Lab 1

Question 1

Normal EEG tracing

Answer 1

A normal EEG tracing consists of waves of various frequencies. The dominant frequencies depend on several factors, including the state of wakefulness, the age of the subject, the location of the recording electrodes, and the absence or presence of drugs or disease. When a normal awake adult is relaxed with the eyes closed, the dominant frequencies of the EEG recorded over the parietal and occipital lobes are about 8 to 12 Hz, the alpha rhythm. If the subject is asked to open the eyes, the wave becomes less synchronized, and the dominant frequency increases to 13 to 30 Hz, which is called the beta rhythm. The delta (0.5 to 2 Hz) and theta (3 to 7 Hz) rhythms are observed during sleep

Question 2

Alpha rhythm

Answer 2

When a normal awake adult is relaxed with the eyes closed, the dominant
frequencies of the EEG recorded over the parietal and occipital lobes are about 8 to 12 Hz, the alpha rhythm.

Question 3

Beta rhythm

Answer 3

If the subject is asked to open the eyes, the wave becomes less synchronized, and the dominant frequency increases to 13 to 30 Hz, which is called the beta rhythm.

Question 4

Amplitude and frequency of the oscillations when the eyes are closed?

Answer 4

8-12 Hz

Larger amplitudes than beta

Question 5

Amplitude and frequency of the oscillations when the eyes are open?

Answer 5

13-30 Hz

Smaller amplitudes than alpha

Question 6

What causes the rhythmic oscillation of the EEG when the eyes are closed?

Answer 6

Alpha occurs in the brains of healthy and awake adults who are resting with their eyes closed. Disappear during sleep and they also vanish when the individual begins to concentrate on a specific task

Question 7

What causes the rhythmic oscillation of the EEG when the eyes are open?

Answer 7

Higher frequency waves that appear in people who are either concentrating on a task, under stress, or are in a state of psychological tension

Question 8

Explain how the EEG exhibits larger amplitude oscillations when someone closes their eyes than when their eyes are open

Answer 8

In general, the amplitude of the EEG increases as the frequency decreases
When someone closes their eyes, the alpha rhythm with a frequency of 8-12Hz is prominent
When someone opens their eyes, the alpha rhythm is reduced and the beta rhythm with a frequency of 13-30Hz becomes more evident

Question 9

Cortical evoked potential

Answer 9

is the specific activation of a particular population of cortical neurons in response to a defined stimulus

Question 10

Alpha vs Beta rhythm

Answer 10

Alpha waves are seen in the EEG during resting with eyes closed and the beta EEG is present when a person is alert/attentive and thinking actively

Question 11

Frequency of alpha rhythm

Answer 11

8-12 Hz

Question 12

Frequency of beta rhythm

Answer 12

13-30 Hz

Question 13

Visual evoked potential

Answer 13

The term visually evoked potential (VEP) refers to electrical potentials recorded from scalp overlying visual cortex that have been extracted from the electroencephalogram by signal averaging.Any abnormality that affects the visual pathways or visual cortex in the brain can affect the VEP.

Question 14

Visual evoked potential

Answer 14

The term visually evoked potential (VEP) refers to electrical potentials recorded from scalp overlying visual cortex that have been extracted from the electroencephalogram by signal averaging.Any abnormality that affects the visual pathways or visual cortex in the brain can affect the VEP.

Question 15

Biological data measurement

Answer 15

Input - amplification - filtering - sampling - display

Sampling is rate dependent and need a high enough rate to catch important events

Question 16

The overall idea of digital biological recording

Answer 16

The biological events we record in physiology are continuous. Using digital technology, continuous data is sampled at some interval, and then turned into numbers that are stored in a digital device.This data can be optimised to display data that best represents real events by amplifying the signal, filtering out noise and selecting an appropriate sampling rate.

Question 17

Scope mode

Answer 17

Used to record very rapid events over short periods

Question 18

Chart mode

Answer 18

used for recording continuous events

Question 19

Sampling rate

Answer 19

A correct sampling rate is essential to recording good quality data

Question 20

Importance of the correct sampling rate for the finger transducer experiment

Answer 20

While the waveform you are recording looks like a continuous signal, digitised data is not continuous. The signal that enters the Powerlab from the finger pulse transducer is sampled at discrete and seperate intervals (determined by the sampling rate) and each data point is then connected by a series of lines to complete the waveform

Question 21

High sampling rate

Answer 21

If the sampling rate is sufficiently high, then the sampled points are close together and there is very little data loss

Question 22

Low sampling rate

Answer 22

If the sampling rate is too low, then data can be lost in-between each discrete sample

Question 23

Out of 4/s and a 1k/s sample rate which one gives the most accurate recording of a pulse wave?

Answer 23

1k/s

Question 24

The _____ pattern will affect the pulse wave amplitude over time (finger pulse transducer)

Answer 24

Breathing

Question 25

What effect does breath holding have on the pulse wave form?

Answer 25

It decreases the amplitude therefore the pulse gets weaker

Question 26

Overall idea of sample rate

Answer 26

If the sampling of data occurs more frequently then the trace will be more representative of the actual physiological phenomenon

Question 27

Frequency

Answer 27

1/duration

Question 28

Electrical waveform of the EEG depends on our ...

Answer 28

State of consciousness

Question 29

EEGs are recorded by

Answer 29

placing electrodes on the surface of the head - different recordings can be made from different parts of the brain, depending on where the electrodes are placed. Neurons closest to the electrodes will generate the largest signal

Question 30

Noise artifacts in EEG

Answer 30

Large spike are noise artefacts dur to the signals caused by blinking and the eyes opening/closing

Question 31

Why is important that the subject does not move during the EEG recording?

Answer 31

Movement will generate electrical noise from muscle activation

Question 32

Synchronised activity in an EEG recording trace

Answer 32

* Firing of large numbers of EPSPs OR IPSPs at one time * Similar signals occurring at the same time sum together * Prominent alpha waves * Occurs when ‘eyes closed’

Question 33

Desynchronised activity in an EEG recording trace

Answer 33

``` • Firing of both EPSPs AND IPSPs at the same time. • The opposing signals will cancel each other out • No/neligible alpha waves • Occurs when ‘eyes open’ ```

Question 34

Most appropriate sampling rate for the EEG recording to capture alpha waves? (1, 10, 20 Hz or 1kHz)

Answer 34

1kHz To ensure that 8-12 Hz alpha waves are recorded, need a sampling rate that is higher than the expected maximum value of the recording Sampling rate needs to be high enough to take many samples per event (each alpha wave) so that the trace will be representative of the actual physiological recording

Question 35

Synchronised activity eyes open or closed

Answer 35

Eyes closed

Question 36

Desynchronised activity eyes open or closed

Answer 36

Eyes open

Question 37

Alpha waves for synchronised activity

Answer 37

Prominent peaks at 8-12Hz which is the alpha rhythm

Question 38

Alpha waves for desynchronised activity

Answer 38

No prominent peaks

Question 39

If EPSPs summate for synchronised activity then ...

Answer 39

Will get a bigger alpha between 8-12 Hz

Question 40

VEP

Answer 40

Visual evoked potential is a type of CEP evoked by a visual stimulus

Question 41

VEP form

Answer 41

Is usually a triphasic form with a major peak (P100) flanked by 2 smaller peaks of opposite polarity

Question 42

P100 VEP

Answer 42

P100 is where the waveform peaks at about 100ms and it is thought to be generated by activity in the optic radiations which project to the visual cortex, and in the visual cortex itself

Question 43

Small early peak and small late peak VEP

Answer 43

The small early peak might result from activation of the lateral geniculate nucleus and the late peak from activity in the visual association cortex

Question 44

What is responsible for the delay between the stimulus and the P100?

Answer 44

Phototransduction, signal transmission, synapses

Question 45

CEP

Answer 45

cortical evoked potential is a stereotypical electrical response to a specific stimulus

Question 46

Latency

Answer 46

The time delay between a stimulus and a response

Question 47

Slow wave form peak than P100 would indicate...

Answer 47

Slower would means demyelination, slower reaction times etc

Question 48

Sample mean

Answer 48

Which represents our best guess at the mean from the population

Question 49

Sample standard deviation

Answer 49

Which gives an estimate of sampling precision/variance | measure of how spread out the numbers are

Question 50

Sampling bias

Answer 50

Which are errors we make when taking a sample from a population that move us away from the correct conclusion about that population

Question 51

T test

Answer 51

Statistical test that is used to compare the means from two samples. It does this by dividing the mean of the samples (the signal) by the sample standard deviation (variability). This means that if you have samples with low variability you can be surer that the difference between the sample means is real. The t-test assumes the populations from which the two samples were taken have symmetric bell shaped curves known as normal distribution that is entered around the sample mean and they also have equal variance.

Question 52

Paired t test

Answer 52

Compares two data sets from the same population before and after a treatment/test

Question 53

Unpaired t test

Answer 53

Compares two data sets form two different populations such as male vs females or young vs old

Question 54

P<0.05

Answer 54

Statistically significant

Question 55

P > 0.05

Answer 55

Not statistically significant

Question 56

P100s different from male to female because....

Answer 56

due to endocrine (e.g. hormonal influence on myelin) or anatomical variance between sexes such as in head circumference

Question 57

Are we unconscious when we are asleep?

Answer 57

No because we can be woken up

Question 58

Coma vs vegetative state

Answer 58

The word coma usually refers to the state in which a person appears to be asleep but cannot be awakened. Persistent vegetative state refers to another form of altered consciousness in which the person appears to be awake but does not respond meaningfully to the outside world.

Question 59

Vegetative state - patient exhibit the arousal component of consciousness but not awareness. which part of the brain is most likely malfunctioning in a patient in a vegetative state

Answer 59

if the patient has no awareness, this indicates that the cerebral cortex is malfunctioning

Question 60

Amplitude of alpha rhythm is greater with the eyes...

Answer 60

closed (synchronised activity)