Methods to Study NDDs Flashcards
Give examples of NDDs
- intellectual disability
- communication disorders
- autism spectrum disorder
- ADHD
- neurodevelopmental motor disorders
- specific learning disorders
- schizophrenia
What are the DSM-5?
a group of conditions with onset in the developmental period, inducing deficits that produce impairments of functioning
What causes neurodevelopmental disorders?
disruption of formation of neuronal networks
What causes neurodegenerative disorders?
disruption of established neuronal networks
What is the time of onset of degenerative disorders?
after neuronal circuits have been formed
Give examples of degenerative disorders
- AD
- PD
- HD
Give examples of developmental disorders
- autism
- ADHD
- anxiety disorders
What does the time of onset of developmental disorders correlate to?
development of the brain
Which developmental stages are affected by neurodevelopmental diseases?
- neurogenesis
- neuronal migration
- neuronal differentiation
Which biological processes are affected by neurodevelopmental diseases?
- regulation of protein synthesis
- regulation of transcription
- epigenetic regulation
- synaptic signalling
Give examples of common themes between human NDDs
changes in neuronal networks and synaptic function
What are synaptopathies?
brain disorders with underlying synaptic dysfunction that result from alterations in intrinsic synaptic molecular mechanisms
What are causes of synaptopathies?
- mutations of synaptic genes
- mutations of genes involved in neuronal and synapse development
What are the 8 steps of synaptic transmission?
- synaptic vesicle loading
- docking
- priming
- vesicle fusion
- clathrin-mediated endocytosis
- uncoating
- endosome fusion
- synaptic vesicle reformation
What does the postsynaptic density do?
mediate clustering of receptors and cell-adhesion molecules and orchestrate the coupling of diverse signalling components
Give examples of implicated presynaptic genes
- synapsins
- synaptophysin
- piccolo
- SNAP25
- cadherin
Give examples of implicated postsynaptic genes
- neuroligin 3 and 4
- neurexin 1
- ApoE e4 allele
- calcineurin
What are dendritic spines?
tiny protrusions from dendrites, which form functional contacts with neighbouring axons of other neurons and receive input from one excitatory synapse
What do dendritic spines do?
- implement input-specific synaptic plasticity
- enhance synaptic connectivity
- modify synaptic potentials
What do dendritic spines represent?
excitatory postsynaptic compartments
What is synaptic pruning?
he process in which the brain removes neurons and synapses that it does not need (normally happens between age 2-10)
What changes in neuropsychiatric disorders?
spine density
What do changes in spine density affect?
neuronal networks
What do guidance cues do?
wire neurons into networks
What is the first step in studying synaptopathies?
identifying the genes involved
How can specific genes be identified?
- forward genetics (mutagenesis, positional cloning)
- reverse genetics (ectopic expression, gene silencing, gene targeting)
- GWAS
- whole genome sequencing
Give examples of models used to study synaptic disorders
- 2D cell cultures
- C. elegans
- drosophila
- zebrafish
- mouse
- human organoids
Give examples of methods used to study synaptopathies
- synaptosomes/synaptoneurosome isolation
- neuropil microdissection
- axon-TRAP
- fluorescent activation cell sorting for synaptosomes
- puromycin proximity ligation assay
- expansion sequencing
Give examples of microscopic strategies for studying synapses
- enumeration of spine density and morphologies
- investigation of synaptic marker distribution
- investigating nanoscale synaptic organisation
- whole cell / single synapse imaging of synaptic transmission
- electrophysiology
How can axons and dendrite development be viewed?
Sholl analysis
What happens during Sholl analysis?
concentric ircles are superimposed on the dendritic processes and at each point of intersection, the number of crosses is counted to produce a plot
What do brain organoids do?
capture the key features of human brain development and organisation
What can brain organoids be used for?
precision medicine
What are the limitations of organoid technologies?
- cellular components
- standardisation
- costly
- scalability issues
- heterogeneity
- lack of output compared to whole organisms
