MRI and fMRI

Magnetic Resonance Imaging (MRI)

• Utilizes a large magnet and radio waves to produce images of brain structures.
• Pinpoints specific brain structures that may be damaged or have increased grey matter.
• Identifies links between brain and behavior.
• Identifies blood circulation problems by showing blood flow in the brain.
• Creates high-resolution brain images.
• Considered non-invasive
• Susceptible to disturbances from noise, temperature, and calibration errors, affecting reliability.
• Can be expensive.
• Is affected by patients movement while scanning
• Does not show a cause-and-effect relationship.
• Shows brain structure but not activity.

Functional Magnetic Resonance Imaging (fMRI)

• Measures oxygenated blood flow in the brain to indicate brain activity.
• Measures oxygenated blood in specific brain regions.
• Brain activity can be linked to cognitive processes, such as emotion.
• Does not use radioactive substances.
• Records activity in all parts of the brain.
• Has a 5-second delay between brain activity and measurement, which may miss important information.
• Focuses on localization of brain function and does not consider neuroplasticity.
• Shows no cause-and-effect relationship

General Evaluation of Brain Imaging Techniques

• The unnatural environment may affect findings.
• Colors can exaggerate effects on the brain.
• Brain images are compilations taken over time.
• Scanning is relatively more ethical.
• Researchers use images, creating better triangulation

Positron Emission Tomography (PET)

• Uses a radioactive tracer to measure glucose metabolism in the brain.
• Can highlight abnormalities and illnesses more effectively than other scanning techniques.
• Involves some risk to the patient due to the use of a radioactive tracer.

Computerized Axial Tomography (CAT)

• It is a noninvasive diagnostic imaging procedure that uses X-rays to produce images of the brain.
• Provides detailed information about brain tissue and structures.
• CT scans are fast, making them ideal in emergency situations like stroke, trauma, or head injury.
• Good for visualizing bone fractures and detecting acute intracranial hemorrhages.
• More accessible than MRI, especially in smaller or rural hospitals.
• Less expensive than MRI.
• Involves ionizing radiation, which adds cumulative risk, especially concerning children or repeated scans.
• Not as good as MRI in showing detailed images of soft tissues like the brainstem, spinal cord, or small tumors.
• May miss early signs of stroke within the first few hours of onset (MRI is more sensitive in this case).
• In rare cases, contrast-enhanced CT can trigger allergic reactions or affect kidney function.

Electroencephalogram (EEG)

• Detects abnormalities in brain waves.
• Electrodes are pasted onto the scalp to detect brain cells activity.
• Excellent for detecting real-time brain activity.
• Shows brain activity on a millisecond scale.
• Highly effective for diagnosing conditions like epilepsy, seizure disorders, and monitoring brain function during anesthesia or sleep studies.
• Cannot precisely localize abnormal activity deep within the brain.

Maguire et al. (2000) - MRI

• Aimed to investigate spatial navigation in London black cab taxi drivers using MRI.
• Participants included 16 healthy, right-handed male London black cab taxi drivers aged 32-62.
• MRI measured the volume of grey matter in the hippocampus.
• Taxi drivers showed a greater volume of grey matter in their posterior hippocampi compared to the control group.
• A positive correlation was found between the volume of posterior hippocampal grey matter and time spent as a taxi driver.
• The posterior hippocampus may be linked to spatial navigation skills.
• Highly controlled clinical method obtained objective data for easy comparison and analysis.
• A researcher blind to the conditions counted the pixels on the MRI images, increasing internal validity.
• A correlation cannot show cause-and-effect, so it is impossible to know whether the taxi drivers already had naturally high levels of hippocampal grey matter.
• Only generalizable to male, right-handed London taxi drivers.

Luby et al. (2013) - MRI

• Aimed to investigate whether poverty experienced in childhood is shown in delayed brain development using MRI.
• Participants included145 right-handed children from the USA, categorized as living in poverty.
• Children underwent regular testing to measure cognitive, emotional, and social skills.
• Data was collected on the children's closeness to caregivers and stressful events in their lives.
• Children had two MRI scans of the whole brain or just the hippocampus and amygdala.
• Both the hippocampus and the amygdala showed less white and grey matter in the MRI scans.
• Positive care from adults had a less negative effect on the hippocampus, while stressful life events affected the left hippocampus.
• Poverty appears to have a negative effect on brain development in childhood.
• Behavioral, cognitive, and social measures were checked against MRI results, increasing internal validity.
• Longitudinal design allowed for real changes and comparisons across time.
• The MRI scans may have picked up differences in the brains of the children which were not the result of poverty.
• Difficult to generalize since sample only represents pre-school children living in poverty with depression symptoms.

Fisher et al. (2005) - fMRI

• Aimed to investigate the brain systems involved in early-stage intense romantic love.
• Participants included 10 females and 7 males aged 18-26 who reported being 'in love'.
• Participants were shown a photograph of their loved one, followed by a distraction task, then a neutral photograph.
• When viewing the photograph of their loved one, the right ventral tegmental area and the right caudate nucleus were active.
• These areas are associated with dopamine activation.
• People in the early stages of romantic love access areas of the brain associated with motivation and reward.
• Human beings may have evolved a brain system which ensures that they become addicted to love which increases the study’s validity.
• The use of a standardised procedure means that the study is replicable, which increases its reliability.
• Small sample size of 17 participants means that the results are not very meaningful and may not be robust in terms of statistical analysis.
• The idea that romantic love that can be measured via fMRI is overly reductionist.

Raine et al. (1997) - PET

• Aimed to investigate differences in the brains of impulsive murderers compared to non-murderers.
• Participants included 41 murderers who had pleaded NGRI (not guilty by reason of insanity).
• A matched pairs design was used with a control group of non-murderers.
• Participants were injected with a radioactive tracer and completed cognitive tasks while undergoing a PET scan.
• Impulsive murderers showed less activity in the prefrontal cortex (PFC).
• Murderers also showed asymmetrical activity in the amygdala.
• Brain dysfunction may mean that someone is more prone to violent outbursts.
• The use of a matched pairs design means that individual differences could to some extent be controlled for
• This use of a purposive sample of NGRI murderers increases the validity of the study as the participants had all experienced a lack of control which led to violent behaviour thus they may all share similar features of brain function
• The results of this study may lead to a deterministic bias against offenders guilty of impulsive murder.
• This is an example of a snapshot design: it cannot tell us anything about behaviour across time

Wei et al. (2015) - CAT Scan

• Aim was to determine whether the location of brain damage (via stroke) influences the risk of developing post-stroke depression.
• A meta-analysis reviewed data from studies using CAT scans on 5,507 stroke patients.
• Stroke damage was categorized by hemisphere (right vs. left).
• Patients with right hemisphere strokes had a higher risk of depression.
• Structural damage in certain brain regions is linked to psychological outcomes.
• Large sample sizes from multiple studies gave high statistical power and confidence in the findings.
• Researchers focused on physiological underpinnings of mental health, providing biological insight into post-stroke depression.
• CAT scans do not show brain activity, only structure.
• Meta-analysis may involve variation in data quality and methodology across different studies.

Aspinall et al. (2015) - EEG Scan

• Aimed to explore how different urban environments impact real-time brain activity using mobile EEG technology.
• Participants were fitted with mobile EEG headsets and walked through a busy urban shopping street, a green path in a park, and a crowded commercial district.
• Urban settings showed increased engagement and arousal.
• Green space walks resulted in higher levels of meditative brain activity and reduced frustration.
• Environmental context directly affects brain activity and mood.
• Exposure to natural green environments can reduce stress and promote well-being.
• High ecological validity as mobile EEGs allowed brain activity to be measured in real-life conditions.
• Showed a clear link between environment and mental state.
• Innovative use of technology not possible with fMRI or CAT in mobile settings.
• Lower spatial resolution of mobile EEGs compared to fMRI.

Evaluation of Brain Imaging Techniques

• EEG is non-invasive and relatively low-cost (around $200) .
• It has high temporal resolution, detecting brain activity changes within milliseconds.
• Lacks spatial precision, offering limited localization of brain activity.
• CAT provides high-resolution static images of brain structure.
• Good for identifying physical abnormalities such as tumors or damage.
• Involves exposure to radiation.
• Relatively affordable (approximately $271) and widely available.
• PET allows for dynamic imaging and localization of brain activity during tasks.
• Good for studying functional processes in the brain.
• PET scans are slow in temporal resolution and costly (about $1266).