all 1-2 weeks Flashcards
Structural and functional. Structural used for brain anatomy, functional for living, functioning, dynamic brain imaging.
Two types of neuroimaging?Used for?
seconds or fraction of a second High temporal resolution Low spatial resolution
structural imaging high/low
minutes Low temporal resolution. High spatial resolution.
functional imaging high/low
Lesional study
Phileas Cage
Lack of contarast inside the scull.
Wilhelm Röntgen
radiography of the ventricles of the brain with the cerebral fluid replaced by air or radiopaque material or labelled with a radionuclide.
Used until 1970s
Risky!!
Walter Dandy
EEG
Electroencephalogrphy
Hans Berger (DE)
1924
EEG
1934 Epileptic spikes
1953 different stages of sleep
Combined with fMRI to be able to identify whole networks and brain regions involved.
Milestones of EEG
CT - computer tomography
[tomos: slice, section]
CT
CAT - computer axial tomography
X-ray CT
X-rays from many directions to reconstruct the volume of interest in slices
CAT, x-ray CT
Positron Emission Tomography PET
GAMMA rays.
Needs a cyclotron close by making the radioactive molecules. (Radioactivity lasts only for ~30 sec.)
PET
Magnetic Resonance Imaging MRI
DTI type of MRI, looking at microstructural changes
MRI
functional MRI
resting state fMRI / task-based fMRI
MRI
Multimodulling imaging
Often includes several MRI and a few fMRI
multimoduling imaging
EEG
Activity measured on a millisecond scale on the surface of the scalp.
Non-invasive
multiple electrodes
Portable and cheap (hat&gel&computer)
EEG
MEG - Magnetoencephalography
Measures magnetic fields
Head in a MEG helmet
Low spatial resolution-doesn’t reach to deep brain areas
High temporal, millisecond-level
tolerance, sticking ones head to a massive helmet-like machine, don’t move
MEG
PET - Positron Emission Tomography
Measures glucose metabolism
Glucose tagged using radiopharmaceuticals (tolerance highest)
fluorine - 18 (F-18)
fluorodeoxyglucose (FDG)
10-20 sec, mid temporal
whole brain mm scan good spatial
PET
functional near-infrared spectoscopy
BOLD
Difference between oxy-deoxyhaemoglobin (in colour)
Measures both oxygenation level and blood volume (excess of oxygenated blood after use/brain activity)
Spatial resolution: 2/4 low (surface 5 cm, small amount of sensors)
Temporal resolution: 3/4 high
Tolerance needed: low, suitable for babys
Works well for babies with their thin scull
fNIRS
Blood
Level
Oxygenation
BLOOD?Used in which techniques?Based on what?
fMRI - functional magnetic resonance image
Difference between oxy-deoxyhaemoglobin (in colour)
Measures both oxygenation level and blood volume (excess of oxygenated blood after use/brain activity)
Gives very detailed image
every few seconds, low temporal
tolerance needed medium, noisy
fMRI
Indirect:
fMRI - based on BOLD, magnetic differences between oxy-deoxyhaemoglobin. Oxygenated blood flooding after use.
fNIRS - also based on BOLD colour difference
Direct:
EEG
indirect-direct imaging
strong magnetic field:
deoxyhaemoglobin (Hhb) - paramagnetic
close to nothing magnetic field:
oxyhaemoglobin (O2Hb) - diamagnetic
magnetic
fMRI
30 000 (strong enough to lift up a car)
What technique:1.5 or 3 Tesla [machine]
MR - magnetic resonance
Wearing no metal in clothing or body.
Magnetic used in MRI scan is 30 000 stronger than earth’s magnetic field.
To check that someone is MR compatible?Why is this important
Comparing different stimuli -> activation in different brain areas.
Based on BOLD.
What is typically tested using fMRI?
Darker.
Brain activity sips first oxygen in from the nearby environment -> lots of deoxyhaemoglobing, more magnetic perturbation -> initial dip (dark picture)
Followed by overflow of diamagnetic oxyhaemoglobin –> less deoxyhaemoglobin than at rest -> less magnetic perturbation than at rest –> bright colour than t rest
BOLD
raw data
preprocessing
(‘clean up’: remove head movements, breathing, cardiac pulsation etc. increase the signal to noise to ratio)
single subject analysis
(general linear model GLM, fix head size etc to the template, where is the individual brain activity compared to experiment model)
group-level analysis
(compare groups, patients/healthy controls)
processing data
- A gene and its encoded protein (and different isoforms)
- how specific genes and proteins interact
- the signalling pathway and how it works
- the formation/ specification of cell types, tissues and organs
- the circuits and networks in the nervous system
- the above in relation to disease
What is studied with animal models? (
CHORDATA: animals in this category have notochords (not always a vertebrate). Frogs etc. also humans
ARTHROPODA: insects
HUMAN:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Hominidae
Subfamily: Homininae
Tribe: Hominini
Genus: Homo
Linnaeus, 1758
Chordata?Arthropoda?
500 million years
500 milj
Main reason:
understand causes, mechanisms, pathways from molecule to mind
Why study animals?
Homology
Homology
Homologous genes/proteins
Sequence identity between orthologous genes/proteins from different species
Genes homology
- mutating, inactivating or overexpressing a gene/protein
- finding interacting/ binding partners
- screening for enhancers/ suppressors
of ‘disease gene/protein’ - epistasis tests and manipulation of a signalling pathway
- targeted activation/ inactivation of neural circuits
- the regulation and function of behaviour
Methods
Genetic similarities between fly and mouse (and human)
Hirth & Reichert 1999
genetic similarities
Baker’s yeast has been used to discover genes and their function in the regulation of the cell cycle/cell division.
bakers/brewers yeast
eukaryotic cell
eukaryotic cell
cell division of bakers yeast
cell division yeast
TDP-43 and FUS genes has been discovered to be involved in the formation of motor neuron disease.
TDP-43 and FUS inhibit the growth of yeast cultures, they build aggregates = they are toxic.
Glucose = gene has been turned off
Galactose = gene has been turned on
TDP-43 and FUS
Form aggregates, means they are toxic.
Couthouis et al. (2011)
In human postmortem samples it is visible that human homolog of TAF 15 also forms aggregates in ALS cases, which stands for amyotrophic lateral sclerosis.
Couthouis et al. (2011)
TAF-15 and ALS
C. elegans
C. elegans
John Sulton 2002
Nobel Prize, C. Elegance
L1 - L4
a stage where larva can survive for 4 months, doesn’t mature into an adult.
larva, Dauer