Toolkit 1 - Neuroimaging Flashcards
What is Magnetic Resonance Imaging (MRI)?
Invented in the 1980s
Can scan and create images of brain structure
Beneficial to detect brain abnormalities (e.g. tumors)
Can test structural differences in brain of different groups of people
How do we take images of a 3D organ?
In slices
Coronal plane, Horizontal plane and sagittal plane
Slices are then used to reconstruct a 3D model
What is a functional mri?
The brain during cognitive tasks
How do we get from static images to brain function?
We are taking a lot of images in rapid succession while people are doing things
What is the use of fMRI?
Enables us to look at brain function
Utilizes what we know about cell metabolism to make inferences about neuronal function
What is BOLD?
Blood oxygen level dependent
Neurons need oxygen.
Oxygen is transported by hemoglobin from the lungs to the brain cells via blood flow.
The MRI signal is sensitive to deoxyhemoglobin.
During brain activity the level of deoxyhemoglobin in the blood changes.
What is PET?
Positron Emission Tomography
Very similar to fMRI, same machine, but uses a contrast agent
- radioactive tracer substance injection to make blood flow more visible due to positron emission
- no worries, very safe
- more direct measure of blood flow rather than magnetic field differences based on deoxygenation differences
What is the best imaging techniques?
Speed (PET is much slower than fMRI; tradeoff between temporal and spatial resolution).
Sensitivity (PET is more sensitive than fMRI). Signal changes are small, not equal representation of different parts of the brain.
Accuracy (fMRI is more accurate than PET). Better to detect locations, especially if small brain area.
Describe the results of an fMRI
Colors indicate locations of increases and decreases in brain activity.
Activity recorded in voxels (3-D pixels)
Use subtraction method after data processing
What are neural networks?
Interconnected areas of the brain that communicate with each other
What is DTI and whats it used for?
Diffusion Tensor Imaging (DTI) can make nerve fibre tracts (physical connections between neuron tracts) visible
Through DTI across multiple individuals, we can also build realistic models of neural structures
e.g. the perisylvian pathway connecting Broca’s area and Wernicke’s area as well as the anterior temporal pole
What is functional connectivity?
Neurons do not need to be physically connected to work together and form neural networks.
When neurons show systematic covariance/synchronisation during certain tasks, we speak of functional connectivity
What is the central principle of cognition?
Most of our experience is multidimensional.
