Lecture 9 - Brainimaging Technologies Flashcards
What are the three aspects of brain and mind theory?
Mentalism, Dualism, and Materialism
What is Mentalism?
Behaviour is solely governed by the mind while the brain is irrelevant
What is Dualism?
Both mind and brain control behaviour
What is materialism?
Brian supports and governs mind and behaviour. All the mental states and behaviours are materialistically explainable
What do neuroimaging/ Brainimaging technologies do?
They look into the brain by turning neural systems into an image
What are the things neuroimaging/ brainimaging technologies look at? (6 things)
- Morphology/ Structure
- Anatomical network structure
- Functional network structure
- Functional association
- Dynamic activities (change with time)
- Event-related brain response
What is morphology/ structure?
The gross pattern that can be seen with our bare eyes (e.g. identifying shrieked brain due to Alzheimer’s disease)
What is anatomical network structure?
The pattern of neural tract connecting different places in the brain, which is reviewed by DTI
What is functional network structure?
An abstract and non-physical kind of connection that can only be inferred and that explains the function
What is Functional Association?
want to know the brain is associated with which function
What is dynamic activities (change with time)?
To extract information from the dynamic patterns in brain as brain is not static and constantly changes
What is Event-related brain response?
To study brain responses to a certain stimuli/ certain activity
How can you test the event-repeated brain response?
Present some stimuli to put information to the participants’ brain and then measure the ongoing activity and evoke response activity (a specific brain response to a specific stimulus to study the characteristics of brain responses to a certain stimuli)
Why we need neuroimaging?
It has been confirmed that the brain is related to some certain variables and is measurable
What variables are found to be related to brain activity? (7 variables)
- Cognitive ability
- Mental states (the overall state of cognitive system)
- Functional processes
- Emotional activity
- Subjective feelings
- Pathological states (malfunctioning in some parts)
- Development/ aging-related variations
What is invasive in brainimaging technologies?
A little harmful because it puts things inside your body
What is non-invasive in brainimaging technologies?
There is nothing penetrating your body (no technologies put in the body)
What is the measurement of MRI?
Hydrogen behaviour
Is MRI invasive/ non-invasive?
Non-invasive
What is MRI
MRI uses a magnetic field, radio frequency pulses and a computer to produce detailed 2D images pictures of organs, soft tissues, bones and virtually all other internal body structure.
What does the measurement in MRI in terms of timing?
Measures the returning timeof different tissues in different environment.
What is the mechanism of MRI (i.e. being composed of what)?
organ (brain) -> tissue -> cell -> molecule -> atom -> proton
What direction is the proton?
Every proton has a spinning direction and it is not static.
What does MRI target on?
Behaviour of protons
How does MRI measure the returning time?
MRI applies magnetic field to align with the direction of protons. Then radio frequency is applied to turn the direction of protons. Then, the removal of radio frequency will return to the orignal state to align with magnetic field. The returning time for different tissues are different.
What does different colour for MRI infer?
- light pixel indicates a shorter returning time (e.g. in water)
- dark pixel indicates a longer returning time (e.g. in blood)
What is the measurement of fMRI?
Changes in blood oxygen level (assumed to reflect neuronal activity) [try to measure the the temporal variation of blood dynamics]
What does fMRI produce?
Produce a 3D image of activation maps showing which parts of the brain are involved in a particular mental process
The signal of MRI is being measured by MRI as a function of what?
A function of time that can infer the functions
Is fMRI invasive/ non-invasive?
Non-invasive
What does DTI rely on?
Magnetic Resonance Imaging (MRI) signal detection
What is the measurement of DTI?
Water flow direction (about the diffusion of water)
Is DTI invasive/ non-invasive?
Non-invasive
What information does DTI offer?
Offers information about the water molecule motion (along the neural fibres [direction of axon])
What is DTI being used for
Fibre tracking
What is the measurement of CT?
X-ray absorption
Is CT invasive/ non-invasive?
Non-invasive (radioactive)
What does CT use?
Uses a combination of X-rays and computer technology
What does CT produce?
Produce horizontal, or axial, images (slices) of the body
What is the risk of CT?
Large amount of X-ray radiation is harmful
Is fNIRS of blood oxygen signal invasive/ non-invasive?
Non-invasive
What is the measurement of fNIRS of blood oxygen level?
Blood oxygen level
What is the advantage of using fNIRS of blood oxygen level?
Less expensive and highly portable
What is the mechanism of fNIRS of blood oxygen level?
Hemoglobin and deoxygenated-hemoglobin absorb the near-infrared light differently, therefore the detector will sense the change of blood oxygen level
How is the level of absorption of the near-infrared light depending on what?
Depending on the level of oxygen, the level of absorption of of the near-infrared light (lasers) is different
What is applied for fNIRS of blood oxygen level?
Apply infrared “lasers” to travel though the brain and the change of blood oxygen l’élève is detected by detector
Is PET invasive/ non-invasive?
Invasive
What is the measurement of PET?
Tissue metabolic activity
Is PET invasive/ non-invasive?
Invasive
What reflects the measurement of tissue metabolic activity in PET?
Radiation of injected radionuclide
What is indicated for the measurement of radiation?
Glucose intake
What is injected in the body in PET?
Fludeoxyglucose (radiative glucose)
What are the three brainimaging technologies responsible for neuronal signal management?
MEG, EEG, and ECoG
What is the mechanism of neuronal signal measurement?
Parallelly oriented neurons generate current activity, causing potential differences on the scale (EEG) and cortex (ECoG). The current further induces magnetic field (MEG).
What is the measurement of MEG?
Neuromagnetic signals (to capture magnetic field)
Is MEG invasive/ non-invasive?
Non-invasive
What does MEG detect?
detects magnetic field generated by our brian
What is the measurement of EEG?
Neuroelectrical signals
Is EEG invasive or non-invasive?
Noninvasive
What does EEG produce?
Produces image of the electrical signals on scalp level of the brain
What is attached to the brain in EEG?
Attaching electrons to the brain
What is the measurement of ECoG?
Neuroelectrical signals
Is ECoG invasive or non-invasive?
Invasive
What does ECoG produce?
Produces image of electrical signals from the cortex that is being measured indirectly
What does temporal and spatial recognition determine the neuroimaging technologies?
The performance of different neuroimaging technologies
What is the process of processing?
We receive stimulus, and the brain will go through sensation of singals, then perception, afterwards evaluation (central processing), then response selection (to make response), and then output your behavioural action. The entire processing takes < 1 second.
What is temporal resolution
you need neuroimaging technology with high temporal resolution to capture the variation from different sub stages of processing for you to infer what happens in each stage due to the short duration of processing
What is a bad temporal resolution?
Unable to help you measure at what time each stage happens
How is the collection of data data being done?
In a discrete way (non-continuous way)
What does sampling rate infer?
- High sampling rate -> higher resolution
- Low sampling rate -> lower resolution
What is a technology with high temporal resolution?
The technology can quantify and associate signals with different cognitive stages that helps you define activities in different stages
What is spatial recognition?
The quality that the technology an precisely tell you from which position of brain generates the activity/ task
Temporal resolution and Spatial resolution of MRI
No Temporal resolution and High Spatial resolution
Temporal resolution and Spatial resolution of fMRI
Low Temporal resolution and High Spatial resolution
Temporal resolution and Spatial resolution of EEG
High Temporal resolution and Low Spatial resolution
Temporal resolution and Spatial resolution of ECoG
High Temporal resolution and High Spatial resolution
Temporal resolution and Spatial resolution of MEG
High Temporal resolution and Low Spatial resolution
Temporal resolution and Spatial resolution of DTI
No Temporal resolution and High Spatial resolution
Temporal resolution and Spatial resolution of X-ray CT
Very Low Temporal resolution and Medium Spatial resolution
Temporal resolution and Spatial resolution of fNIRS
Low Temporal resolution and Low Spatial resolution
Temporal resolution and Spatial resolution of PET
Very Low Temporal resolution and Low Spatial resolution
What measurement has a high temporal resolution?
Measuring neural activity
What are the basic procedures in conducting a brainimaging research?
- Identify a research question
- Choose a suitable brainimaging technology
- Design an experiment
- Analyse the data
- Making Conclusion