Introduction to Perception

Question 1

What are some examples of sensory Modalities?

Answer 1

1. Somatic Sensation (Discriminative Touch, Proprioception, Pain, Temperature)
2. Vision
3. Hearing
4. Balance
5. Olfactory
6. Gustatory

Question 2

What is a sub modality? Give an example.

Answer 2

Differences in the quality of the sensation being perceived.

Vision: color, distance, movement

Question 3

What is sensation?

Answer 3

Awareness due to stimulation of a sense organ

Question 4

What are the components of a sensory system?

Answer 4

1. Receptors (Sense Organs)
2. Pathways
3. Target Areas

Question 5

What are the common features of the sensory modalities?

Answer 5

1. A physical stimulus
2. Transformation of the stimulus into neuron signals.
3. A response to the signals in the form of a perception or conscious experience of sensation.

Question 6

What is perception?

Answer 6

An internal construction of the external world according to CNS constraints.

Ex. Taste, sound, smell, color tones

Question 7

What does a neural code do?

Answer 7

Describes the relationship between the activity in a specified neural population and its functional consequences.

Question 8

What are the 4 attributes of stimuli?

Answer 8

1. Modality
2. Location
3. Intensity
4. Timing/Duration

Question 9

What is a modality, give an example, and how do we code for it?

Answer 9

• Defines a general class of stimulus (ex. touch)

- We code for it by the stimulus energy and the RECEPTORS specialized to sense that energy.

Question 10

What is the labeled line code?

Answer 10

The coding mechanism for stimulus modality and is based on the specificity of response in receptors.

Question 11

What are sensory receptors?

Answer 11

• First cell in each sensory pathway

- specialized to transform stimulus energy into electrical energy (signals)

Question 12

How are sensory receptors classified?

Answer 12

• based on the type of stimulus energy that they are most sensitive to

Question 13

What are the properties of the modality?

Answer 13

1. Each receptor responds to a narrow range of stimulus energy
2. They transduce stimulus energy into electrical signals (receptor potentials).

Question 14

Which modalities use the Ionotropic mechanism?

Answer 14

• Somatosensory
• Viscerosensory
• Auditory
• Vestibular
• Gustatory

Question 15

Which modalitise use the Metabotropic Mechanism?

Answer 15

• Somatosensory
• Visual
• Olfactory
• Gustatory

Question 16

What is the location attribute of stimuli?

Answer 16

The spatial arrangement of activated receptors within a sense organ conveys information regarding the stimulus

Question 17

In the Somatosensory and Visual systems what kind of information does location convey?

Answer 17

the Receptors convey information about the location of the stimulus on the body or in space.
-location includes= discrimination of size, shape, and resolution of the fine details

Question 18

How is the location of the stimulus determined?

Answer 18

Receptive fields of sensory neurons.

• each receptor responds only to stimulation within its field
• the greater the area of stimulation, the greater number of receptors that are stimulated

Question 19

How does density of receptors affect the sensory system?

Answer 19

It determines how well the sensory system can resolve the detail of the stimuli in that area.
-Higher the density of receptors, the smaller the receptive fields, the finer the spatial resolution. (ex. 2 point discrimination)

Question 20

How are differences in receptor density reflected?

Answer 20

Topographical maps in the CNS

Question 21

How is spatial arrangement different in the auditory, vestibular, olfactory and gustatory systems?

Answer 21

The spatial arrangement of the receptors represents the energy spectrum of the modalities.
Ex. Auditory receptors are arranged according to the sound frequency to which they respond, not the location of the sound in space.

Question 22

How is intensity of a stimuli determined?

Answer 22

1. The amplitude of the receptor potential

2. Total number of active sensory neurons

Question 23

How is intensity of a stimuli represented?

Answer 23

1. Frequency of action potentials (frequency code)
2. Number of activated receptors ( population code)

Ex. If you pinch a pencil, receptors around fingers are already activated. However, if you pinch harder, the frequency will increase.

Question 24

How is Timing and Duration of a stimuli coded?

Answer 24

Represented by changes in the frequency of action potentials of sensory neurons

Question 25

What are Rapidly Adapting Receptors?

Answer 25

- Respond only at the beginning and end of a stimulus | - Signal the rate at which the stimulus is applied or removed

Question 26

What are Slowly Adapting Receptors?

Answer 26

- Respond to prolonged and constant stimulation | - Signal stimulus magnitude for minutes

Question 27

What constitutes the common plan of sensory systems?

Answer 27

1. Info is conveyed by populations of sensory neurons acting together 2. Info is processed in a series of relay nuclei 3. Inhibitory interneurons within each relay nucleus help sharpen contrast between stimuli

Question 28

How do neurons act together to convey information and how does this involve submodalities?

Answer 28

1. simultaneously activate receptors in parallel pathways 2. specific submodalities depend on the combined activity of populations of receptors sensitive to overlapping energy changes.

Question 29

Describe the order of relayed information

Answer 29

Population of Receptors (1st order neurons)--> 2nd order neurons--> Higher order neurons

Question 30

Do 1st or 2nd order neurons have a bigger receptor field? Why?

Answer 30

2nd order neurons have a bigger and more complex receptive field because they receive information from a population of receptors

Question 31

How do inhibitory neurons sharpen contrast between stimuli?

Answer 31

1. They produce inhibitory regions within the receptive fields of higher order neurons 2. This inhibitory region enhances the contrast between stimuli, improving the resolution of spatial detail.