Ways of studying the brain Flashcards
What are post-mortems
Method of investigating the brain after death
Any damage found allows us to link that part of the brain to a particular function
What are PET scans
They allow us to see activity in the brain
Person is injected with radioactive glucose
The scans detect metabolism of substance and shows us which parts of the brain are most active during a period
What are MRI scans
Allow us to investigate the structure of the brain
Strong magnetic waves are sent through the body
hydrogen atoms are forced into a different position so the boy sends radio waves of its own which are detected by the scanner
What are fMRI scans
Allow us to observe and measure brain function
It detects blood oxygenation to each area of the brain(more active areas require more oxygen). This is called the BOLD signal.
What are EEGs
Electrodes are placed on the surface of the skull
They measure changes in electrical activity when a person performs a specified task
They record activity from groups of neurons in the brain but it is a crude measurement shown in waves
Type of waves indicate the parts of the brain performing the task
What are ERPs
Ps undergo multiple EEGs and are presented with a specific stimulus multiple times
The signals are averaged out so extraneous signals diminish and the signal related to the event remains
By removing the background noise of general brain activity, researchers can see which electrical activity occurred in response to the event
Strengths of Post-mortems(at least 2)
- PM evidence was vital in providing a foundation for early understanding of key processes in the brain
- Both Broca and Wernicke relied on PM studies in establishing links between language, brain and behaviour decades before neuroimaging began
- PM studies improved medical knowledge and helps generate hypotheses for further studies
Weaknesses of Post-mortems(at least 2)
- PM evidence was vital in providing a foundation for early understanding of key processes in the brain
- Both Broca and Wernicke relied on PM studies in establishing links between language, brain and behaviour decades before neuroimaging began
- PM studies improved medical knowledge and helps generate hypotheses for further studies
Strengths of fMRIs(at least 2)
- High spatial resolution so you can see finer details
No radiation and non-invasive so fewer risks
Weaknesses of fMRIs(at least 2)
- Low temporal resolution(5 second time lag)
- More expensive
- Patient must be completely still so limited range of stimuli/responses can be measured(sleep, hallucinations etc). Not always possible to replicate some activity in the scanner
Strengths of EEGs(at least 2)
- EEGs are important in the diagnosis of conditions such as epilepsy, a disorder characterised by random burst of activity in the brain that can be easily detected
- Similarly, it has contributed much to our understanding of the stages involved in sleep
- Unlike fMRI, EEG technology has extremely high temporal resolution
- Todays, EEG technology can accurately detect brain activity at a resolution of one millisecond
Weaknesses of EEGs(at least 2)
- EEGs tend to produce very generalised information so it is not useful for pinpointing the exact source of neural activity
- EEGs do not allow researchers to distinguish between activity originating in different but adjacent locations of the brain
Strengths of ERPs(at least 2)
- ERPs partly address the limitations of EEG
- ERPs bring much more specificity to the measurement of neural processes than could be achieved using raw EEG data
- As ERPs are derived from EEG measurements, they have excellent temporal resolution, especially when compared to fMRIs
- The excellent temporal resolution ERPs have led to their widespread use in the measurement of cognitive functions and deficits
- Researchers have been able to identify many different types of ERP and describe the precise role of these in cognitive functioning including parts of working memory
Weaknesses: - Critics have pointed to a lack of standardisation in ERP methodology between different research studies, making it difficult to confirm findings
- A further issue is that, in order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated, which is not always easy to do
Weaknesses of ERPs(at least 2)
- Critics have pointed to a lack of standardisation in ERP methodology between different research studies, making it difficult to confirm findings
- A further issue is that, in order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated, which is not always easy to do
Strengths of MRI scans(at least 2)
- No ionizing radiation: Unlike X-rays or CT scans, MRIs do not expose patients to harmful radiation.
- Excellent soft tissue contrast: They provide detailed images of soft tissues, making them ideal for detecting brain tumours, ligament injuries, and organ abnormalities.
- Non-invasive and painless: The procedure does not require surgery and is generally well tolerated.
- Effective for blood flow analysis: MRIs can track blood movement, helping diagnose vascular conditions.
- Versatile imaging: They can scan various body parts in multiple directions, offering comprehensive diagnostic capabilities.
Weaknesses of MRI scans(at least 2)
- Expensive: MRI machines and procedures are costly compared to other imaging techniques.
- Claustrophobia risk: Some patients find the enclosed space uncomfortable, which may require sedation.
- Requires stillness: Movement during the scan can blur images, making it challenging for infants or restless patients.
- Magnetic field hazards: The strong magnetic field can attract metal objects, posing safety risks.
- Contrast agent risks: Some patients may experience allergic reactions to contrast agents used in certain MRI scans.
Strengths of PET scans(at least 2)
- Excellent for functional imaging: Unlike MRI or CT scans, PET scans show metabolic activity, helping detect diseases at an early stage.
- Useful in cancer detection: PET scans can identify cancerous cells based on their glucose uptake, making them valuable for diagnosis and monitoring treatment.
- Effective for brain disorders: They help assess conditions like Alzheimer’s disease by mapping changes in brain metabolism.
- Can track disease progression: PET scans allow for repeated imaging to monitor how a disease evolves over time.
Combines with CT or MRI: Hybrid PET-CT or PET-MRI scans provide both anatomical and functional details for more precise diagnosis
Weaknesses of PET scans(at least 2)
- Exposure to radiation: PET scans use radioactive tracers, which, while generally safe, involve some radiation exposure.
- Expensive and limited availability: PET scanners are costly, and not all medical facilities have them.
- Short half-life of tracers: The radioactive material used in PET scans decays quickly, requiring rapid imaging and specialized facilities.
- Lower spatial resolution: Compared to MRI and CT, PET scans are less detailed in anatomical imaging.
Lengthy procedure: The scan and preparation (including waiting for tracer absorption) can take time, making it less convenient for quick diagnoses.
