Somatosensoriska systemet

Question 1

what is an advantage of population codes?

Answer 1

using low-/high-threshold neurons extends dynamic range of a sensory system, i.e. overcoms max firing rate imposed by absolute refractory period)
e.g.: rod cells activate in dim light -> max in daylight, cone cells not activated by dim light,, sense differences in daylight

Question 2

isomorphic representation

Answer 2

pattern of activated/silent receptors, e.g. when holding an object

Question 3

what are the two steps of sensory processing?

Answer 3

1. fragmentation of stimulus into compounds (encoded by individual neurons
2. assembly into internal representations (these are NOT mirrors, important features from the detailed receptor input might be exaggerated, others ignored)

Question 4

what type of neurons are first order afferents?

Answer 4

pseudounipolar (dendrite/axon continous, attached to cell body in ganglion by a single process)

Question 5

why are dermatomes tested for pain?

Answer 5

overlap of dermatomes is more extensive for touch/pressure/vibrations than pain/temperatures (yields more precise assesment)

Question 6

how are proprioceptors distributed in the body?

Answer 6

more like muscle innervation (NOT like dermatome)

Question 7

what role does inhibition play?

Answer 7

an important mechanism enchancing contrast!