• rapid adapting

Question 7

ruffini endings

Answer 7

sense skin stretch and proprioception

• large RF
• slowly adapting

Question 8

meissner corpuscle

Answer 8

sense pressure and grip

• small RFs
• rapidly adapting

Question 9

Merkel cell-neurite complex

Answer 9

• sense form and texture of small changes in touch
• small RF
• slowly adapting
• seorotonergic

Question 10

microneurography

Answer 10

tungsten needle electrodes inserted through skin to measure afferants

Question 11

discovery of piezo2

Answer 11

found that mechanically activated currents in merkel cells depend on piezo 2

• knocked out piezo and found no currents
• expressed gene in different cell types

Question 12

Atoh knockout–>

Answer 12

conditionlal knockout that doesnt have merkel and piezo - shows intermediately adapting responses
therefore merkel cells are repsonsible for encoding sustained phase

Question 13

channel rhodopsin - merkel cells

Answer 13

expressed Chr in merkel cells to directly activate using light and found that by activating merkel cell its enough to create activity in neuron
- must be releasing some chemical (serotonin) to drive response

Question 14

how did they test merkel cells endogenous role

Answer 14

silenced it to see endogenous activity
Achr activates chloride pumps to depolarize which blocks activity
- see loss of activity for period
therefore merkel cells play essential role in mediating touch info

Question 15

piezo in touch

Answer 15

most important for increasing sensitivity - amplify responses at low levels

Question 16

medial lemniscal pathway

Answer 16

touch:
cuneate tract- upper body
gracile tract- lower body

Question 17

trigeminal lemniscal pathway

Answer 17

information from head

- trigeminal ganglion

Question 18

density of receptors

Answer 18

non-uniform

- density of receptors correlates to spatial resolution

Question 19

columns

Answer 19

neurons in S1 form funcitonally distinct columns

- within a didgit you can see organization in columns and map

Question 20

lateral inhibition

Answer 20

increases acuity

- silence neurons beside it to get specific response

Question 21

convergence

Answer 21

decreases acuitiy

Question 22

orientation selective neuronsqneurons that respond to exact orientation of stimulus
- cares for specific shape

Answer 22

direction selective neurons
how things move with respect to your hand
ex grip

Question 23

how is direction selectivity acheived

Answer 23

offset inhibition/excitation field

• excitation before inhibition causes spiking
• inhbition before excitation causes no response