Somatosenses Flashcards Preview

S2 811 Bio Bases Exam 2 > Somatosenses > Flashcards

Flashcards in Somatosenses Deck (18)
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1
Q

cutaneous sensory info

A
different types of sense receptors, no need to know names of types of receptors
Segregated sensory systems to the brain:
-	pressure
-	vibration
-	temperature
-	pain
2
Q

kinesthesia sensory info

A

(actually in joints)

  • position of limbs
  • strength of movement
  • direction of movement
3
Q

touch

A

Touch is combination of vibration, pressure, and kinesthesia

4
Q

First somatosensory pathway

A

Axons from receptors enter the spinal cord through the dorsal root of spinal nerves

  • some cross immediately, some cross closer to brain, but all somatosensory info is contralaterally mediated
  • to thalamus
  • to primary sensory cortex
5
Q

Second somatosensory pathway

A
2.	Fine touch and kinesthesia
ascend in dorsal columns of spinal cord, ipsilateral side
>	nuclei in medulla, cross to other side
>	ventral posterior nucleus in thalamus
>	primary somatosensory cortex
>	association somatosensory cortex
6
Q

Third somatosensory pathway

A
  1. Pain and temperature, sensory input for reflexes
    Synapse and cross immediately after entering spinal cord
    > ascend in spinothalamic tract of spinal cord
    > ventral posterior thalamus
    > primary somatosensory cortex
    > association somatosensory cortex
7
Q

primary somatosensory cortex

A

post-central gyrus
somatotopically organized
Modules are arranged in columns
- each column responds to a different sub-modality of somato input from a certain area of the body

8
Q

3 perceptual / behavioral effects of pain

A
  • Sensory component (primary somatosensory cortex and assoc area)
  • Immediate emotional response (ACC)
  • Long-term emotional consequences of chronic pain (PFC)
    These three mediated/processed by different brain mechanisms
    Pain is conveyed over separate neural pathways, projects to areas of the brain others do not
9
Q

Sensory aspect of pain

A
  • mediated in primary and secondary somatosensory cortex
10
Q

location of immediate emotional response to pain

A

(in particular aversiveness)

  • mediated in the anterior cingulate cortex (ACC)
  • ACC activated when s’s just heard words denoting pain, also when women saw partners experience pain
  • ACC activation can be lowered with hypnosis, then pain is still felt but less aversion/unpleasantness
11
Q

neural circuits in brain that produce analgesia

A
  • periaqueductal gray receives input from frontal lobes, amygdala, and hypothalamus allowing for learning and emotions to affect responsiveness to pain
  • medulla, too
  • most release endogenous opioids
  • electrical stim of the PAG or medulla produces analgesia (stimulator implants)
12
Q

acupuncture and pain

A

produces endogenous opioid response that is blocked by naloxone

13
Q

hypnosis and pain

A
  • ACC activation can be lowered with hypnosis, then pain is still felt but less aversion/unpleasantness
  • nalaxone does not block analgesia produced by hypnosis
  • hypnosis produces analgesia in ACC rather than periaqueductal gray (PAG)
14
Q

placebo effects

A
  • Analgesia can be induced by placebo
  • increases opioid activity in several areas of brain: dlPFC, ACC, insula, nucleus accumbens
  • Placebo analgesia can be blocked by naloxone so effect occurs at periaqueductal gray
15
Q

fMRI feedback / pain

A

with fMRI feedback, subjects can decrease activity in their ACC which raises their pain tolerance

16
Q

insula

A

secret area of cortex, not visible from outside, lower layer of cortex

  • Stimulation of insular cortex results in painful sensations
  • Painful stimuli activate insula
  • Damage to insula decreases emotional response to pain even though pain is still felt - less distress, less aversive
17
Q

tactile agnosia

A
  • inability to identify objects by touch
  • patient with L parietal lobe damage (somatosensory association area) with intact tactile discrimination (texture, temp, weight, etc) but inability to recognize objects held in her hand
  • bilateral parietal lobe damage with intact tactile discrimination and could draw objects held in his hand but could not identify objects (parallel with associative visual agnosia; breakdown btwn perception and verbalization)
18
Q

pathway of sensory info from head/face

A
  • trigeminal nerve, cranial nerve 5
    > to thalamus
    > to primary sensory cortex