Olivia MRI Lectures

What are neurons

The core units of the nervous system.

What do dendrites do

Receive signals.

What does the cell body (soma) contain

The nucleus (DNA) and mitochondria (energy).

What is the function of the axon

Sends electrical signals to terminals.

What is myelin

A fatty layer that increases signal speed.

What is grey matter composed of

Neuron cell bodies and local connections.

What is white matter composed of

Axons connecting different brain regions.

What is the function of cerebrospinal fluid (CSF)

Cushions and protects the brain.

What are the functions of grey matter

Sensation, perception, motor control, and cognitive functions like memory and decision-making.

What are risk factors for grey matter damage

Ageing, hypertension, diabetes, smoking.

Which conditions are associated with grey matter damage

Alzheimer’s, Parkinson’s, stroke, trauma.

What does MRI stand for

Magnetic Resonance Imaging.

What does MRI measure

Signals from hydrogen protons in water/fat.

What are voxels in MRI

3D pixels each containing thousands of neurons.

What is the resolution of structural MRI

How long does a structural MRI scan take

~5 minutes for a high-resolution image.

What is structural MRI used for clinically

Identifying tumours, stroke, and traumatic brain injury.

What does structural MRI measure in research

GM, WM, CSF volume, cortical thickness, and subcortical structure shapes.

What are limitations of structural MRI

Indirect data, noisy, resolution limited to millimetres, artefacts affect quality.

What is the focus of diffusion imaging

White matter.

What is white matter composed of

Long axons often myelinated.

What are risk factors for white matter issues

Ageing, hypertension, diabetes.

What conditions are associated with white matter damage

MS, stroke, Parkinson’s, autism.

What principle is diffusion MRI based on

How water molecules diffuse.

What does diffusion MRI reveal

Direction of WM tracts and axonal integrity.

What is the resolution of diffusion MRI

1–3 mm.

Why does diffusion MRI require many images

To map fibre directions accurately.

What challenges does diffusion MRI face

Crossing fibres and artefacts.

What is diffusion MRI used for clinically

Detecting tumours, demyelination, stroke damage, neurodegeneration.

What is diffusion MRI used for in research

Mapping WM tracts, measuring WM integrity, correlating with traits.

How does WM integrity relate to anxiety

Decreased integrity, e.g., lower amygdala-prefrontal connectivity in GAD.

List an example diffusion MRI analysis step.

Acquire diffusion MRI images.

Why is diffusion MRI limited

Indirect measure, can't detect individual fibres or axon size, motion artefacts.

Where is functional activity processed

In grey matter.

What does fMRI measure

Blood oxygen changes (BOLD response).

What is the spatial resolution of fMRI

1–3 mm.

What is the temporal resolution of fMRI

1–3 seconds per image.

What does the hemodynamic response reflect

Changes in blood flow due to active neurons needing oxygen and glucose.

What is fMRI used for clinically

Pre-surgical mapping (e.g., language areas).

What is fMRI used for in research

Mapping brain activity, studying connectivity, comparing groups.

Describe the milkshake vs tasteless drink task.

Tracks BOLD response in gustatory cortex using regression model.

What are steps in an fMRI experiment

Design task, collect data, model HRF, analyse and interpret.

What are fMRI limitations

Indirect measure, only detects relative changes in oxygenation, movement sensitive.

What are complementary techniques to fMRI

PET and EEG.