Sensor

Question 1

What is a receptor cell?

Answer 1

specific sensitive cell that receives the stimulus and converts it into receptor potential (electric potential).

Question 2

Receptor cells of sensory organs are sensitive specifically for ___

Answer 2

one type of physical or chemical stimulus

Question 3

Receptor cells of sensory organs are sensitive specifically for one type of physical or chemical stimulus (e.g., light, sound, etc.).

→ This stimulus causes a change in the ___, resulting in the generation of the __

Answer 3

• resting potential
• receptor potential.

Question 4

What is receptor potential?

Answer 4

local (non-propagating) change of membrane potential of the receptor cell.

→ Its amplitude depends on the stimulus intensity.

Question 5

What is dynamic compression?

Answer 5

In the case of weak stimuli, the relative change of the receptor potential is greater than in case of strong stimuli.

→ Sensitivity of the receptor cell depends on the strength of the stimulus (this usually follows a power function).

Question 6

Sensitivity of the receptor cell depends on the __

Answer 6

strength of the stimulus (this usually follows a power function).

Question 7

What is ACTION POTENTIAL (AP)?

Answer 7

a short electric voltage pulse (~ ms) of constant amplitude (~ 0.1V) which propagates rapidly along the neural axon.

→ Its main variables are the activation threshold and the repetition frequency.

Question 8

What is sensory nerve?

Answer 8

nerve bundle that converts the receptor potential exceeding a threshold level into action potential (AP), and transfers the frequency-coded information (series of AP) from the receptor cell to the CNS.

Question 9

The sensory nerve cell, which is connected to the receptor cell, converts the ___ into the train of uniform electric pulses called action potentials

Answer 9

receptor potential (above a threshold)

Question 10

In most cases, what is the relationship between The frequency of the action potential and the receptor potential amplitude?

Answer 10

The frequency of the action potential is proportional to the receptor potential amplitude in most cases.

Question 11

Why can the coded information arrive unchanged and undamped to the respective sensory center of the brain?

Answer 11

Because the amplitude of the action potential does not change during its propagation along the nerve

Question 12

Because the amplitude of the action potential does not change during its propagation along the nerve, the coded information arrives unchanged and undamped to the respective ___

Answer 12

sensory center of the brain,

Question 13

What is sensory center of the brain?

Answer 13

where sensation is generated as a result of complex processes.

→ The strength of sensation corresponds to the frequency of the action potential.

Question 14

For reading only

Answer 14

The lower part of Fig. 1 represents the block diagram of one possible electronic model of the sensory system, which we will use during the measurement.

Question 15

What are receptor cells of the retina?

Answer 15

rods and cones.

Question 16

The model of the photoreceptor shown here corresponds to the ___

Answer 16

cones that are responsible for daylight vision.

Question 17

THE LIGHT SENSOR MODEL

The instrument in our measurement is a model of the (1)____, thus the physical signal energy is represented by (2)___ (Fig. 1, lower part).

→ The electronic amplifier subsequent to the photoreceptor (transducer) amplifies and compresses the electronic signal corresponding to the light stimulus.

Answer 17

1. retina
2. light

Question 18

THE LIGHT SENSOR MODEL

The instrument in our measurement is a model of the retina, thus the physical signal energy is represented by light (Fig. 1, lower part)

→ The electronic amplifier subsequent to the ___ (transducer) amplifies and compresses the electronic signal corresponding to the light stimulus.

Answer 18

photoreceptor

Question 19

THE LIGHT SENSOR MODEL

The instrument in our measurement is a model of the retina, thus the physical signal energy is represented by light (Fig. 1, lower part)

→ What is the role of The electronic amplifier subsequent to the photoreceptor (transducer)?

Answer 19

It amplifies and compresses the electronic signal corresponding to the light stimulus.

Question 20

THE LIGHT SENSOR MODEL

The instrument in our measurement is a model of the retina, thus the physical signal energy is represented by light (Fig. 1, lower part).

→ The electronic amplifier subsequent to the photoreceptor (transducer) amplifies and compresses the electronic signal corresponding to the light stimulus.

→ Here we can measure the signal corresponding to the ___

Answer 20

receptor potential.

Question 21

THE LIGHT SENSOR MODEL

The instrument in our measurement is a model of the retina, thus the physical signal energy is represented by light (Fig. 1, lower part).

→ The electronic amplifier subsequent to the photoreceptor (transducer) amplifies and compresses the electronic signal corresponding to the light stimulus.

→ Here we can measure the ___ corresponding to the receptor potential.

Answer 21

signal

Question 22

THE LIGHT SENSOR MODEL

The instrument in our measurement is a model of the retina, thus the physical signal energy is represented by light (Fig. 1, lower part).

→ The electronic amplifier subsequent to the photoreceptor (transducer) amplifies and compresses the electronic signal corresponding to the light stimulus.

→ Here we can measure the signal corresponding to the receptor potential.

→ The subsequent voltage-to- frequency converter generates the ___, which can be displayed on an oscilloscope.

Answer 22

pulse train similar to the action potential

Question 23

HOW THE SENSOR MODEL WORKS

Structure of the light sensor of the model equipment

Answer 23

The light sensor of the model equipment is a silicon photodiode located behind the input aperture (center of the iris) inside the box

Question 24

HOW THE SENSOR MODEL WORKS

In the first phase of signal processing, the electric signal of the photodiode is (1)___ and (2)____ by a special amplifier

→ Direct current of the (3)___ can be measured at this stage.

Answer 24

1. amplified
2. compressed
3. RECEPTOR POTENTIAL

Question 25

**HOW THE SENSOR MODEL WORKS** In the second part of the signal processing, the receptor potential is converted into a train of (1)\_\_\_ by a so-called (2)\_\_\_. The pulse frequency is proportional to the (3)\_\_\_ at any time.

Answer 25

1. square pulses 2. **voltage-to- frequency converter** 3. **receptor potential**

Question 26

**HOW THE SENSOR MODEL WORKS** In the first phase of signal processing → 2nd phase of signal processing → Finally, a shape-forming circuit generates a signal similar to the real \_\_\_, that can be visualized on the screen of the oscilloscope.

Answer 26

**ACTION POTENTIAL**

Question 27

**HOW THE SENSOR MODEL WORKS** In the first phase of signal processing → 2nd phase of signal processing → Finally, a shape-forming circuit generates a signal similar to the real **ACTION POTENTIAL**, that can be visualized on the screen of the oscilloscope.

Answer 27

oscilloscope

Question 28

What is illuminance?

Answer 28

Total luminous flux incident on a surface per unit area. The unit of illuminance is the lux ( lx). Illuminance at 1 m distance from a candle is 1 lx (lux), under strong sunshine it is 100 000 lx.

Question 29

What is WEBER-FECHNER’S LAW?

Answer 29

logarithmic relationship between sensation and relative stimulus which became obsolete with the more accurate Stevens’ power law.

Question 30

What is loudness?

Answer 30

expresses the real loudness sensation in Sone units calculated according to Stevens’ power law.

Question 31

What is STEVENS’ POWER LAW?

Answer 31

relationship between sensation (􏱤 ) and relative stimulus (􏱥 */*􏱥0) in a form of power function as 􏱤 = const (􏱥 */*􏱥0) *n*, where the exponent *n* is characteristic for the modality of sensation. For example, for loudness *n* = 0.3, and for light sensation *n* = 0.5.

Question 32

**PLAN OF THE MEASUREMENT** Set the first (1)\_\_\_ to 10 klx (kilolux). To achieve this, place the luxmeter on the base of the stand so that its aperture is vertically under the light source.

Answer 32

**recommended illuminance value**

Question 33

**PLAN OF THE MEASUREMENT** Set the first **recommended illuminance value** to 10 klx (kilolux). To achieve this, place the luxmeter on the base of the stand so that its aperture is vertically under\_\_\_

Answer 33

the light source.

Question 34

**PLAN OF THE MEASUREMENT** make a note of \_\_\_\_ → Remove the luxmeter and place the sensor model box under the glass fiber bundle so that the center of the aperture falls exactly in the same position where the luxmeter aperture was before. → Read and make note of the **receptor potential** (voltage) from the voltmeter in Volt units. → Measure the **time period** in **ms** (millisecond) units between the **action potentials** on the oscilloscope screen

Answer 34

**the measured value of illuminance**

Question 35

**PLAN OF THE MEASUREMENT** make a note of **the measured value of illuminance** → Remove the luxmeter and place the sensor model box under the glass fiber bundle so that the center of the aperture falls exactly in the same position where the \_\_\_ → Read and make note of the **receptor potential** (voltage) from the voltmeter in Volt units. → Measure the **time period** in **ms** (millisecond) units between the **action potentials** on the oscilloscope screen

Answer 35

luxmeter aperture was before.

Question 36

**PLAN OF THE MEASUREMENT** make a note of **the measured value of illuminance** → Remove the luxmeter and place the sensor model box under the glass fiber bundle so that the center of the aperture falls exactly in the same position where the luxmeter aperture was before. → Read and make note of the\_\_\_ from the voltmeter in Volt units. → Measure the **time period** in **ms** (millisecond) units between the **action potentials** on the oscilloscope screen

Answer 36

**receptor potential** (voltage)

Question 37

**PLAN OF THE MEASUREMENT** make a note of **the measured value of illuminance** → Remove the luxmeter and place the sensor model box under the glass fiber bundle so that the center of the aperture falls exactly in the same position where the luxmeter aperture was before. → Read and make note of the\_\_\_ from the voltmeter in Volt units. → Measure the (1)\_\_\_\_between the (2)\_\_\_ on the oscilloscope screen

Answer 37

1. **time period** in **ms** (millisecond) units 2. **action potentials**

Question 38

As the action-potential frequency is proportional to the **strength of light sensation,** which law is valid? Describe it

Answer 38

The **psychophysical law, called Stevens’ power law**

Question 39

Principle of **LOUDNESS MEASUREMENT**

Answer 39

We will measure the relationship between the objective sound intensity and the subjective psychophysical loudness.

Question 40

Items used in **LOUDNESS MEASUREMENT**

Answer 40

* arbitrary waveform generator in harmonic mode (sinusoidal) 􏱛 * headphones

Question 41

In the loudness versus sound intensity graph (Fig. 7 bottom panel) the theoretical **Stevens’ power law** of **loudness** scaled in ___ units,

Answer 41

**Sone**

Question 42

In ___ graph (Fig. 7 bottom panel) the theoretical **Stevens’ power law** of **loudness** scaled in Sone units,

Answer 42

the loudness versus sound intensity

Question 43

the **Weber-Fechner** type of **loudness level** ## Footnote **→ Scaled in ___ unit**

Answer 43

**Phon**

Question 44

In the loudness versus sound intensity graph (Fig. 7 bottom panel) the theoretical ___ scaled in Phone units,

Answer 44

the **Weber-Fechner** type of **loudness level**

Question 45

Describe sone scale

Answer 45

A subjective perception of loudness level. Based on the observation that every 10 phon increase in loudness level is perceived as a doubling of the sound sensation. 1 son = 40 phon, 2 son= 50 phon, etc.

Question 46

Describe The phon scale.

Answer 46

represent the loudness level according to weber-fechner law which describe the sensation as a log function of the relative stimuli, expressed in decibel. (not accurate as sone scale)

Question 47

Steps of sensory signal transduction.

Answer 47

Stimulus → Receptor potential (on sensory receptor) → Action potential (on nerve cell) → CNC

Question 48

Classification of receptors cell according to stimulus

Answer 48

* Photoreceptor * Chemoreceptor * Thermoreceptor * Mechanoreceptor * Baroreceptor

Question 49

Classification of receptors cell according to location

Answer 49

1. Interoreceptor 2. Exteroreceptor 3. Proprioreceptor

Question 50

Classification of receptors cell according to complexity

Answer 50

Question 51

What are 5 modalities?

Answer 51

Vision, hearing, touch, taste, smell

Question 52

What is threshold stimulus?

Answer 52

The stimulus intensity needed to evoke sensation

Question 53

What is Information coding by the receptor potential?

Answer 53

**Amplitude coding, where the intensity of the stimulus corresponds to the receptor potential.**​ When the stimulus exceeds a given threshold, an action potential will be generated.

Question 54

What is Information coding by the action potential?

Answer 54

Frequency coding, where the increase in the voltage of the receptor potential will lead to higher frequency of the AP of nerve. gives information about:​ * modality (type) (depends of which nerve does the AP) * intensity (strength) frequency coding * duration * localization

Question 55

What is adaptation?

Answer 55

A negative feedback in which almost all sensory organs respond by a decreasing sensation to constant stimuli

Question 56

2 types of threshold stimulus

Answer 56

* Absolute threshold stimulus * Relative threshold stimulus

Question 57

What is Absolute threshold stimulus

Answer 57

It is determined by using idealized circumstances of sensation

Question 58

What is relative threshold stimulus?

Answer 58

It is distinguished in the presence of background noise of a given intensity. → The difference between a background intensity and a different intensity that can barely be distinguished from it → relative threshold stimulus

Question 59

Describe compressive sensing?

Answer 59

* According to Steven's Power law, sensation is a power function of the stimulus strength * The exponent ‘n’ is a constant specific type of sensation and Oo is the absolute threshold stimulus → **If n \< 1, the function is called compressive**

Question 60

Describe expansive sensing

Answer 60

* According to Steven's Power law, sensation is a power function of the stimulus strength * The exponent ‘n’ is a constant specific type of sensation and Oo is the absolute threshold stimulus → **If n \> 1, the function is called expansive**

Question 61

What are receptors with persistent action potentials?

Answer 61

Receptors that transform sensed stimuli into electric signals (into membrane potential changes)