Which are structural techniques?
X-ray and CT
MRI
Contrast agents
Diffusion Tensor Imaging
PET
fMRI
EEG
MEG
ECoG
Which are functional techniques?
CT
X-ray and CT techniques are great at showing:
Blood vessels
Different brain regions
Ventricles
Electrical activity
_________ ventricles could be due to tumour; _________ ventricles could be due to schizophrenia
Shrunken; expanded
Expanded; shrunken
Which technique measures proton densities?
Electrocorticography
What is the most common contrast agent?
Gadolinium
TM tomato
Haemoglobin
Phosphorescents
What is true of Diffusion Tensor Imaging?
Shows fibre tracts
Measures hydrogen densities
Is a structural MRI technique
Water molecules diffuse more easily through the cross-section of neurons than along the long axis
Makes a lot of assumptions
Which technique involves the injection of a radioactive isotope?
What are examples of radioactive isotopes?
Oxygen
Glucose
Tm tomato
The brain takes about % of the body's weight, but uses about % of its nutrients
What is true of Regional Cerebral Blood Flow (rCBF)?
Active regions release Nitrous Oxide to local arterioles
Nitrous Oxide released retroactively
Causes arterioles to constrict
Very slow change
Causes change in ratio of de:oxygenated blood
Which techniques are based on the close association between vasculature and metabolism?
Which techniques measure electromagnetic fields generated by ionic current flow in active neurons?
Which techniques are invasive?
Which technique involves placing grids of electrodes directly on the surface of the brain?
Single-unit recording
Diffusion tensor imaging
Contrast X-ray angiography
When is Electrocorticography used?
Localise epileptic foci
Opportunistic research
Avoid eloquent areas during surgery
Research into language
Patients with mild clinical problems
What does MEG measure?
Strength of magnetic field
Strength of electrical field
Location of magnetic field
Location of electrical field
What is contained in a "dewer" and used to keep the SQUID close to absolute zero?
Liquid helium
Nitrous oxide
Dry ice
Hydrogen
Why do MRI scans have to be done after MEG?
Because MRI scans magnetize tissues for weeks
Due to risk of overheating the machine
Which technique induces electrical current flow by producing strong magnetic fields?
TMS
TES
TDS
tDCS
Which technique delivers a small electrical current?
tCDS
Which is true of children's Fusiform gyrus response to faces, compared to adults:
Equally strong but later
Weaker and later
Stronger and earlier
Children's fusiform gyrus does not respond to face stimuli
What is true of standard template brains?
Normalise brains
Allows statistical analyses on brain maps
Is a standard size and shape
Used for structural brain images
Which standard template brain is based on a single well-characterised brain?
Talairach atlas
MNI atlas
Tesseract atlas
Monoamine atlas
Which standard template brain is based on an average of hundreds of MRI scans?
When is fMRI mostly used?
Clinically
Research
Pre-surgical and radiotherapy planning
Identify eloquent cortices
When is MEG usually used?
Rarely in hospitals
Localising epileptic foci
Pre-surgery mapping of eloquent cortices
What is true of hippocampal theta oscillations?
Very active in novel environments
Ties together place cells
Tuned to specific locations in an environment
Different place cells fire at different phases of the theta oscillation
Important for semantic memory
Measured by EEG
Which regions make up the Default Mode Network?
Cingulate
Parietal
Frontal
Temporal
Occipital
Limbic
Diencephalonic
Which techniques are based on machine-learning?
Connectivity
Decoding
Connectomics
Machine reading
What is true of Connectivity analysis?
Based on graph theory
Emphasises brain structures over brain networks
Multi-voxel pattern analysis
Based on machine-learning
What is true of Decoding techniques?
Analyses patterns of activity to complex stimuli
Analyses patterns of activity to simple stimuli
Why is the reproducibility crisis particularly acute in neuroimaging?
Huge amount of data
Increased possibilty of false positives
Too expensive to have large samples
Large researcher degrees of freedom
Statistical double-dipping
Results tend to have a large impact on society
Pre-registration of hypotheses
Data sharing
How has fMRI improved?
Gone from 1.5 T to 7 T
Better image stability
Better signal:noise ratio
Strongest magnets can reslve activity in different cortical layers
Higher temporal resolution
How has MEG improved?
Moving from SQUID to Optically Pumped Magnetometers
Human Neocortical Neurosolver
Dramatically improved data acquisition capabilities
Strongest magnets can resolve activity in different cortical layers
What are Optically Pumped Magnetometers?
Require liquid helium
Sensors placed directly on scalp
But reduced signal:noise ratio
Uses computers to map underlying circuit-level activity
Only one place in the world has them
Why isn't neuroimaging useful for psychiatric diagnosis?
Low specificity
High sensitivity
High standardization
Most psychiatric imaging studies are done on groups
Different disorders have similar neural patterns
DSM has much higher validity
Who said that we are currently not able to use brain imaging for psychiatric diagnoses, and may not ever be?
Farah & Gillihan
Aubertin & Bouillaud
Flouren & Gerschwind
Aside from diagnosis, why might brain imaging be useful in psychiatry?
Can suggest new treatments
DBS came from identifying deep brain areas that are hypoactive in depression
Quantifying and predicting treatment response
Classifying syndromes based on neuroimaging profile
Real-time neurofeedback may be a treatment in itself
