lecture 11 part 2

Question 1

somatosensory cortex organization

Answer 1

ventral posterior complex –> structures –> secondary somatosensory cortex –> to amygdala and hippocampus
low threshold cutaneous receptors for tactile
OR parietal areas –> to motor and premotor cortical
- size and shape of object

Question 2

columns

Answer 2

neurons in the primary somatosensory cortex form distinct columns

Question 3

amputation of digit-

Answer 3

cortex has capacity to rewire - cortical plasticity

in absence of input dendrite needs input so breaks connection and finds a new one

Question 4

repetitive behavioral task

Answer 4

following repetitive behavioural tasks cortical representation will expand functionally

Question 5

dynamic range

Answer 5

range of stimulus intensities over which a receptor neutron can encode changes in intensity as changes in neuronal activity
can be reset by adaptation

Question 6

proprioception receptor type

Answer 6

muscle spindle

afferent axon: large and myelinated b/c require fast feedback loop to let muscles know how hard to contract/relax

Question 7

touch receptor type

Answer 7

merkel, Meissner, pacinian and Ruffini cells

afferent axon: medium and myelinated (1a/II)

Question 8

pain/temp receptor type

Answer 8

free nerve endings

afferent axon: AB, C

Question 9

first and second pain

Answer 9

first pain: sharp, Adelta fiber- myelin

second pain: sustained, dull C fiber - thin and unmyel.

Question 10

vanillin receptor VR-1

Answer 10

activated by moderate heat >45 degrees
natural ligand: endovanilloids produced in response to injury
also activate in response to capsaicin (child oil)

Question 11

anterolateral tract

Answer 11

dorsal root ganglion
crosses over contralaterally
- nociceptive pain

Question 12

antereolateral system

Answer 12

VPN –> somatosensory cortex: where is it, sensory discriminative
amydgala/hypothalamus/PQG: is it unpleasant/ painful?
midline thalamic nuclei- anterior cingulate cortex: affective/motivational (emotion)

Question 13

visceral pain

Answer 13

relayed by interneurons that are also used to relay surface pain information
can end up with pain coming form surface of body if damage to organs
- midline

Question 14

summary pain and temp pathways

Answer 14

body:
contralateral cross over immediately
anterolateral system up to VPLateral nucleus
face:
contralateral cross over immediately up to VPMedial nucleus
trigeminal thalamus tract

Question 15

hyperalgesia

Answer 15

peripheral sensitization - increased sensitivity to pain after injury

Question 16

allodynia

Answer 16

pain induced by normally innocuous stimulus
pain receptors release peptides to dilute blood vessels and leak serum which increase receptor function and swell
aspirin and ibuprofen reduce PG synthesis

Question 17

neuropathic pain

Answer 17

spontaneous or damage resulting from afferent fibers
difficult to treat because no initial peripheral point of pain
can arise following amputation

Question 18

SCN9S- NaV1.7

Answer 18

subtype of sodium channel encoded by SCN9A gene
over responsive: neuropathic pain/ burning
- the hell gene
loss of function: chronic analgesia - insensitive to pain

Question 19

how do opioids releive pain

Answer 19

by acting in the spinal cord or at PAG
- PAG stimulation is analgesic through actions on brainstem nuclei and other transmitters
central and peripheral

Question 20

enkephalin containing neuron

Answer 20

increases dorsal horn projection neutron and inhibits nociceptors
gate out C fibres input