Bio - Ways of studying the brain Flashcards

1
Q

What are the 4 ways of studying the brain?

A

Functional magnetic resonance imaging (fMRI)
Electroencephalogram (EEG)
Event-related potentials (ERPs)
Post-mortem examinations

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2
Q

Electroencephalogram (EEG)

A

A method of recording changes in the electrical activity of the brain using electrodes attached to the scalp.

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3
Q

Event-related potentials (ERPs)

A

A technique that takes raw EEG data and uses it to investigate cognitive processing of a specific event. It achieves this by taking multiple readings and averaging them in order to filter out all brain activity that is not related to the appearance of the stimulus.

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4
Q

Functional magnetic resonance imaging (fMRI)

A

A technique for measuring brain activity. It works by detecting changes in blood oxygenation and flow that indicate increased neural activity.

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5
Q

Post-mortem examinations

A

Ways of examining the brains of people who have shown particular psychological abnormalities prior to their death in an attempt to establish possible neurobiological cause for this behaviour.

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6
Q

Explain what happens in fMRI

A

Changes in brain activity are measured while a person performs a task.

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7
Q

What information is obtained from fMRI?

A

As changes in blood flow are measured in particular areas of the brain, increased neural activity can be indicated when a ppt is performing a task.

If a particular area of the brain becomes more active, there is an increased demand for oxygen in that area. The brain responds to this extra demand by increasing blood flow, delivering oxygen in the RBC.

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8
Q

What can researchers do with the information obtained from fMRIs?

A

They are able to produce maps showing which areas of the brain are involved in a particular mental activity.

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9
Q

What do fMRIs measure?

A

Changes in blood flow in/to the brain.

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10
Q

What does an EEG measure?

A

Electrical activity in the brain.

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11
Q

Explain what happens during an EEG

A

Electrodes are placed on the scalp which detect small electrical charges resulting from activity of the brain cells. When electrical signals from the different electrodes are graphed over a period of time, the resulting representation is called an EEG.

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12
Q

What information is obtained from an EEG?

A

Small electrical charges are detected by electrodes placed on the scalp from the activity of brain cells. This information is collected over a period of time to produce an EEG.

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13
Q

What can EEG data be used for?

A

To detect various types of brain disorder (such as epilepsy) or to diagnose other disorders that influence brain activity (such as Alzheimer’s disease).

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14
Q

What would an EEG look like for someone with epilepsy?

A

The EEG readings would show spikes of electrical activity.

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15
Q

What would an EEG look like for someone with brain disease and/or brain injury?

A

The EEG patterns would show overall slowing of electrical activity.

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16
Q

What are the five basic EEG patterns?

A

Gamma waves, beta waves, alpha waves and theta waves.

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17
Q

When would rhythmical alpha waves be recorded by an EEG?

A

When the person is awake but relaxed

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18
Q

When would beta waves be recorded by an EEG?

A

When the person is physiologically aroused, their EEG pattern shows low amplitude and fast frequency beta waves. (Excited/anxious)

Beta waves are also found in REM sleep when the eyes move rapidly back and forth.

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19
Q

When would delta waves be recorded by an EEG?

A

During deep sleep (when repair happens) (glymphatic cycle/dreamless) (NOT WHEN CONSCIOUS).

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20
Q

When would theta waves be recorded by an EEG?

A

During light sleep/dreaming/deep meditation.

21
Q

When would gamma waves be recorded by an EEG?

A

When a person is alert, learning, problem-solving, etc.

22
Q

What type of waves would be recorded by an EEG when a person is awake but relaxed?

A

Alpha.

23
Q

What type of waves would be recorded by an EEG when a person is physiologically aroused or is in REM sleep?

A

Beta.

24
Q

What type of waves would be recorded by an EEG when a person is in deep sleep (NOT WHEN CONSCIOUS)?

A

Delta.

25
Q

What type of waves would be recorded by an EEG when a person is in light sleep/dreaming/deep meditation?

A

Theta.

26
Q

What type of waves would be recorded by an EEG when a person is alert, learning, problem-solving, etc?

A

Gamma.

27
Q

What can be seen from an EEG when a person moves from light to deep sleep?

A

The occurrence of alpha waves decreases and are replaced first by lower frequency theta waves and then by delta waves.

28
Q

Explain what ERPs are

A

Very small voltage changes in the brain that are triggered by specific events or stimuli, such as cognitive processing of a specific stimulus.

29
Q

Because ERPs are difficult to pick out from all the other electrical activity being generated within the brain at a given time, what can be done to establish a specific response to a target stimulus?

A

Many presentations of the stimulus have to be carried out and these responses are then averaged together.

30
Q

Why is it valid when measuring ERPs to average out the responses found to establish a specific response to a target stimulus?

A

Because any extraneous neural activity that is not related to the specific stimulus will not occur consistently, whereas activity linked to the stimulus will.

This has the effect of cancelling out the background neural ‘noise’, making the specific response to the stimulus in question stand out more clearly.

31
Q

What 2 categories can ERPs be divided into?

A

Sensory ERPs and cognitive ERPs.

32
Q

What are sensory ERPs?

A

Waves occurring within the first 100ms after presentation of the stimulus.

33
Q

Why are waves occurring within the first 100ms after presentation of the stimulus termed sensory ERPs?

A

As they reflect an initial response to the physical characteristics of the stimulus (detecting).

34
Q

What are cognitive ERPs?

A

Waves generated after 100ms from when the stimulus was presented.

35
Q

Why are waves occurring more than 100ms after presentation of the stimulus termed cognitive ERPs?

A

As they reflect the manner in which the subject evaluates the stimulus and demonstrate information processing (interpreting).

36
Q

What happens in the process of finding ERPs?

A
  • An EEG machine is used.
  • A patient repeats an action many times.
  • We record ‘normal’ baseline readings.
  • We can infer what electrical activity was due to the repeated action/activity (correlation).
37
Q

Explain how fMRIs are able to produce information about blood flow

A
  • A ppt performs tasks inside an electromagnetic tunnel.
  • A magnetic field aligns hydrogen nuclei (abundant in blood/haemoglobin(hB)).
  • Radio pulse ‘flips’ nuclei, then when they realign, they release energy.
  • Energy differences (gradients) are mapped using a coil.
  • These are mapped onto a computer-generated frame to produce images.
  • Brighter areas have more blood flow (they’re doing more work).
38
Q

What is the mapping technique used in fMRIs called?

A

BOLD - Blood Oxygenation Level Dependent activity.

39
Q

What does BOLD stand for in relation to fMRIs?

A

BOLD - Blood Oxygenation Level Dependent activity.

40
Q

Give examples of how post-mortem examinations have been used to provide evidence for the functions of certain brain areas

A

Broca’s patient Tan, who displayed speech problems when alive was subsequently found to have a lesion in the area of the brain that is now known as ‘Broca’s area’ which is an important are for speech production.

Annese et al. (2014) confirmed that HM’s inability to store new memories was linked to lesions in the hippocampus.

Cotter et al. (2001) found evidence of reduced numbers of glial cells in the (pre)frontal cortex of patients with depression. Therefore, a link has been established between psychiatric disorders, such as schizophrenia and depression, and underlying brain abnormalities.

41
Q

What are the strengths of fMRI?

A
  • Non-invasive (i.e. does not involve the insertion of instruments into the body), nor does it expose the brain to potentially harmful radiation unlike other scanning techniques.
  • Offers a more objective and reliable measure of psychological processes than is possible with verbal reports. It is a useful way of investigating psychological phenomena that people would not be capable of providing in verbal reports.
42
Q

What are the limitations of fMRI?

A
  • Because it measures changes in blood flow in the brain, it is not a direct measure of neural activity in particular brain areas. This means it is not a truly quantitative measure of mental activity in these brain areas.
  • Critics argue that fMRI overlooks the networked nature of brain activity, as it focuses only on localised activity in the brain. They claim that it is communication among the different regions that is most critical to mental function and this can’t be seen on fMRI yet (Connectome project).
  • Correlational data only (third variable problem).
43
Q

What are the strengths of EEG?

A
  • Provides a recording of the brain’s activity in real time rather than a still image of the passive brain. This means that the researcher can accurately measure a particular task or activity associated with it.
  • Useful in clinical diagnosis, e.g. by recording the abnormal neural activity associated with epilepsy. Epileptic seizures are caused by disturbed brain activity, which means that the normal EEG reading suddenly changes. This helps diagnose whether some experiencing seizures has epilepsy.
  • Low-cost option for research.
44
Q

What are the limitations of EEG?

A
  • Can only detect the activity in superficial regions of the brain so it cannot reveal what is going on in deeper regions such as the hypothalamus or hippocampus. Electrodes can be implanted in non-humans to achieve this, but it is not ethically permissible to do this with humans because this would be too invasive.
  • Electrical activity can be picked up by several neighbouring electrodes, therefore the EEG signal is not useful for pinpointing the exact source of an activity. As a result, it doesn’t allow researchers to distinguish between activities originating in different but closely adjacent locations in the brain. (Not very sensitive).
  • Correlational data only (third variable problem).
45
Q

What are the strengths of ERPs?

A
  • They provide a continuous measure of processing in response to a particular stimulus which make it possible to determine how processing is affected by a specific experimental manipulation, for example during presentation of different visual stimuli.
  • An ERP can measure the processing of the stimuli even in the absence of a behavioural response. ERP recordings make it possible to monitor ‘covertly’ the processing of a particular stimulus without requiring the person to respond to them (we can tell when someone is thinking).
46
Q

What are the limitations of ERPs?

A
  • Correlational data only (third variable problem).
  • ERPs are so small and difficult to pick out from other electrical activity in the brain so it requires a large number of trials to gain meaningful data. This places limitations on the types of questions that ERP readings can realistically answer. A large number of trials also means that it is time consuming and expensive.
  • Only sufficiently strong voltage changes generated across the scalp are recordable. Important electrical activities occurring deep in the brain are not recorded, meaning that the generation of ERPs tends to be restricted to the neocortex (only useful for neocortical measurements).
47
Q

What are the strengths of post-mortem examinations?

A
  • Allow for a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible with the sole use of non-invasive scanning techniques such as fMRI and EEG. For example, it enables the researchers to examine deeper regions of the brain such as the hypothalamus and hippocampus.
  • Harrison (2000) claims that post-mortem studies have played a central part in our understanding of the origins of schizophrenia. He suggests that as a direct result of post-mortem examinations, researchers have discovered structural abnormalities of the brain and found evidence in changes in neurotransmitter systems, both of which are associated with the disorder. (Application.)
  • All regions of the brain are available for study.
48
Q

What are the limitations of post-mortem examinations?

A
  • Because people die in a variety of circumstances and at varying stage of disease, these factors can influence the post-mortem brain. Similarly, the length of time between death and the post-mortem (post-mortem delay), degradation of brain tissue, diseases, drug treatments and age at death/age of brain are possible confounding influences of any difference between cases and controls.
  • This approach is limited because it is retrospective as the person is already dead. As a result, the researcher is unable to follow up on anything that arises from the post-mortem concerning a possible relationship between brain abnormalities and cognitive function. (A snapshot only - the person is dead so we can’t follow up or ask for history.)
  • Correlational data only - can never be tested.