Neurological and Psychiatric
Disorders summary
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,Brain Imaging 3
Depression: Clinical Aspects 7
Depression: Preclinical Aspects 9
ADHD: Clinical and Preclinical Aspects 14
Preclinical Models of Compulsive Drug Use 17
Dementia: Clinical Aspects 20
Dementia: Preclinical Aspects 23
Autism Spectrum Disorder(s) 25
Obsessive Compulsive Disorder (OCD) 27
Multiple Sclerosis: Clinical Aspects 31
Multiple Sclerosis: Pathogenesis 34
Brain Injury Rehabilitation and Holistic Neuropsychological Rehabilitation 37
Stroke and Rehabilitation 41
Parkinson’s Disease: Preclinical Aspects 46
Parkinson’s Disease: Rehabilitation 49
Parkinson’s Disease: Clinical Aspects 53
Brain Tumors 56
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, Brain Imaging
NEUROIMAGING
- Why use it?
- Clinic
- Diagnosis/prognosis of neurological disorders
- CT, MRI, MRA, MRS, PET, X-ray
- Research
- Improve diagnostics of neurological disorders
- Prediction of disorders
- Understand biological processes (using advanced imaging techniques)
- Anatomical planes:
- Axial (transverse): separates upper and lower halves of the body
- Coronal: separates front and back of the body
- Sagittal: separates left and right sides of the body
STRUCTURAL BRAIN IMAGING
- Reasons for brain imaging:
- Identifying the e ects of a stroke
- Locating cysts and tumors
- Finding swelling and bleeding
- Disease-related lesions
- Common structural brain/skull imaging:
- X-ray: shows bone/skull only, not the brain
- Best used to detect bone fractures
- CT: shows brain, but not in great detail
- Shows presence of any larger bleed, stroke, lesions, or masses
- Quick test, so preferred during emergency
- Visually: worse resolution (more pixels), bones light up (skull appears white)
- MRI: shows brain in greater detail
- Shows presence of smaller bleeds, stroke, lesions, or masses
- Long test, so preferred with long-term symptoms
- Visually: better resolution, skull appears dark (due to little water contents of tissue), fat
on skull appears white
- Air and bone give no signals on an MRI scan, and therefore appear dark
- Magnetic Resonance Imaging (MRI):
- Strong magnetic eld, so magnetic materials have to be kept out of the room
- Magnetic eld is measured in Teslas
- Advantages of MRI:
- Non-invasive
- Non-ionizing radiation
- High soft-tissue resolution and discrimination between tissue types
- Morphological information as well as functional information
- Disadvantages of MRI:
- Time consuming
- Contraindications for MRI: patients that cannot be scanned due to e.g. presence of
pacemaker or surgical plates
- Loud noise
- Sequence needs to be adapted to question
- Sequence: di erent types of MRIs
- Technique behind MRI:
- MRI uses magnetism and radio frequency signals to acquire images
- MR images are based on density of protons
- 1) No magnet: hydrogen atoms (protons) in body are randomly positioned
- 2) Magnet on: most protons get aligned in the direction of the magnetic eld
- 3) Radio pulse: protons spin and move orthogonally
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, - 4) Protons relax: release radio signal
- The time that it takes for the protons to return to their original position is
measured, resulting in di erent signals for di erent types of tissues
- Main ‘techniques’ in MRI:
- T1 weighted images:
- Contrasts fat/water
- Used to look at the anatomy/enhancement of the brain (e.g. atrophy, lesions)
- Visually: grey matter appears grey, white matter appears white
- T2 weighted images:
- Contrasts water/tissue
- Used to look at the pathology of the brain (e.g. edema)
- Visually: cerebrospinal uid appears white, grey matter appears light grey
- Tip: in T2 (tWo), Water (i.e. CSF) = White
- T1 vs. T2: what you want to see determines what sequence you will use
- T1 detects tumors more easily, whereas T2 detects edema more clearly
- Fluid-attenuated inversion recovery (FLAIR):
- T2 weighted MRI scan
- “Inversion Recovery”: CSF (i.e. white signal) is suppressed, thereby improving
contrast
- Easier to distinct the (entire) damaged area
- T1 vs. FLAIR:
- T1: neuroanatomical changes, therefore hard to see edema on T1 image
- FLAIR: changes related to water, therefore very obvious to see edema on T2
or FLAIR
- Double Inversion Recovery (DIR):
- T2 + FLAIR
- Suppress both CSF and white matter signal (i.e. fat tissue)
- Used to detect lesions/plaques in white matter, or between grey/white matter
- Magnetic Resonance Angiography (MRA):
- Can be used to detect arteriovenous malformation (AVM) and ischemic stroke
- AVM: abnormal connection between arteries and veins; usually asymptomatic
- Brain imaging in research:
- Qualitative
- Standard clinical practice
- Look for pathology
- Quantitative
- ‘Numbers’ as output
- Understand biological mechanisms
- Compare patient groups to healthy controls
- Di usion Tensor Imaging (DTI):
- MRI of how white matter tracts are connected (i.e. how the brain is ‘wired’)
- Tractography can show an overview of white matter connections
- Why does white matter matter?
- Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, schizophrenia, etc.
- DTI is used to assess white matter integrity
- Healthy nerve: passage of nerve impulse
- Damaged nerve in MS (with areas of demyelation): interference in passage of nerve
impulse
- Technique behind DTI: the di usion of water molecules through axons is measured
- Isotropic: di usion is the same in every direction
- Anisotropic: di usion varies with direction
- 4 main di usion outcome parameters for microstructural integrity:
- Fractional anisotropy (FA): directionality of the water di usion
- Mean di usivity (MD): the average di usivity
- Axonal di usivity (AD): di usivity along the axon
- Radial di usivity (RD): di usivity perpendicular to the axon
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