Neuroscience techniques Flashcards
What is resolution
the extent to which a method can sample the brain’s function
What is spatial resolution
Precision in the localization of brain activity/function
What is temporal resolution
Precision in the timing of brain activity/function
What do structural MRIs do
Produces detailed images of the brain to investigate the structure
What do sMRIs rely on?
The magnetic properties of hydrogen nuclei
What do structural MRIs measure
Size of cortical matter, size of specific parts of the brain, differences in brain structure between people
What are advantages of structural MRIs
Non invasive, little health risk, high spatial resolution
What are disadvantages of structural MRIs
cramped area, expensive, only information on the structure alone
What does a functional MRI measure
Changes in the concentration of oxygen in the blood relating to neural activity
What is the BOLD signal
Blood oxygen level dependent
What is the haemodynamic response
When the BOLD signal evolves over time as a response to increase in neural activity
What are the 3 phases in the haemodynamic response
Initial dip, overcompensation, undershoot
What happens in the initial dip of the haemodynamic response
neuronal consuming of oxygen, small rise of deoxyhaemoglobin so a reduction of the BOLD signal
What happens in the overcompensation phase of the haemodynamic response
increased consuming of oxygen, more blood flow, BOLD signal increases due to increase of blood flow
What happens in the undershoot of the haemodynamic response
blood flow + oxygen consumption dip and return to original levels, relaxation of venous system, temp increase of deoxyhaemo
When are functional MRIs used?
Investigating which brain areas are active under certain conditions, the differences of brain activity between people, changes in brain activity pre and post interventions
What did Milne et al find?
Memory issues are reported in patients with MDD and reflects the hippocampal changes. Increased activity in the right hippocampal area when comparing the control and people with MDD
What are the advantages of functional MRIs
non invastive, good spatial resolution, low health risk
What are disadvantages of functional MRIs
noisy, cramped space,
very expensive machine,
poor temporal resolution,
indirect measure of brain activity
What do EEGs do
Investigate the electrical activity of the brain
How do EEGs work
Neurons produce electrical charges that form patterns called brain waves. The electrodes detect brain wave. The EEG machine amplifies the signals and records them in a wave pattern
When are EEGs used
Investigate brain activation with milliseconds resolution, investigate changes in brain activity between groups, biomarkers of disorders. Patterns of brain waves (alpha, beta, gamma, theta) each associated with specific cognitive functions/behaviours. For ERPS
Where do EEGs signals originate
In the post synaptic dendritic
What are the currents for EEGs signals
Passive and active currents
What are advantages of EEGs
Non-invasive
Inexpensive and flexible
Good temporal resolution (ms range)
Direct measure of brain activity
What are disadvantages of EEGS
Poor spatial resolution
Mostly restricted to activity from cortical areas
What do ERPs measure
The amount of electrical activity due to a stimulus
What gives the peaks in an ERP wave
Dipoles which summate to the skull
What are dipoles
Separation of electrical charges that create an EM field from different neurones and regions
What do TMS do
Activate or modulate neuronal activity in the brain
which allows infering of brain behaviour relations
What happens when there is a change in the electric current in TMS
A magnetic field is created which will incrase the rate of change in the electric current which induces a secondary electric current into the nearby wire
Where is the secondary current induced
In neurons below the stimulation site
When are TMS used
To investigate the relationship between brain areas and behaviour. Stimulating the areas of the brain with decreased activity
What are advantages of TMS
Non-invasive
Quick
Relatively cheap
What are disadvantages of TMS
Some side effects (e.g. headaches, scalp pain, dizziness)
Still not sure how long the effects last
Poor spatial and temporal resolution
What do animal models do
They target lesion of defined brain areas with targeted training and analysing the brain structures
How is animal models invasive
There is invasive recording of neural activity and brain stimulation
What does animal models allow
Causal conclusions
