L2 - Sensory Processing

Question 1

What are qualia?

Answer 1

Perceived sensations

Question 2

What is the explanatory gap?

Answer 2

We can’t explain why we all perceive colours, sounds and smells differently

Question 3

Define an adequate stimulus

Answer 3

A physical or chemical stimulus that needsthe least energy to change the membrane potential of a sensory nerve cell

Question 4

Outline the law of specific nerve energies by Müller

Answer 4

The final CNS destination not the type of stimulus determines the quality of perception

Question 5

Outline Sperry’s experiments on the frog visual system

Answer 5

Severed optical tracts and connected them to the opposite sides to what they were originally. The frogs were confused as the cortical areas were the same as before therefore believed that what it was seeing with it’s right eye it was actually seeing with it’s left. This backs up the law of specific nerve energies

Question 6

What is the Anes room illusion?

Answer 6

A room designed with forced perspective. This shows us that we are conscious of sensations/percepts not of physical reality

Question 7

What are the senses for physical stimuli?

Answer 7

Mechanical senses
Temperature
Vision
Electric
Magnetoreception

Question 8

What are the sense for chemical stimuli?

Answer 8

Olfaction

Gustation

Question 9

What is proprioception?

Answer 9

the position of one’s own body in space

Question 10

What is interoception?

Answer 10

Sense of the physiological condition of the body e.g. hunger, thirst etc.

Question 11

What are primary sensors?

Answer 11

They cell detects the stimulus and directly sends an AP

Question 12

What are secondary sensors?

Answer 12

The cell detects the stimulus which is then passed onto a secondary cell where it is transformed into an AP

Question 13

What is transduction?

Answer 13

Conversion of a stimulus into a bioelectrical signal

Question 14

What is transformation?

Answer 14

Conversion of an electrical signal into an AP train

Question 15

What is conduction?

Answer 15

Passing on of the electrical signal

Question 16

What are the properties of a sensor potential?

Answer 16

Graded, no threshold
Summation possible as no refractory period
Usually depolarising
Local potential
Electrotonic conduction

Question 17

What is the wave code?

Answer 17

Frequency of an AP dependent on the intensity of the stimulus

Question 18

Outline the experiment which tested light detection int he Horsehoe Crab compound eye

Answer 18

Increasing light intensity led to increased AP frequency
Increased length of stimulus led to increased length of AP train
The coding of sensory information is encoded via a temporal pattern of a sequence of APs. The analog sensor potential is transformed into a digital representation.

Question 19

What are the receptor response types and outline them?

Answer 19

Proportional - tonic, static. The sensor encodes the stimulus based on strength
Differential - phasic. The sensor reacts to the speed of the stimulus change
Proportional-Differential response type - Encode stimulus amplitude and convert fast changes into higher AP rates

Question 20

What is adaptation?

Answer 20

Decrease of tonic response over time to a persistent stimulus

Question 21

What is habituation?

Answer 21

Decreased reaction of an organism to ongoing or repetitive stimulation

Question 22

What is a receptive field?

Answer 22

The particular region of the sensory space in which a stimulus will trigger the firing of that neuron

Question 23

Why overlap receptive fields?

Answer 23

To create a much more complicated receptive field at the cortical level

Question 24

What is psychophysics?

Answer 24

The scientific study of he relationship between physical stimuli and the perceptions evoked by the stimulus

Question 25

What are the two types of sensory detection threshold?

Answer 25

Absolute threshold

Just Noticeable Difference (JND)

Question 26

What is Weber’s Law?

Answer 26

With increasing stimulus intensity R the absolute perceptible difference delta R also increases the relativ eperceptible difference delta R/R is constant

Question 27

What is the law of Weber-Fechner?

Answer 27

The perceived intensity E is logarithmically dependent on the relative stimulus intensity

Question 28

Why is the nervous system optimized to detect relative differences?

Answer 28

To adapt to changing environments

Question 29

What is the psychometric function?

Answer 29

It models the relationship between a given feature of the physical stimulus and the forced choice responses of the subject.

Question 30

Outline Newsome’s experiment Motion detection in the cortical area MT

Answer 30

A monkey had to detect coherent motion. The physical stimulus intensity was the percentage of coherently moving points. The greater the coherence the greater the firing in one direction detection.
MT = medial temporal area int he visual cortex