Neuroimaging Flashcards
What are the advantages and disadvantage of EEG ?
Advantages:
- good time resolution
- portability
- affordable
- silent (can be done during auditory processing)
- can be combined with other methods
Disadvantages ?
- low spatial resolution
- artifacts
What are the advantages and disadvantages of MEG ?
Advantages:
- good time resolution
- reduced preparation time
- signal unaffected by skull and scalp
Disadvantages:
- expensive
- low spatial resolution
- subject cannot move
- not portable
- sensitive only to neurons in sulci
What can cause artifacts on EEG ?
- Eye lid movement
- scalp muscle activity
- pacemakers
- movement (= change in impedance)
- electrode-wire contact
- poor grounding
- sweating
What are brain oscillations ?
Rhythmic fluctuations of repeated electrical activity generated by the activity of neurons.
Can be spontaneous or in reaction to a stimulus.
What is neurofeedback training ?
Expected or desired aspects of cortical and subcortical activation can be achieved or modified through sensory (visual and auditory) stimulation, controlled by a biofeedback system that rely on EEG information.
What are the types of neurofeedbacks ?
- univariate : blood oxygen level dependent
- decoded : multi voxel activity pattern
- connectivity : functional connectivity between regions
For which conditions has NFT been proven efficient ?
- ADHD
- ADH
- epilepsy
- neurocognitive disorders
- ABI in connection with facilitation, sensory augmentation and functional training
What are the advantages of MRI compared to CT ?
- no use of ionizing radiation
- contrasts have less side effects
- comparable resolution but not the same tissues
- more detailed even without contrast
What are the disadvantages of MRI compared to CT ?
- Claustrophobic patients
- limitation to weight and size of patient
- very noisy
- long time of procedure (not suitable for emergencies)
- sequential (no generalization possible)
What are the characteristics of T1 weighted image ?
White matter appears brighter than grey matter:
Hypointense signal:
- cerebro spinal fluid
- edema
- tumor
- infection
- inflammation
- hemorrhage
- calcification
Hyper intense signal:
- chronic hemorrhage
- fat
- protein rich fluid
- slow flowing blood
- contrast
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- melanin
- blood
- fat and slow blood flow
- proteins and paramagnetic substances
- cholesterol and contrast
What are the characteristics of T1 weighted image ?
White matter appears brighter than grey matter:
Hypointense signal:
- cerebro spinal fluid
- edema
- tumor
- infection
- inflammation
- hemorrhage
- calcification
Hyper intense signal:
- chronic hemorrhage
- fat
- protein rich fluid
- slow flowing blood
- contrast
What will cause unbalanced delta waves ?
Slowest in the human brain
Too much:
Dépression
Too little:
Sleep disorders and dissociation
What will cause unbalanced Theta waves ?
Too much:
Lack of focus
Too little:
Memory disorders
What will cause unbalanced alpha waves ?
Strongest EEG brain signal
Too much:
Anxiety
Too little:
Exhaustion
What will cause unbalanced beta waves ?
Too much:
Obsession
Too little:
Dépression and anhedonia
What will cause unbalanced SMR waves ?
Sensorimotor rhythm
Too much:
Dépression
Too little:
Attention disorders
What will cause unbalanced gamma waves ?
Fastest brain wave
Too much:
Paranoïa
Too little:
Reasoning and perceptual deficits
What are the characteristics of T2 weighted images ?
Grey matter appears brighter than white matter.
Hypointense signal will reveal: CSF, edema, infection, inflammation, subdurral or subacute haemorrhage and calcification.
Hyperintence signal will reveal: calcification, fibrous tissue, iron and melanin.
What is FLAIR used for ?
Fluid Attenuated Inversion Recovery.
Efficient in the evaluation of vascular injuries, SDH and multiple sclerosis.
What are the purposes of T1WI ?
- Intracerebral bleeding
- structures with high fat concentration
- small anatomical details
What are the purposes of T2WI ?
- Edema
- Demyelination
- Infarction
- Chronic haemorrhage
What are the purposes of FLAIR ?
- Edema
- Demyelination (most specific)
- Periventricular and pericortical hemorrhage
What are commissural fibers ?
Connection between hemispheres.
- Corpus callosum
- Anterior commissure
- Fornix
What are the projection fibers ?
Connection from/to the cortex:
- optic and acoustic fibers
- thalamocortical fibers
- internal capsule
- cortico pontine
- corticospinal tract
What are the association fibers ?
Connexions within hemispheres:
- short U fibers (between adjacent gyri of the brain)
- inferior longitudinal fasciculus
- inferior fronto occipital fasciculus
- middle longitudinal fasciculus
- uncinate (from prefrontal to temporal cortex)
- Cingulum
What is the role of the superior longitudinal fasciculus I ?
Connects prefrontal regions with parietal regions and is involved in higher cognitive functions, planning and analysis and spatial awareness.
What is the role of superior longitudinal fasciculus II ?
Connects prefrontal regions with parietal and occipital regions. Integration between processed visual information and cognitive functions related to decision making and prospection.
What are the functions of superior longitudinal fasciculus III ?
Connecting prefrontal regions with contralateral occipital regions. Involved in visual attention and tracking.
