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Motor Control > Sensory coding > Flashcards

Sensory coding Flashcards

1
Q

Sensory cells (2)

A

specialized cells that change their properties in response to stimuli
convey info to the CNS regarding sensation/stimulus

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2
Q

sensory transduction

A

transformation of physical energy into electrical and/or chemical energy - establishes common language throughout CNS

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3
Q

How are biological sensory receptors classified? 1-3

A

based on the origin of the stimulation to which they primarily respond

  • exteroceptors: stimuli in external environemnt
  • interoceptors: stimuli within the body
  • proprioceptors: mechanical stimuli associated with configuration and movement of body and body segments
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4
Q

photoreceptors

A

light

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5
Q

mechanoreceptors

A

mechanical energy - vestribular and touch receptors

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6
Q

chemoreceptors

A

chemical substances (taste and smell receptors)

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7
Q

thermorceptors

A

thermal energy

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8
Q

noci(o)receptors

A

intense energy of uniform or combined states

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9
Q

5 modalities of receptors?

A 
vision
hearing
touch 
taste 
smell
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10
Q

submodalities of vision - 2

A

colour/movement

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11
Q

submodalities of hearing - 2

A

high/low frequency

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12
Q

submodalities of touch

A

-

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13
Q

submodalities of pain -2

A

dull ache/stabbing pain

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14
Q

submodalities of temp -2

A

hot/cold

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15
Q

proprioception vs kinesthesia

A

static position vs dynamic movement - awareness of the position and movement of segments of our body in space and in relation to one another

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16
Q

four pieces of info conveyed with a sensation

A

modality
intensity
duration
location

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17
Q

Definition of sensory modality

A

Type of information (vision/hearing etc)

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18
Q

Sensory modality is coded in what two ways?

A

Receptor sensitivity: receptors sensitive to specific energy forms - sometimes stimulus can stimulate one or more receptors to work simultaneously.
Labelled lines: axons of receptors function as modality specific lines of communication between periphery and CNS

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19
Q

Stimulus intensity

A

The amount of stimulus

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20
Q

What’s stimulus intensity coded by?

A

AP discharge frequency

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21
Q

Stimulus intensity clinical application

  • threshold for stimulation
  • sensory threshold
A

Lowest stimulation intensity at which receptor “fires”
Lowest detectable stimulus intensity
- influenced by practice, fatigue, aging, injury
I.e. pain threshold in competitive state vs non-competitive state, and post injury (protective and sensitive)

22
Q

Stimulus duration?

What’s it coded by?

A

Length of time for stimulus application

Coded by duriation of AP firing

23
Q

Perceived vs sustained duration

A

Perceived duration of application (and intensity) may vary, sustained duration means intensity of perveived stimulus diminishes over time

24
Q

Why does sustained duration happen?

A

Adaptation - intensity of perceived stimulus diminishes over time coded by firing frequency and duration

25
Q

Receptor adaptation

A

Mechanoreceptors show diff firing patterns to code duration

Cutaneous and subcutaneous mechanoreceptors - low threshold/high sensitivity

26
Q

Rapidly vs slowly adapting receptors

A

Slowly - contribute to fire as long as stimulus is maintained - changing shapes
Rapidly - falls silent even when stimulus is maintained - movement and stimulus

27
Q

Stimulus location

A

Site of stimulation - where applied

28
Q

Why are we able to localize where stimulus occurs

A

Body mapped on sensory cortex(post central gurus) - sensory map/homunculus - somatotropin Oder in the human primary somatic sensory cortex -lips, hands, fingers, genitalia (cortical tissue)
Species specific - for racoons its paws

29
Q

Variation in sensitivity of tactile discrimination is a function of

A

location of body surface

30
Q

Variation in tactile discrimination due to 2

A

Varying receptor density throughout body - more receptors=more sensitivity - finger vs back because finger needs a to manipulate
Regional diff in “receptive field” - input area for the receptor - arm larger, finger small

31
Q

Receptive fields (of a somatosensory afferent fibre)

A

The total area of the skin surface within which suitable stimulation will evoke a response (change in firing state) in the afferent fibre

32
Q

All somatic sensory info conveyed by

A

Overlaps of receptor fields and receptor types

33
Q

Where does the sensory information go?

A

Inputs from afferent neurons are transmitted to the brain to provide sensory awareness - all somatic sensory info conveyed by pseudounipolar neurons in the dorsal root ganglia

34
Q

How many groups of somatosensory tracts? What are they?

A 
6 - peripheral and central axons 
Dorsal column medial lemniscus pathway 
Spinothalamic tracts 
Spinocerebellar tracts 
Spino-Olivary tracts 
Spinotectal tracts - textile 
Spinoreticular tracts - reticular
35
Q

Somatosensory info is transmitted from thalamus to what three regions of in parietal lobe?

A

Primary somatosensory area (SI) - post central gyrus
Secondary somatosensory area (SII) - by lateral sulcus
Posterior parietal area

36
Q

3 steps of sensory neuron input

A

Sensory receptors reside at the terminal of peripheral branch
Central branch leads to spinal cord
Cell body located in ganglion external to spinal cord

37
Q

How is the somatosensory system organized? 3

A

Typographically
Areas of body where skin is densely populated by mechanoreceptors have large cortical representation
Size of receptive fields of afferent fibres INNERVATION gets the mechanoreceptors is an important determinant of tactile sensitivity

38
Q

What does aging do to the number of receptors?

A

Decreases

39
Q

Clinical application of perceiving stimulus location

A

Two point discrimination - minimal inter-stimulus distance required to perceive simultaneously applied stimuli as distinct

40
Q

6th sense:

A

Sensory awareness: Kinaesthesia/ proprioception - awareness of the position and movement of segments of our body in space and in relation o one another - we dont notice it until it has been affected or we have to use it to compensate for something

  • static position sense - proprioception
  • dynamic position sense - kinaesthesia
41
Q

Proprioceptors

A

Special receptors that media kinesthesia/ proprioception

42
Q

Three sources of sensory fdbk contribute to kinesthetic sense

A

Articulate receptors: mechanoreceptors in joint capsule
Muscle mechanoreceptors: muslce spindle and GTO - length.tension
Cutaneous mechanoreceptors: macro discs

43
Q

Iwasa - proprioceptive improvement in knees with ACL surgery - 3

A

Assessed by joint angle reproduction
Significant diff from pre-operative state and 9 months
Continued improvement up to 8 months
Min of 18 months after ACL reconstracution may be needed for complete restoration of the proprioceptive function in knees

44
Q

What does full kinesthetic sensitivity depend on?

A

Combined actions of mechanoreceptors in muscles, joints and skin

45
Q

Sensory coding modalities

A

Type of information (vision, hearing) coded in 2 ways

46
Q

What are receptors sensitive to?

A

Different energy forms

47
Q

Labelled lines

A

Axons of receptors function as modality specific lines of communication between periphery and CNS

48
Q

2 point discrimination in

A

Regional difference

49
Q

Ventral and dorsal roots vs afferent and efferent

A

Ventral efferent dorsal afferent

50
Q

Dorsal root ganglia

A

Cell bodies of afferent neurons made of pseudounipolar neurons

51
Q

Ventral corticospinal tract supply

A

Neck and upper limbs

Motor Control (9 decks)

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