Chapter 13 - Touch 3

Question 1

How to measure sensitivity to mechanical pressure

Answer 1

Esthesiometer - set of calibrated fibres with different diameters, each produceing a differnt force when applied (smaller diameter = less force), used to determine thresholds
- higher the threshold the less sensitive

Question 2

How sensitive are we to changes in tactile vibrations

Answer 2

Vibrotactile Stimulation - change in pressure over time
- maximum sensitivity happens at 200hz
- overall cue reflects the contributions of different mechanoreceptors populations (SA1, FA1, FA11) at different levels of vibration

Absolute vibratory threshold - minimum amount that a vibrating stimulus displaced the skin it to be detected

Question 3

How finely can we resolve spatial details

Answer 3

Two-point limin/ touch threshold- smallest seperation of 2 points applied on the skin which can still be detected (compass)

Two-point pain threshold - smallest seperation of 2 painful stimuli applied together that can be differneitated

• those that have high detection thresholds have low spatial acutity

Question 4

Mechanoreceptor properties and 2-point discrimination

Answer 4

associated with - smaller mechanoreceptor field, higher density of mechanoreceptors

• signals must not converge on their way to the cortex
• spatial acutity is mediated by superfical fibres

Question 5

Groups of people that have high tactile sensitivity

Answer 5

• gender - women becaue smaller hands = more spatial acuity
• age - brail readers use hands more and pianists
• genetics - autism hypersensitivity, runs in genes

Question 6

Touch Adaptation

Answer 6

• occurs in response to prolonged, steady stimulation
• promoted by:
  large stim area, weaker intensity force, stimulating less-sensitve areas of the body
• adaptation cannot only be explained by reduced mechanorecepotr discharge