Building neural circuits II Flashcards
(28 cards)
Identify 3 steps to synaptogenesis
- axon guidance
- cell to cell interaction
- syanpse maturation
What is a growth cone?
specialised highly dynamic structure at distal tip of growing axon
Define the term corticofugal
- nerve fibre that originates in cerebral cortex
Define the term corticocortical
- neurones that star in one cortical region and ends in another
What are the two types of cues in axon guidance
- substrate bound
- diffusible cues
Describe substrate bound cues [6]
Adhesive
- act as roadway
- CAMs and ECMs
Repellent
- roadway guard rails
- slots/ephrin and and chondroitin sulphate proteoglycans
Describe diffusible chemotropic cues [4]
- roads signs
- chemoattractive and chemorepulsive
- lead to cytoskeleton modulation
- entrains/morphogens/NTs/transcription factors
What is netrin -1
major guidance molecule for axon growth cones
For each condition state the result
1. Netrin
2. Inactive netrin
3. Netrin + netrin inhibitor
- axons grow in direction of netrin
- grows straight, not in direction of netrin
- opposite direction to netrin
What are synaptic organisers [3]
- cell adhesion molecules
- on cell wall of neurones
- interact tot form synapses
Describe cell to cell interaction in synapse formation [4]
- cell adhesion molecules interact
- can be homophilic or heterophilic
- play cohesive molecule
- initiate trans-synaptic signalling for synaptic differentiation
What evidence is there for neuroligands in synaptogenesis [3]
- nothing (control) vs with neuroligin expressed fibroblasts placed in culture
- neuroligin+ synapses were formed
- neuroligigin promoted presynaptic organisation
Describe pre-synaptic specialisation [4]
- modulation of presynaptic protein function
- activation of intracellular signalling
- active zone organisation
- increased efficacy of NT release
Describe post synaptic specialisation [2]
- recruitment of scaffolding proteins
- incorporation of clusters of receptors
What is the importance of synapse-specific molecules [3]
- allows for diversity during modulation
- to form excitatory and inhibitory neurones
- allows for synapse specificity
- Label the diagram
see diagram
Conditional deletion of in Cbln4 SST interneurones will result in….
reduction of SST synapses on dendrites
Overexpression in Cbln4 in SST interneurones will result in….
increase in SST synapses of dendrites
Overexpression of Cbln4 in PV+ basked cells results in …. and….
- no change in PV synapses on soma
- increased PV synapses on dendritic synapses
Describe synaptic pruning within the brain [4]
- number of spines decreases with ages
- large decrease during puberty
- time of significant decrease varies between different cortical regions
- pFC seen latest in age
Which neurones are associated with the regulation of synaptic pruning [2]
- microglia
- astrocytes
What is meant by ‘synaptic protein is activity dependent’ [2]
- the amount a neurone is fired
- will effect the pruning that occurs there
Define the term critical period [5]
- time window when brain circuits are actively shaped
- by environmental inputs (experience)
- cortex is most plasticity
- sensory and cognition abilities are acquired
- neural circuits matured
Describe the critical period for binocularity (evidence) [6]
- layer III V1 receives inputs from both eyes
- when light shone in eyes
- rodents have bias fro contralateral eye in binocular zone
- when contralateral eye is covered during critical period in mice (3-5days)
- increased neurones respond to ipsilateral eye
- when in adult mouse
- do not see shift to use ipsilateral eye
