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neurophysiology > Lab 1 > Flashcards

Lab 1 Flashcards

1
Q

Normal EEG tracing

A

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

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2
Q

Alpha rhythm

A

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.

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3
Q

Beta rhythm

A

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.

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4
Q

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

A

8-12 Hz

Larger amplitudes than beta

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5
Q

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

A

13-30 Hz

Smaller amplitudes than alpha

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6
Q

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

A

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

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7
Q

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

A

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

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8
Q

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

A

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

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9
Q

Cortical evoked potential

A

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

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10
Q

Alpha vs Beta rhythm

A

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

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11
Q

Frequency of alpha rhythm

A

8-12 Hz

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12
Q

Frequency of beta rhythm

A

13-30 Hz

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13
Q

Visual evoked potential

A

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.

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14
Q

Visual evoked potential

A

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.

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15
Q

Biological data measurement

A

Input - amplification - filtering - sampling - display

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

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16
Q

The overall idea of digital biological recording

A

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.

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17
Q

Scope mode

A

Used to record very rapid events over short periods

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18
Q

Chart mode

A

used for recording continuous events

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19
Q

Sampling rate

A

A correct sampling rate is essential to recording good quality data

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20
Q

Importance of the correct sampling rate for the finger transducer experiment

A

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

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21
Q

High sampling rate

A

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

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22
Q

Low sampling rate

A

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

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23
Q

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

A

1k/s

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24
Q

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

A

Breathing

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25
Q

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

A

It decreases the amplitude therefore the pulse gets weaker

26
Q

Overall idea of sample rate

A

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

27
Q

Frequency

A

1/duration

28
Q

Electrical waveform of the EEG depends on our …

A

State of consciousness

29
Q

EEGs are recorded by

A

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

30
Q

Noise artifacts in EEG

A

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

31
Q

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

A

Movement will generate electrical noise from muscle activation

32
Q

Synchronised activity in an EEG recording trace

A
  • 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’
33
Q

Desynchronised activity in an EEG recording trace

A 
• 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’
34
Q

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

A

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

35
Q

Synchronised activity eyes open or closed

A

Eyes closed

36
Q

Desynchronised activity eyes open or closed

A

Eyes open

37
Q

Alpha waves for synchronised activity

A

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

38
Q

Alpha waves for desynchronised activity

A

No prominent peaks

39
Q

If EPSPs summate for synchronised activity then …

A

Will get a bigger alpha between 8-12 Hz

40
Q

VEP

A

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

41
Q

VEP form

A

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

42
Q

P100 VEP

A

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

43
Q

Small early peak and small late peak VEP

A

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

44
Q

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

A

Phototransduction, signal transmission, synapses

45
Q

CEP

A

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

46
Q

Latency

A

The time delay between a stimulus and a response

47
Q

Slow wave form peak than P100 would indicate…

A

Slower would means demyelination, slower reaction times etc

48
Q

Sample mean

A

Which represents our best guess at the mean from the population

49
Q

Sample standard deviation

A

Which gives an estimate of sampling precision/variance

measure of how spread out the numbers are

50
Q

Sampling bias

A

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

51
Q

T test

A

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.

52
Q

Paired t test

A

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

53
Q

Unpaired t test

A

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

54
Q

P<0.05

A

Statistically significant

55
Q

P > 0.05

A

Not statistically significant

56
Q

P100s different from male to female because….

A

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

57
Q

Are we unconscious when we are asleep?

A

No because we can be woken up

58
Q

Coma vs vegetative state

A

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.

59
Q

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

A

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

60
Q

Amplitude of alpha rhythm is greater with the eyes…

A

closed (synchronised activity)

neurophysiology (29 decks)

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