Nociception

Question 1

Are are the 5 types of threshold

Answer 1

Perception threshold- weakest stimuli can be detected
Absolute threshold- lowest level detected
Recognition threshold- detected and also recognised
Differential threshold- change in detected stimuli that can be perceived
Terminal threshold- level beyond which stimuli no longer detected

Question 2

Describe stereognosis

Answer 2

• ability to understand object by touch
• segregated LTM info arrives in contra cortex (somatotopy maintained)
• info combined to form precept

Question 3

Describe Asterognosis

Answer 3

• impaired object recognition

- intact perception

Question 4

What did micromapping reveal

Answer 4

1. Columnar and topographical organisation of cortex
2. Neuronal populations have defined
   - modalities
   - adaption rates
   - receptive fields (larger than primary afferent due to convergence)
   - grouped by function

Question 5

Describe the columnar arrangement of the somatosensory cortex

Answer 5

• columns relate to specific location and receptor type

- excitatory and inhibitory connections lead to ‘feature extraction’

Question 6

Role of Pyrmidal cells/ stellate cells

Answer 6

Pyramidal: longer axons to connect parts of the brain

Stellate cells: shorter axons to transfer info in the cortex

Question 7

What layer does somatosensory Info enter

Answer 7

From thalamus to layer 4

Question 8

Where is the primary somatosensory cortex located

Answer 8

1. Post-central gurus

2. In Parietal lobe

Question 9

Describe labelled line theory

Answer 9

1. Overlapping receptive fields from Rapid adapting and SA receptors project to separate alternating columns
2. Receptive field gets larger at each level of processing

Question 10

What are the 3 types of feature detection neurones

Answer 10

• motion sensitive
• direction sensitive
• orientation neurones

Question 11

How is direction sensitivity produced

Answer 11

1. Excitatory receptive fields are aligned along preferred axis
2. If stimuli is not preferred, it will hit an inhibitory field first and no firing will occur