Somatosensory and Pain

Question 1

What are somatosensory modalities?

Answer 1

Somatosensory helps the body detect and process sensory information. Somatosensory modalities are touch, pain, temperature, and proprioception.

Cutaneous (sensors in skin can detect): senses touch, pressure, vibration, heat, cold, pain, itch

Proprioception (internal sides, body’s position, or movement): muscle length, muscle tension, joint angle

Question 2

What can we detect using the systems we have?

Answer 2

Mechanical - touch, sound
Chemical - smell, taste
Electromagnetic - vision, temperature

Question 3

What is transduction?

Answer 3

Taking mechanical stimulation (touch) and turning it into electrical impulses

Question 4

What do sensory endings affect?

Answer 4

• • Optimal stimulus: depending on the kind of neurons, a muscle spindle has an organ associated with it so that when the muscles extends that muscle spindle afferent that axon is stimulated and fires action potentials and those action potentials will go on the nervous system.
• Adaptation properties: those axons may not be where adaptations happens
• Receptive field: How much of the world is a particular neuron listening to. Big receptive field (don’t know where out in the world things are happening)

Question 5

Sensory differ in axon diameter and myelination:

Answer 5

C-fiber small, no myelin

Question 6

Mechanoreceptors: Structure and location

Answer 6

Small field: shallow
Large field: deep

Question 7

Sensory Transduction & Coding:

Answer 7

A gentle poke to the skin. The extracellular indicates the action potential recorder extracellularly. Weak stimulus –> no action potential. The energy of that stimulus is going to be converted into an electrical signal. The stimulus and depolarization and see no action potentials.

Question 8

How is intensity coded?

Answer 8

How big the depolarization is.

Question 9

What happens when you reach threshold?

Answer 9

Can now see action potential extracellularly.

Question 10

In case of action potential how do you encode intensity

Answer 10

Action potential are all the same size –> rate coding. The bigger the stimulus is the bigger the action potential and the higher the rate. The more action potentials the more Ca+ goes into the terminal, the more neurotransmitters are released.
The more spikes the bigger the stimulus must have been.

Question 11

Sensory Adaptation. What does it mean to “adapt”?

Answer 11

Stimulus goes on and stays on.
Adaptation is when you stop responding even if the stimulus is still there.
In a slowly adapting cell, you get an initial burst of action potentials and then it keeps on firing. Stimulus is still there.
In a rapidly adapting neuron, the stimulus is still there but stops firing quickly.

ADAPTATION IS WHEN YOU STOP RESPONDING EVEN THOUGH THE STIMULUS IS STILL THERE.

Question 12

Receptor neurons can be:

Answer 12

Slowly adapting (“tonic”) –> saying stimulus is still there. For example, you may want to know where your limb is even if it’s been there for hours & will have receptors paying attention to that.

Rapidly adapting (“phasic”) –> only cares about change. Was it the same a minute ago –> yes –> respond. No –> no response.