General Sensory Neurophysiology

Question 1

What is receptor adaptation?

Answer 1

Receptors gradually become more resistant to a stimuli - a greater stimuli is needed for the receptor to transduce an action potential (aka desensitisation)

Question 2

What are the two types of receptor adaptation?

Answer 2

Tonic Adaptation - tonic receptors are slow to adapt, making them responsive to continuous stimuli

Phasic Adaptation - phasic receptors adapt quickly, making them responsive to quickly-changing stimuli

Question 3

What is a receptive field?

Answer 3

• A receptive field is the area that a certain neuron is able to sense
• The greater the receptive field, the less the sensitivity

Question 4

How can you further improve the sensitivity of a neuron, apart from having a smaller receptive field?

Answer 4

• Lateral Inhibition
• When one neuron’s receptive field is stimulated, it causes neighbouring neurons’ K+ ion channels to open (hyperpolarising them and decreasing their response time)

Question 5

What is the Labelled Line Coding theory?

Answer 5

• Different pathways are used to transmit different types of sensory input
• The brain is used to this, and associated all kinds of input coming through a certain pathway with the usual input
• This means that unusual input (trauma to the orbit) which is still transmitted via the same pathways (photoreceptors) is still perceived as the supposed input (bright flashes of light)

Question 6

Are there any neurons that don’t have receptive fields?

Answer 6

Yes, for sound

Question 7

Are there any neurons that don’t have receptive fields?

Answer 7

Yes, for sound