BLOA - techniques used to study the brain

What is a paradigm?

A set of assumptions of what to study about something and how

What are the 3 assumptions of the biological paradigm?

Biological Determinism - behaviour is caused by genetic inheritance and is therefore adaptive

The Nervous System - determines behaviour via neurotransmitters

The Endocrine System - determines behaviour via hormones

What are the 7 techniques used to study the brain?

• Brain Autopsy

• Brain Surgery

• Magnetic Resonance Imaging

• Positron Emission Tomography

• Electroencephalogram

• Computerised Tomogrophy

• functional Magnetic Resonance Imaging

What is a Brain Autopsy?

The surgical exploration of a deceased brain to explore correlations between physiological and behavioural anomalies. The brain is frozen and then sliced to be examined under the microscope. Eg. Broca

Strengths of brain autopsies

High visual resolution, individual neurones can be seen, enabling definite diagnosis of degenerative diseases which can aid future patients

No harm to the individual

Weaknesses of brain autopsies

Issue of consent as the individual must be psychologically sound to give consent

May cause possible distress to families

Cannot show a direct correlation

What is brain surgery?

Surgery on the brain normally undertaken to resolve medical issues rather than for research. patients must remain conscious

Advantages of brain surgery

Enables exploration of localisation of function

It does not rely on secondary images

Weaknesses of brain surgery

Highly invasive Potential risk of brain damage to patient

Only used when scans are not detailed enough to ascertain a problem

What are CT scans?

a 2D x-ray scan of 'slices' of the brain that use a computer to produce a detailed 3D black and white image

Advantages of CT scans

provide high resolution images to identify bleeding in soft brain tissue or fractures in the skull.

relatively cheaper than MRIs

patient can be mobile

Non invasive

no magnetism involved, so can be used on patients with metal implants

Weaknesses of CT Scans

exposure to x-rays can increase risk of cancer only display the structure of brain, function cannot be displayed

What are MRIs?

Use magnets and radio waves to produce a picture of the brain. They can show bleeding, tumours, nerve injury and damage caused by strokes.

They can be used to show changes in the grey matter near the surface of the brain by measuring the number of hydrogen nuclei

Advantages of MRIs

Produce high resolution 3D images

Good for frequent scanning as it does not use any forms of radiation

Can show changes in volume of matter enabling localisation

Weaknesses of MRIs

highly invasive, patient must be stationary not able to use on those with metal inserts very expensive

What is an EEG?

An activity graph that records electrical brain activity using electrodes attached to a person's scalp. It can be used to measure brain activity after an injury or stroke

Advantages of an EEG

one of the cheapest ways to identify brain functions

unaffected by movement

can see activity unfold in real time, to the millisecond

Weaknesses of the EEG

It is difficult to link the function of the brain to a specific area, particularly as it may be emerging from multiple areas

What are PET scans?

A radio-tracer is attached to either oxygen or glucose, so they can be traced when one undertakes a particular activity.

eg. Cancer cells are active in using glucose, so a radio tracers attached to glucose would accumulate near a cancerous tumour

Brain cells affected by alzheimers take up glucose more slowly so this could also be detected using radiotracers

Advantages of PET scans

As they detect biochemical functions, they can detect diseases such as Alzheimer's before change in anatomy becomes apparent

Can be used in conjunction with CTs and MRIs to find biochemical changes in anatomy that has altered.

Can distinguish between benign and malignant tissue

Weaknesses of PET scans

radio tracers, whether injected or ingested, are invasive.

Images are not as clear as fMRIs

Risk of cancer

Expensive

What are fMRIs?

Operates similarly to an MRI but measures oxygenated blood flow in the brain to certain areas.

A coloured, moving 3D image is produced and it is mapped in voxels, each representing thousands of neurons

Advantages of fMRIs

A typical image producing 130,000 voxels means very high resolution enabling correlation between brain activity and cognitive processing.

Can be undertaken simultaneously with an EEG to provide a more holistic picture, studying both the surface and deeper structures in the brain and their interactions.

Weaknesses of fMRIs

Expensive

Temporal resolution is slower than an EEG