Functional Neuroimaging Flashcards
Imaging of functional activity can be done ______ or ______.
direct or indirectly
What does the indirect imaging measurements quantify?
cerebral blood flow, blood oxygen levels, or oxygen or glucose consumption
Is electric and magnetic signals direct or indirect?
direct measurement of neural activity
Electroencephalography (EEG)
electrical potential produced by large populations of neurons are measured by electrodes placed on the scalp
EEG provides continuous recording of what?
recordings of overall brain activity
What are the recorded measured signals of an EEG referred to as?
Electroencephalogram
Predictable EEG patterns are associated with different behavioral states; Why would you compare EEG readings to neurotypical patterns?
in order to detect abnormalities
What is the quality of EEGs?
Good temporal quality, poor spatial quality
- Signal can be distorted as it passes through the tissue
Magnetoencephalography (MEG) measures….
neural activity by capturing the magnetic fields produced by active neurons
What is the quality of MEGs?
similar temporal quality as EEG, but better spatial resolution due to lack of signal distortion
How are MEGs applied?
during neurosurgery
Why are MEGs useful?
for identifying cortical functionality
Is measuring metabolic signals direct or indirect?
indirect measurement of neural activity
Positron Emission Tomography (PET) measures….
local changes in cerebral blood flow
Areas of increased blood flow on a PET scan = what?
increased neural activity
What is required for PET scans?
Radioactive tracer injected into the bloodstream (tracer emits photons/gamma rays)
How does a PET scanner detect blood flow?
detects the location of emitted gamma rays
When are PET scans employed?
- 1st during a control condition (subject at rest)
- 2nd during experimental condition (subject engaged in a cognitive task)
What will brain areas of heightened neural activity emit?
will emit the highest levels of gamma rays due to increased blood flow in those regions
What are results of PET scans reported as?
as a change in regional cerebral blood flow (rBCF) between two conditions
What are the downsides of PET studies?
requires injection of radioactive isoptope
- Invasive procedure
- Limited number of tests due to exposure
Functional Magnetic Resonance Imaging (fMRI) relies on what?
relies on the magnetic properties of hemoglobin
fMRI measures
the ratio of oxygenated to deoxygenated hemoglobin in the bloodstream
What is the ratio of oxy vs. deoxy hemoglobin referred to as?
blood oxygenation level-dependent (BOLD) effect
As a brain region becomes more active (during fMRI) what happens to the BOLD effect ratio?
Cerebral blood flow to those areas increases thus the ratio of oxygenated to deoxygenated hemoglobin in that region increases
Why is fMRI a preferred neuroimaging technique?
- Non-invasive and can be repeated
- Found in most hospitals and require less staff to run
- Spatial resolution is better than PET
- Improve temporal resolution is possible with fMRI due to the rapid measurement of the BOLD signal
Previous view of evolving brain theory?
- Neural circuitry is static
- Cognitive function and memory are localize
- Information processing involves only serial processing
- Brain function(s) vulnerable to single site injury
- Clinical supporting evidence limited
Current view of evolving brain theory?
- Neural circuitry is plastic
- Cognitive functions and memory are distributed
- Information processing involves serial, parallel, and reciprocal
- Brain activity is driven by internal, intrinsic cycles of network activity (intrinsic and extrinsic interaction)
- Brain function(s) resistant to degradation by single site injury
- Clinical supporting evidence strong
Cognitive network neuroscience is a branch of neuroscience that studies what?
how brain dynamics within the human brain networks support cognitive function
What are single-source divergent networks?
functional neural pathways comprised of neurons within specific nuclei found that release one type of signaling molecule that influence numerous other target brain areas
Cognitive network characteristics
- Appear early during embryonic development
- Support all cognitive functions of the brain
- Constantly modulate neural activity and are referred to as “brain state modulatory controls”
- Organized in a hierarchy (local division of labor within the network)
- Exhibit functional stability in the face of local network damage
- Are created and altered by synaptic plasticity processes
- Consist of many long-reaching axonal branches
- Categorized by the neurotransmitter utilized
