Sensorimotor System

Question 1

How is sensory stimuli detected?

Answer 1

Receptor cells detect the different forms of energy.

Question 2

What is transduction?

Answer 2

The process of taking energy and changing into to electrical signals which the brain can understand.

Question 3

What are examples of ionotropic sensory receptors?

Answer 3

Mechanoreceptors: pressure opens an ion channel
Thermoreceptors: relate to changes in temperatures and there are different thermoreceptors for cold vs warmth

Question 4

What are examples of metabotropic sensory receptors?

Answer 4

Chemoreceptors determine chemicals related to taste or smell.
Photoreceptors: light alters the receptor protein.

Question 5

What are modalities?

Answer 5

A medium of sensation such as hearing or vision.

Question 6

Explain what labelled lines are.

Answer 6

Specific pathways that take transduced energy into the brain.

Question 7

What is the relationship between labelled lines and modalities?

Answer 7

Each modality has its own labelled line, and each labelled line has other labelled lines for subdivisions of the modality.
Example: touch has its own labelled line, but there are different labelled lines for warmth, cold, pressure, etc.

Question 8

Explain the path sensory info takes.

Answer 8

1. Sensory info enters the CNS either through the brainstem (cranial nerves) or the spinal cord (spinal nerves).
2. Info gets sent to the thalamus which then takes the info and sends it to the cerebral cortex.
   - Each modality has an area of the cortex that receives info from the thalamus (the primary sensory cortex).
3. Primary sensory cortex swaps info with the nonprimary sensory cortex.

Question 9

Define proprioception.

Answer 9

Our brain’s ability to be aware of our body’s position in space.

Question 10

What is interoception?

Answer 10

Interoception takes care of basic bodily functions such as heart rate and breathing.

Question 11

What is exteroception?

Answer 11

The sensitivity to stimuli outside of our body.

Question 12

What are cutaneous receptors?

Answer 12

Receptors for exteroception that are in the skin.

Question 13

Are Pacinian corpuscles ionotropic or metabotropic?

Answer 13

Ionotropic

Question 14

How is a Pacinian corpuscle structured?

Answer 14

There are layers of membrane called corpuscle that surround an afferent nerve ending which creates the action potential.

Question 15

How do Pacinian corpuscles create an action potential?

Answer 15

The ion channel in Pacinian corpuscles are blocked by protein plugs. The corpuscles can be stretched by vibrations and if the vibration is strong enough, the plug moves and Na+ ions flood the nerve ending which creates an EPSP and possibly an action potential.

Question 16

Explain what a receptive field is.

Answer 16

A portion of sensory space that can elicit neuronal responses when stimulated.
Example: Neuron A responds to a touch on a specific part of the foot, which Neuron B which is only a few inches away from A in the cortex only elicits a response when the elbow is touched.

Question 17

Explain the steps of a somatosensory pathway.

Answer 17

1. Cutaneous receptors take somatosensory info and send an action potential into the dorsal root ganglia. The info is then carried into the spinal cord through axon, then through the white matter and into the medulla.
2. Neurons that received the info in the medulla send axons across the midline then dorsally into the thalamus.
3. The left thalamus deals with info from the right side of the body and vice versa.
4. Info from the thalamus then goes into the primary somatosensory cortex.

Question 18

If touch receptors above the head receive stimuli, how does info reach the central nervous system?

Answer 18

Through the cranial nerves in the brainstem.

Question 19

Which nerves are used when touch receptors below the head are stimulated?

Answer 19

Through the spinal nerves.

Question 20

What are dermatomes?

Answer 20

Slices of the body that are innervated by left and right dorsal roots of a segment of the spinal cord.

Question 21

Where is the primary somatosensory cortex located?

Answer 21

Posterior to the central sulcus, therefore in the parietal cortex. The postcentral gyrus and the primary somatosensory cortex are the same part of the brain.

Question 22

Explain the map of our body made in the primary somatocortex.

Answer 22

The parts of our body that are more sensitive to touch are overrepresented in the primary somatosensory cortex.
Example: the hands have lots of touch receptors and therefore make up a larger part of the primary somatosensory cortex.

Question 23

What is the association cortex?

Answer 23

The association cortex deals with many modalities and labelled lines in order to create an integrated sensory perception.