Cognitive Neuroscience: Methods Flashcards
How does an MRI work
-employs a powerful magnet which produces a strong magnetic field
-forces protons which exists in every cell in our body to align with that magnetic field
-machine emits a radio frequency pulse which pushes makes the protons out of their usual position
What are we measuring with MRI
Detects different tissue types depending on how quickly protons release energy and return to their normal position when the radio frequency pulse is turned off
What does BOLD stand for
Blood oxygenation level dependent
-supply of oxygen in the blood vessels surrounding that part of the brain
What is the haemodynaic response
Use up oxygen for the body to create an equilibrium
What are the different magnetic properties between oxygenated to deoxygenated blood
Oxygenated blood increases MRI signal
Deoxygenated blood decreases MRI signal
How many seconds is the MRI response delayed
6 seconds after the stimulus
How is an MRI non-invasive
Safe, no tissue damage
How does a PET scan work
-Inject people with tracers (specially designed radioactive ligands)
-travels to a tissue/organ/area of the body and binds there
What is an EEG measuring
Activity measured comes from the activity of thousand of neurons beneath each electrode
Voltage fluctuations show on an EEG reading
What is event related potentials (ERPs)
-small voltage generated in the brain in response to specific events
-summed activity of postsynaptic potentials when a large number of neurons fire in synchrony
What is TMS
Transcranial magnetic stimulation
-stimulate or decrease activity in certain regions of the brain
What is TMS
-Magnetic pulses over the scalp, delivered quickly
-induces small electric currents- alter the firing patterns of neurons
-interfere with cognitive processes such as perception and motor control
How does TMS work
-electrical burst is short-lasting, rises to maximum and reverse back towards 0
-stimulate superficial areas of the cortex, not deeper brain structures
What is the coil
Detects brain activity
Maximum electric field induced is in the ring-shaped area underneath the coil
What is the single coil in TMS
Used in early studies, less focal, activates larger regions of the brain
What is the figure of eight coils in TMS
Intensify the electrical field at the point of overlap- good to target specific regions
More focal
What is the double cone in TMS
Good for bilateral or wide-area stimulation as covers both sides of the head
What is the H coil in TMS
Less focal but covers large networks and deeper brain regions
How do we know what intensity to use in TMS
Calibrating motor evoked potential (MEP)
-the intensity threshold is determined for each participant separately
-increasing intensity until finger twitches- knows area of brain is disrupted by electrical bursts
How do we know what frequency to use with TMS
Depending on the outcome, a single short pulse can be delivered, or repetitive pulses rTMS
If the frequency of TMS is under 1 hertz what is the outcome
Decreases activity in an area of the brain
If the frequency of TMS is over 1 hertz what is the outcome
Increases activity in an area
