Biopsychology: Ways Of Studing The Brain Flashcards
Outline Functional Resonance Imaging.
> A brain scanning technique that measures blood flow in the brain when a person performs a task.
FMRI works on the premise that neurons in the brain that are most active during a task use the most energy. Energy requires glucose and oxygen.
Oxygen is carried in the bloodstream attached to heemoglobin and is released for use by these active neurons at which point haemoglobin becomes deoxygenated.
Deoxygenated haemoglobin has a different magnetic quality from oxygenated haemoglobin.
A FMRI can detect these different magnetic qualities and can be used to create a dynamic 3D map of the brain, highlighting which areas are involved in different neural activities.
Outline Post-Morton Examination.
> A method of investigating the brain where researchers will study the brains of people who have died.
It involves studying the brains of deceased people who presented with unusual mental or behavioural conditions.
They can compare the brains of these people with more neurotypical brains, and so potentially identify the functions of brain regions.
E.g Broca examined the brain of a man who displayed speech problems when he was alive. It was subsequently discovered that he has a lesion in the area of the brain important for speech production. This is known as Broca’s area.
Outline Electroencephalogram.
> Works on the premise that information is processed in the brain as electrical activity in the form of nerve impulses, transmitted along neurons.
EEG scanners measure this electrical activity through electrodes attached to the scalp. Small electrical charged detected by the electrodes are graphed over a period of time, indicating the level of activity in the brain.
EEG scanning was responsible for developing our understanding for REM sleep, which is associated with a fast, and seemingly chaotic activity in the brain.
This activity closely resembles the waking brain and is indicative of dreaming.
Outline Event-related Potentials.
> Electrodes are attached to the scalp and are used the measure the level of electrical activity in the brain.
Unlike EEGs, ERP research involves a stimulus being presented to a participant and the researcher looks for which areas of the brain are active.
Activity would suggest the relevant brain regions play a functional role in the activity connected with the stimulus.
It is difficult to detect the subtle changes in the braun activity when the brain responds to a stimulus.
To solve this issue participants are presented with the stimulus many times and an average response is graphed. This is called averaging, it reduces any extraneous neural activity which makes the specific response to the stimulus stand out.
What is one limitation of post-mortem examination?
The issue of causation. In post-mortem examinations, the researcher study’s the brains of people with unusual behaviours, with the hope of also finding an abnormality in the brain that might explain their behaviour. However, correlation does not equal causation. Brain abnormalities detected after death might have
been the cause of unusual behavior, but there are other explanations. For example, a third variable (e.g., another illness relating to another brain region) might explain the association. Unlike brain scanning techniques (e.g., fMRI, EEG and ERP), post-mortem examinations cannot study a live brain, so it is
especially problematic to attribute causation.
What is a strength of post-mortem examinations?
They provide a detailed examination of the brain. Post-mortem examinations can access areas like the hypothalamus and hippocampus, which other scanning techniques (e.g. EEG, ERP and fMRI) cannot easily access without losing spatial resolution. Post-mortem examinations therefore provide researchers with a tool for forming a detailed picture of all areas of the brain. This is a major advantage compared to current brain scanning techniques.
What is a strength of FMRI as a way of investigating the brain?
They have good spatial resolution. Spatial resolution refers to the smallest feature (or measurement) that a scanner can detect. fMRI scans have a spatial resolution of approximately 1-2 mm. The spatial resolution of fMRI is significantly greater than the other techniques (EEG, ERP, etc.).
Consequently, psychologists can determine the activity of different brain regions with greater accuracy
when using fMRI, in comparison to when using EEG and/or ERP. This means, research using fMRI can specify an exact place in the brain that is active during a particular behaviour.
What is a limitation of FMRI as a way of investigating the brain ?
It’s poor temporal resolution. Temporal resolution refers to how quickly the scanner can detect changes in brain activity. fMRI scans have a temporal resolution of 1-4 seconds. The temporal resolution of fMRI is worse than other techniques (e.g. EEG/ERP which have a
temporal resolution of 1-10 milliseconds). Consequently, psychologists are unable to predict with a high degree of accuracy the onset of brain activity.
What is a strength of the EEG and ERP techniques as a way of investigating the brain?
They have good temporal resolution. Temporal resolution refers to how quickly the scanner can detect changes in brain activity. The EEG/ERP technique takes readings of the brain every millisecond. This means the EEG and ERP techniques record the brain’s activity in real time, and are therefore
much faster at detecting brain activity than other scanning techniques, like fMRI. This leads to an accurate measurement of electrical activity when undertaking a specific task (e.g., sleep with EEG or responding to a visual stimuli with ERP).
What is a limitation of the EEG and ERP techniques as a way of investigating the brain?
They have poor spatial resolution. Spatial resolution refers to the smallest feature (or measurement) that a scanner can detect.
EEGs/ERPs have a spatial resolution of roughly 30 cm. Compared to the spatial resolutions of other scanning techniques, the EEG/ERP technique is extremely low (e.g., fMRI has a spatial resolution of 1-2 mm). Consequently, EEGs/ERPs can only detect
activity in broad regions of the brain, meaning it cannot pinpoint the exact location of neural activity.
