The purpose and function of magnetic resonance imaging (MRI) and functional MRI (fMRI)

Magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI) are scanning techniques that utilise magnetic fields and radio waves to explore the brain's structure and activity. MRI creates detailed images of the brain, while fMRI looks at blood flow to detect areas of activity associated with specific behaviors.

Key features of MRI and fMRI

• MRI overview - Produces detailed images of the brain's anatomy.
• fMRI overview - Measures blood flow changes in the brain to pinpoint areas of activity linked to specific tasks or behaviours.
• Non-invasive nature - Both techniques avoid the need for surgery or radiation.
• Research insights - Szycik et al. (2017) used fMRI scanning to find no differences between brain activation patterns of violent and non-violent computer game players when viewing emotionally sensitive pictures.

The role of computerised axial tomography (CAT) scans in brain imaging

Computerised axial tomography (CAT) scans provide a still picture of the physiology of the brain using X-rays. Images are merged to form a 3D picture of the brain.

Characteristics of CAT scans

• Static imaging - Creates a three-dimensional picture of the brain.
• Accessibility - Equipment is widely available and relatively cost-effective.
• Research application - Wei et al. (2015) reviewed CAT scans of over 5,500 depressive patients, finding a relationship between right-hemisphere strokes and depression, but not between left-hemisphere strokes and depression.

The application of positron emission tomography (PET) scans for brain activity

Positron emission tomography (PET) scans show which brain areas are involved in specific behaviours by creating dynamic images of levels of radioactivity in the brain after injecting radioactive fluorodeoxyglucose into the bloodstream.

Features of PET scans

• Dynamic imaging - After injecting a radioactive tracer like fluorodeoxyglucose, PET scans capture changes in brain activity associated with specific behaviours.
• Behavioural insights - Reveals which brain areas are active during tasks.
• Research findings - Azari et al. (2001) used PET scans to find that religious participants, when reciting psalms, activated brain circuits permitting meditative states, which did not occur in non-religious participants.

The use of electroencephalography (EEG) in monitoring brain function

Electroencephalography (EEG) gives an overall picture of activity within the brain. Electrodes attached to the scalp record electrical events in the brain to monitor specific behaviours by comparing different levels of electrical signal.

Aspects of EEG technology

• Electrical monitoring - Captures brain wave patterns to assess activity levels.
• Non-invasive approach - Poses minimal risk as it involves no radiation or confined spaces.
• Environmental influence - Aspinall et al. (2015) found different levels of brain arousal associated with people walking around different environments of Edinburgh.
• Sleep studies - Particularly effective in identifying different stages of sleep.

Evaluations and practical applications of brain scanning techniques

Brain scanning techniques have transformed neuroscience by offering insights into brain structure and function. However, each method comes with strengths and limitations.

Strengths of brain scanning methods

• CAT scan accessibility - Due to availability of equipment and relatively cheap cost, CAT scans allow large numbers of brains to be scanned, making results more valid.
• PET scan dynamics - As PET scans are dynamic, they allow brain activation changes associated with specific behaviours to be detected.
• fMRI detail - fMRI scans give great amounts of detail, as they provide moving pictures, informing about patterns of activation and localization of function.
• EEG safety - EEG usage has been useful in studying different stages of sleep, and being non-invasive carries minimal risks of harm.

Scanning techniques have identified specific brain areas associated with mental disorders, allowing therapies to be more targeted.

Limitations of brain scanning methods

• fMRI data concerns - Stelzer et al. (2014) highlighted issues with the way fMRI data is analysed, leading to publication of false results.
• CAT scan constraints - As CAT scans take static pictures, they can identify structural damage in individual brains, but cannot localize activity in typical brains.
• MRI/fMRI discomfort - The tight space involved in MRI/fMRI scanning can be uncomfortable, causing distress, which with fMRI scans can produce unreliable readings.
• PET scan drawbacks - PET scans are relatively expensive, limiting their usage, and as radiation is involved, they incur health risks.

Ethical considerations in brain scanning

Patients need to be aware of procedures and risks to be able to give fully informed consent.