Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PSYC323 > somatosensation > Flashcards

somatosensation Flashcards

L8-11, sem 4&5, SQ4-6, reading 4

1
Q

Case Study IW

A
  • rare neurological illness after a flu-like viral infection
  • no sensation of touch below the neck
    • still had pain, heat, but no touch or sense of position
    • appeared drunk, slurred speech
  • autoimmune response attacked nerves
  • had to relearn movement & control using other senses, mostly sight
    • takes immense concentration, attention and imagery
  • socially isolated himself, avoided crowds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

criteria for a sensory system (4)

A
  1. Specialised to receive particular stimulus – i.e. has specific receptors for specific physical energy/chemical molecules
  2. Performs signal transduction (stimulus → neuronal potential)
  3. Relays the neural signal to the brain via certain pathway (synapse 1 → synapse 2 → synapse 3 …)
  4. Has its own cortical region for processing (sensory cortices + association cortices)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Cutaneous “touch” stimuli

A
  • mechanical compression
  • vibration
  • thermal energy transfer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

touch pathway (non-painful cutaneous sensation)

A

lemniscal tract
→ ascending info via peripheral nerve
→ dorsal root
→ lemniscal tract
→ ascend to brain stem and cross midline in medulla
→ medial lemiscus
→ thalamus
→ primary somatosensory cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Pacinian corpuscle

A
  • dynamic pressure, deformation but not vibration
  • low threshold, rapidly adapting, for sudden stimuli
  • e.g. tickle or poke
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Meissner’s corpuscle

A
  • only in glabrous skin (hairless and smooth)
  • shallow, vertical orientation
  • mechanically deformed by light touch
  • very low threshold, shallow position,
    rapidly adapting, respond easily to
    dynamic, moderate stimulation
  • e.g. different textures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Ruffini’s corpuscle

A
  • intermediate depth, horizontal
    orientation (moderate surface area)
  • mechanically deformed by stretch
  • slow response rate (2-3 Hz) allows
    them to respond to stable, low frequency stimulation (e.g. stretch)
  • possible role in non-tactile signalling/proprioception?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Merkel’s disk

A
  • Shallow, moderate surface area
  • Mechanically deformed by pressure
    (but not so easily as PCs)
  • Slow response rate and slowly adapting
  • Respond to static pressure/touch
  • static discrimination of shapes,
    edges
  • E.g. when holding an object
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Reflex arc

A

Sensory neuron (afferent information arrives from skin)
↓
Interneuron (AKA relay neuron)
↓
Motor neuron (efferent information exits out to muscles)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Ramachandran: q-tip demonstration

A
  • single limb amputation
  • feels on cheek and ‘arm’
  • somatosensory cortex plasticity: adjacent areas invade hand area (which is no longer receiving input)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

kinaesthesia vs proprioception

A

= the ability to sense the movement (kinesthesis) and position (proprioception) of our own body
- Arises from inside the body - requires a physical stimulus from the internal environment
- e.g. mechanical stretch/tension in muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Muscle spindles (proprioceptors):

A
  • bunch of 4-8 muscle fibers
  • respond to change in muscle length;
  • high density in hand, neck, ocular muscles;
  • low density in large muscles that generate coarse movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Golgi tendon organs:

A
  • similar to proprioceptors but located in tendon
  • respond to change in muscle tension
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Joint receptor neurons:

A

free nerve endings in joints and respond to joint movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

differentiating factors of nerve fibres

A

Diameter, Conduction Velocity, Myelination State

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

A group fibres (generally)

A

large diameter, high conduction velocity, and are myelinated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

a-alpha fibres

A
  • thickest of A group
  • myelinated, fast conduction
  • for proprioception
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

type of nerve fibre for proprioception

A

a-alpha fibres

19
Q

Posterior Parietal Cortex

A
  • receives info from S1
  • also from visual and auditory cortices, thalamus, hippocampus
  • = association cortex
  • lots of info out as well
20
Q

fibre type with mechnoreceptors

A

A-beta fibres
- Intermediate size (6–12 µm) myelinated, and fast conduction velocity (33–75 m/s)

21
Q

Chemaesthesis (def and receptors)

A

the sensitivity of mucosal surfaces or skin to
environmental chemicals
- involves receptor activation on free nerve endings (Cranial Nerve V)

22
Q

Innervation of Cranial Nerve V

A
  • Via mechanoreceptors
  • Via thermoreceptors
  • Via chemoreceptors
    All on or associated with free nerve endings
23
Q

Chemaesthesis - stimuli + esponse

A

usually classed as irritants/poisons bc activate thermoreceptors and/or nociceptors on free nerve endings
Serves as a safety surveillance system that initiates protective mechanisms: tearing, mucus, salivation, coughing, sneezing, vasodilation/flushing

24
Q

A-delta fibres

A
  • Smallest diameter of the ‘A’ group of fibres (1-6 µm)
  • Partially myelinated, slow conduction velocity (9-11 m/s)
  • Carry noci + thermo signals
25
Q

C-fibres

A
  • Very small diameter (< 1 µm)
  • Unmyelinated
  • Slowest conduction velocity (<1 m/s)
  • Mechano, noci and thermo signals
26
Q

spinothalamic tract

A
  • Thermoreceptors on sensory nerve free endings
  • 1st order (afferent) neuron projects to spinal cord
  • Decussate (cross over) in the spinal cord
  • Synapses with second order neuron, which travels to thalamus
  • Synapses with 3rd order neuron which travels to primary somatosensory cortex (SI)
27
Q

lateral vs anterior spinothalamic tracts

A
  • Lateral spinothalamic tract for thermo, noci
  • Anterior spinothalamic tract for crude mechanoreception
28
Q

Nociceptors

A
  • on free nerve endings
  • A-delta and C fibres
  • lots of different types, including TRP channels (noxious cold or heat)
  • other ones relates to inflammation, low pH, heat, mechanical damage
28
Q

3 Types of Pain:

A
  • abrupt/strong cutaneous sensation, tissue damage
  • damage to neural structures, neural supersensitivity
  • physical pain of psychological origin
29
Q

Pain matrix

A

SI, SII, insula, ACC, PFC

30
Q

Dorsal Lemniscal System - info/function

A
  • touch sensation (good localisation, graduations of stimulus intensity)
  • phasic sensations (vibrations)
  • sensations of movement against skin
  • fine positional and pressure sensations
31
Q

Antlat Spinothalamic System - info/function

A
  • thermal sensation
  • pain sensations
  • crude pressure and touch
  • tickle and itch
  • sexual sensations
32
Q

DL system - receptors

A
  • proprioceptors (muscle spindles, golgi tendon organs, joint receptor neurons)
  • mechanoreceptors in skin (meissner’s, pascinian, ruffini’s, merkel’s)
33
Q

ALST system - receptors

A

nociceptors

34
Q

decussations

A

DL = medulla (2º neuron)
ALST = spinal cord (2º neuron)

35
Q

first synapses

A

DL = dorsal column nuclei in medulla
ALST = spinal cord

36
Q

second synapse

A

DL = contralateral thalamus (ventral posterior thalamic nucleus (VPN))
ALST = thalamus

37
Q

brain projections

A

DL = VPN → primary somatosensory cortex (SI) → secondary somatosensory cortex (SII) of the posterior parietal lobe.
ALST =
* medial thalamus to frontal cortex
* lateral thalamus to SI and SII of somatosensory cortex

38
Q

pain and sensation - spinal cord injuries - ipsi or contra?

A
  • Non-painful info ascends immediately, ipsilaterally
  • Painful info crosses over, then ascends contralaterally
39
Q

McGill Pain Questionnaire

A

used to monitor pain over time and to determine the effectiveness of any intervention
- all sections associated with numbered scale
- section 1: what does your pain feel like?
- section 2: how does your pain change with time?
- section 3: how strong is your pain?

40
Q

motor movement during sleep

A
  • no motor movement during REM sleep
  • The subcoeruleus nucleus (SubC) in the brainstem is activated during REM sleep, and it inhibits the motor neurons (MN) deep in the brainstem
41
Q

REM sleep behaviour disorder

A

⇒ muscle movement during sleep
- normally SubC inhibits MNS
- disordered = abnormalities/insufficient inhibition ⇒ excessive activity of muscles during sleep

42
Q

ACC (ant cingulate cortex) role in pain

A
  • implicated in cognitive pain modulation
  • also in processing pain related emotion
  • receives and processes sensory info
  • also modulatory role: increases sensitivity to sensory inputs

PSYC323 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions