Sensory System

Question 1

What is the sensory system?

Answer 1

It is part of the nervous system which give organism information about the external world and the organism internal state

Question 2

For each sense stated below please name the system and the type of receptor that is needed to detect the sense in the system.

Hearing

Sight

Taste

Smell

Touch

Balance

Vibration (fish, frogs)

Electric (electric fish, platypus)

Heat (Snake)

Magnetic

Answer 2

Hearing; Auditory System; Hair cells

Sight; Visual System; Photoreceptor

Taste; Gustatory System; Taste Buds

Smell; Olfactory System; Olfactory receptor

Touch; Somatosensory; free nerve ending

Balance; Vestibular; Hair Cells

Vibration; Lateral line system; Hair Cells

Electric; Electric System; Electrorecptors

Heat; Infra-Red System; Infra-Red receptors

Magnetic; Magnetic; Magnetoreceptors

Question 3

What is Transduction?

Answer 3

Singal from the environment must be transformed into neuronal activity.

The first step in perception of a stimulus

Question 4

Sensory receptor cells have mechanisms which act either _____ or ________ to either open or close ion channels.

Answer 4

Directly; Indirectly

Question 5

True or False: Receptor potential is different from post-synaptic potentials.

Answer 5

False

Receptor potential are very similar to postsynaptic potentials

Question 6

What is the general effect of either opening or closing ion channels?

Answer 6

Change in membrane potential

Question 7

Receptor potentials are ________, meaning the larger the magnitude of the stimulus the larger magnitude of the receptor potential

Answer 7

Graded –> does not trigger A.P.

Question 8

What is Modality?

Answer 8

Sensory modality refers to the type of information encoded by a receptor.

Receptors are selective for particular modularity.

Question 9

What are examples of receptors are selective for a particular modality?

Hint: Visual System, Somatosensory System

Why is modality important?

Answer 9

Photoreceptors in our eyes are sensitive to light but will not respond to sound.

Dorsal Root Ganglion cells will respond to touch on the skin, but will not respond to light shining on the skin.

The active cells tells the brain what sort of stimulus is present.

Question 10

Different receptors within a given sensory system can be ____________ in terms of what ____________.

Answer 10

Very specific; what stimuli they respond to.

Question 11

What are some examples of the species of different receptors in different systems?

Different photoreceptors respond to different wavelengths of light. This allows us to see different _______.

Different cochlear hair cells respond to different frequencies of sound, which allows us to hear different __________.

Different dorsal root ganglion cells respond to different stimuli allowing us to feel _____________.

Answer 11

Colors

Pitches

touch, pain, and temperature

Question 12

What is Turning Curves used for?

Answer 12

Used to determine a neuron’s selectivity for different stimuli.

To plot a cell response vs a physical feature of a stimulus

Question 13

The size of a receptor potential depends on the ________ of a stimulus.

Which receptor potential will generate more A.P.?

Answer 13

Intensity

Larger intensity

Question 14

What are the two ways that the duration of a stimulus can be encoded?

Answer 14

(i) Sensory neurons with tonic responses continue to fire as long as the stimulus is present
(ii) Sensory neurons with phasic responses adapt to the stimulus – they fire only when the stimulus is turned on or in some cases also when the stimulus is turned off.

Question 15

True or False: Phasic responses rely on habituation. Since habituation is common, sensory neurons with phasic responses (adaptation) are common in a higher level of the brain.

Answer 15

True

Question 16

True or False: Sensory receptors tend to be organized in a 2-D sensory receptor sheet.

Answer 16

True

Question 17

True or False: Only a few sensory cells encode the location of a stimulus by having a receptive field.

Answer 17

False

All sensory cells ( sensory receptors, but also all of the CNS neurons) encode the location of a stimulus by having a receptive field.

Question 18

True or False: A sensory cell’s receptive field is the location within the sensory receptor sheet in which the cell responds to stimuli.

Answer 18

True

Question 19

What are the maps?

Answer 19

Forms of the major organizing principle of the sensory system are that neurons in sensory areas of the sensory receptor sheet.

Question 20

If cells at location A are firing, what part of the body is being touched?

Answer 20

Thumb

Question 21

If cells at location C are firing, what part of the body is being touched?

Answer 21

Face

Question 22

Sensory maps tend to maintain ______________; cells next to each other in the brain tend to have receptive fields next to each other on the receptor sheet.

Answer 22

Nearest neighbor relationship

Question 23

Sensory maps are not perfect maps of the sensory sheet in that certain parts of the maps are __________.

Answer 23

Magnified

Question 24

Which parts of the somatosensory map are magnified?

Answer 24

Face, hand, foot ,tongue

Question 25

True or False: Map magnification has perceptual consequences.

Answer 25

True

Question 26

Do you think we are better or worse at discriminating touch on our finger which is magnified on the map or on our trunk which has less brain processing it?

Answer 26

Finger, the more brain the better you can process information

Question 27

What kind of receptive fields would the visual system correspond to?

Answer 27

Corresponding to a particular location on the retina

Question 28

What would happen if the adapting cells had a huge receptive field covering the entire retina?

Answer 28

See a red blur