Brainscape's Knowledge GenomeTM

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


See full index

Physiology of Cells 2002 > Lecture 17: Principles of Sensory Processing & Somatosensation > Flashcards

Lecture 17: Principles of Sensory Processing & Somatosensation Flashcards

1
Q

What are the different features of sensory stimuli? (4)

A

MODALITY, SPATIAL INFORMATION, INTENSITY, QUALITY

  1. Modality (the type of information encoded)
    E.g. light, sound, pain, heat, cold, smell, taste
  2. Spatial information (the location of the sensory information)
    - Can be: body location (e.g. pain, touch) or location in external space (e.g. light, sound)
  3. Intensity (how strong is that stimulus)
    - Perceived strength of stimuli
    - Does it reach the threshold?
  4. Quality (unique to individual senses)
    - E.g. colour, sharpness of pain, pitch of sound
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What forms of stimulus energy can we detect?

  • Modalities of stimulus energy: (4)
A
  1. Mechanical:
    – Sense of touch, limb position, hearing, balance
  2. Chemical:
    – Taste, smell
  3. Photic:
    – vision
  4. Thermal:
    – hot and cold
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do we detect and respond to sensory stimuli? (2)

A

1 * Each sensory system will selectively transduce a sensory stimulus into an electrical signal (i.e. an action potential)

2 * Made possible through the presence of specialised ion channels present in the membranes of sensory neurons

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

How do we detect and respond to sensory stimuli?

EXAMPLE STRETCH

A

An example:
- mechanosensitive neurons have stretch-activated ion channels to detect a stretch

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

Cellular basis for transduction of a sensory stimuli (nerve ending)

A

**Can occur directly through a nerve ending:

  1. Stimulus sensitive nonspecific cation channel
  2. Sensory receptor (modified ending of afferent neuron)
  3. Voltage-gated Na+ channel
  4. Action potential

—-Graded receptor potential in nerve ending
THRESHOLD
Action potential initiation
—> Propagated action potentials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Cellular basis for transduction of a sensory stimuli (receptor cell)

A

**Can occur via a specialised receptor cell:

  1. Graded receptor potential in receptor cell
  2. Graded generator potential in nerve ending
  3. Action potential initiation
  4. propagated action potentials
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Sensory neurons are specialised for different modalities

A
  1. taste
  2. smell
  3. somatosensory
  4. muscle
  5. hearing
  6. vision
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Cellular basis for transduction of a sensory stimuli

A
  1. Can occur directly through a NERVE ENDING
  2. Can occur via a SPECIALISED RECEPTOR CELL
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How do we encode the intensity of a sensory stimuli? (4)

A

A. RECEPTOR POTENTIAL: graded in amplitude and duration, proportional to the stimulus

B. INTEGRATIVE ACTION: transforms a receptor potential to an AP if the threshold is reached. Increase in stimulus intensity is coded into the frequency of AP firing

C. ACTION POTENTIAL

D. OUTPUT SIGNAL: transmitter release
from synaptic terminal. Amount of transmitter released is determined by the total number of APs per unit time

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

Accessory structures - WHAT ARE THEY?

A

Accessory structures play an important ROLE in determining HOW THE STIMULUS ENERGY GETS TO THE TRANSDUCING CELLS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Features of Accessory Structures: (3)

A

1 * Accessory structures DO NOT TRANSDUCE STIMULUS ENERGY

2 * Are NOT NEURONS OR RECEPTOR CELLS

3 * Can be CELLULAR OR NON-CELLULAR

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

The labelled line concept: Key principle?

A

EACHSENSORY RECEPTOR HAS ITS OWN UNIQUE PATHWAY from the RECEPTOR ITSELF TO SOMATOSENSORY CORTEX

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Examples of The labelled line concept:

A

Examples:
1 * E.g Trauma to the optic nerve generates a visual percept

2 * E.g. electrical stimulation of the auditory nerve generates a sound percept (tinnitus)

3 * We can exploit the labelled line concept for medical advances
* E.g. bionic ear or bionic eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The labelled line concept application: bionic eye (5)

A
  1. CAMERA:
    captures image and transmits data to an external, body worn processing unit.
  2. DATA PROCESSED: and sent to implanted system via external wire.
  3. IMPLANTED RECEIVER: passes signals onto retinal implant.
  4. IMPLANTED ELECTRODE ARRAY: stimulates retina
  5. ELECTRICAL SIGNALS SENT FROM RETINA: via visual pathway to vision processing centres in the brain.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Somatosensation?

A

The process that CONVEYS INFORMATION regarding theBODY SURFACE and its INTERACTION WITH THE ENVIRONMENT

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

Four modalities of somatosensation?

A

TOUCH, NOCIOCEPTION, PROPRIOCEPTION, TEMPERATURE
1. Touch

2.Nociception
(perception of pain)

  1. Temperature
  2. Proprioception (gives information about where different body parts are located)
    * Predominately from the muscles and joints
17
Q

Proprioceptive receptors: MUSCLE SPINDLE: 3

A

1 * Mechanosensitive nerve fibres wrap around the central part of the muscle spindle

2 * When stretched mechanosensitive ion channels are activated

3 * Respond to changes in LENGTH

18
Q

Proprioceptive receptors: GOLGI TENDON ORGAN (3)

A

1 * Nerve endings are interwoven between collagen fibres

2 * Muscle contracts→collagen fibres pulled→nerve endings compressed → activates mechanosensitive ion channels

3 * Respond to MUSCLE TENSION (FORCE)

19
Q

Proprioceptive receptors: JOINT RECEPTORS (3)

A

FREE NERVE ENDING IN JOINTS, CHANGES AP FIRING RATE THROUGH PARTICULAR RANGE OF MOTION = RESPOND TO JOINT POSITION AND ANGLE

1 * Free nerve endings innervate different regions around the joint

2 * Each nerve ending changes its firing rate as the joint passes through a particular range of motion

3 * Respond to JOINT POSITION/ANGLE

20
Q

What are thermoreceptors?

A

1 * Separate ‘cold’ and ‘hot’ receptors

2 * Thermosensitive nociceptors ACTIVATE ATTEMPERATURES which could ELICIT TISSUE damage (protective effect)

21
Q

Discovery of receptors involved in temperature and touch: 2021 Nobel prize

A

Temperature sensation by TRPV1 channels

Pressure sensation mediated by Piezo channels

22
Q

Thermoreceptors will adapt rapidly to changes in temperature EXPLAIN (3)

A

1 * GREATEST STIMULUS comes from the INITIAL TEMPERATURE

2 * A LARGER CHNAGE in temperature will CAUSE A GREATER CHNAGE IN FIRING RATE

3 * FIRING RATE RATE ADAPTS TO THE NEW TEMPERATURE

23
Q

Nociceptors - WHAT IS IT?

A

Nociceptors respond SELECTIVELY to NOXIOUS STIMULI that can DAMAGE TISSUE

24
Q

Some specifics of Nociceptors (2)

A

1 * Often have very high (or low) thresholds or very precise ones

2 * Can be thermal, chemical or mechanical

25
Q

Nociception can be fast or slow…WHY ..EXPLAIN

A

Due to two different classes of nerve fibres
1. a8, myelinated, fast, for small precise loclisation of pain, sharp pain
2. C fibres, not myelinated for dull pain, less localised and less precise.

A8
1. Conduction velocity
5-40 m/s
2. For: Fast sharp pain
3. Diameter: 2 – 5 μM
4. Myelinated? Yes
5. Receptive field: Small, precise localisation of pain

Group C fibres
1 - 0.5-2 m/s
2 - Slow dull pain
3 - 0.4 – 1.2 μM
4 -No
5 - Large, less precise localisation of pain

26
Q

Tactile receptors in the skin: cutaneous mechanoreceptors

For the modality of touch (6)

A

1 * Pacinian corpuscle (vibration and deep pressure)

2 * Ruffini’s corpuscle (deep pressure)

3 * Merkel’s receptor (light sustained touch)

4 * Meissner’s corpuscle (light fluttering touch)

5 * Hair endings (hair movement and gentle touch)

6 * Bare nerve endings (pain and temperature)

27
Q

Pacinian corpuscle: an example of an accessory structure (3)

A
  1. Key point: Accessory structures such as Pacinian corpuscle change the characteristics of the sensory information

2 *CONCENTRIC LAYERS OF LAMINAE ALLOW RAPID ADAPTATION TO THE ORIGINAL STIMULI.

3 * Only get a TRANSIENT CHANGE in receptor potential until a CHANGE IN PRESSURE OCCURS

28
Q

Receptor fields

A

Size of the receptor field is important for our ability to identify and localise a particular stimulus

29
Q

WHAT IS SPACIAL ACUITY?

A

Ability to distinguish between two spatially separate stimuli

30
Q

Spatial acuity DEPENDS ON …? (3)

A

1 * Density of receptors

2 * Size of receptive fields

3 * Central convergence and lateral inhibition

31
Q

Spatial acuity: Two-point discrimination test:

A
  • To distinguish between two
    points, each point must fall within the receptive field of two separate sensory receptors
32
Q

Lateral inhibition and central convergence - KEY POINT?

A

Key point: Central convergence and lateral inhibition RESTRICT THE SPATIAL SPREAD OF OG STIMULI.

33
Q

Lateral inhibition and central convergence:

MAKE STIMULI MORE ? RESULTS IN….

A
  1. Due to central convergence and lateral inhibition, the original stimuli is more ‘focused’ thus restricting the spatial spread on the original stimuli
  2. As a result, the spatial acuity improves.

Cortical representation of two stimuli applied to the skin, with and without lateral inhibition

34
Q

Summary

A
  • The sensory system encodes a vast array of stimulus features
  • Specialized ion channels and membrane proteins that transduce stimulus energy into action potentials with the assistance of accessory structures
  • Action potentials in ‘labelled lines’ generate specific sensory percepts
  • Somatosensation includes multiple sensory modalities (proprioception, temperature, nociception and touch)
  • The specific anatomical arrangement of sensory neurons (i.e. central convergence and lateral inhibition) allow the ability to distinguish between two points (spatial acuity)

Physiology of Cells 2002 (24 decks)

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