methods of investigating brain function Flashcards
what is an EEG?
- used when we want to investigate the whole brain
- Electrical activity on the scalp from millions of neurons is detected and amplified to produce a continuous picture of activity in the brain over a time period
- Uses small, metal discs called electrodes attached to your scalp
define wave frequency
number of waves that pass a given point in a given time period
define wave amplitude
the magnitude of a reaction or of a stimulus
what are the positives for an EEG?
- Anyone can participate
- Cheap
- Non invasive
- Range of activities
- Very high temporal resolution
- Can detect fast changes
what are the negatives of an EEG?
- Must be connected to computer
- Electrical fields are mostly blocked by skull, can’t measure deep activity
- Sign is weak and spatial resolution is poor
- Don’t show specific area of activity
define functional imaging
study of human brain function based on analysis of data using brain imaging modalities
define temporal resolution
the accuracy of the scanner in relation to time
define spatial resolution
the smallest feature that a scanner can detect
what is the EEG used for?
- Diagnose seizures, strokes, epilepsy, brain injuring and tumors
- Sleep studies
- Confirm brain dead
what is an MRI?
MAGNETIC RESONANCE IMAGING
- STATIC imaging
- Magnetic fields and radio waves are rotated around the head
- Powerful magnet affects nuclei of atoms
- The waves are tuned to the hydrogen in water and energy released from the hydrogen atom is measured to produce a 3D image
- It also distinguishes between different types of soft tissue
what are the uses of an MRI?
- Creates high definition 3D image of brain or body
- Very useful for measuring the size of brain structures
what are the positives of MRI?
- Gives detailed knowledge of brain
- Non invasive
- No radiation
- Patient is conscious and awake
what are the negatives of an MRI?
- Expensive and time-consuming
- Claustrophobic > may cause anxiety
- Image needs to be seen by an expert
- Noisy
- Doesn’t show change in brain over time
what are the negatives of an MRI?
- Expensive and time-consuming
- Claustrophobic > may cause anxiety
- Image needs to be seen by an expert
- Noisy
- Doesn’t show change in brain over time
what is a PET scan?
POSITRON EMISSION TOMOGRAPHY
- DYNAMIC imaging
- Use a radioactive glucose to determine the location of greatest brain activity during a tsk
- Detects the rate of metabolism of injected substances such as radioactive glucose
- Records activity over minutes = scan every 40 seconds
what are the uses of PET scans?
- Provides image of brain biochemical processes
- Detects diseases like strokes, tumors, and dementia
what are the positives of PET scans?
- Person is conscious, can be doing tasks
- Detects active areas of the brain, not just simple images
what are the negatives of PET scan?
- Doesn’t show how healthy the brain is
- Can’t see the damage
- Expensive and time consuming
- Invasive (Radioactive dye)
- Expert must-read scan
what is an FMRI?
FUNCTIONAL MAGNETIC RESONANCE IMAGING
- DYNAMIC imaging
- Shows which brain areas are active when performing a task
- Blood flow changed are also detected by a scanner using a powerful magnet and radio waves
- Compares blood flow between 2 parts
- Scanner is turned to iron in haemoglobin
what is an FMRI used for?
- Detects amount of oxygen in blood
- Detects tumours and other diagnostics
what are the positives of an FMRI?
- Detail 3D image while functioning
- Precise info over time
- Same strengths as MRI
what are the negatives of an FMRI?
- Cause anxiety
- Loud
- Time consuming
- Expensive
what is a CT scan?
COMPUTERISED TOMOGRAPHY
- STATIC imaging
- Type of x-ray, scans the brain at different angles
- Information is fed to computer leading to cross-sectional pictures of slices through the brain
what are the uses of a CT scan?
- Aids in detecting tumours and strokes
- Shows possible abnormalities in brain structures associated with mental illness
what are the positives of a CT scan?
- Non invasive
- Shows bone, blood vessels and soft tissue
what are the negatives of a CT scan?
- Images only show brain structures
- Images are of inferior quality to those from MRI
