NEUR533 - Wiring the Brain Flashcards
Learning outcomes
Review lateral geniculate nucleus and ocular integration - 12 layers from neurobiology and neuroanatomy
Wiring of the brain neuroanatomy and neurobiology - KNOW AND REMEMBER
NEUROGENESIS - radial glial cells
What cells give rise to neurons in astrocytes (neurogenesis cell proliferation) in the cerebral cortex?
Radial glial cells
What are the 2 proteins for transcription factors and cleavage plane during cell division to determine fate of daughter cells, in radial glial cells?
Notch-1 & numb
REVIEW CELL MIGRATION PROCESSES
What direction do pyramidal cells and astrocytes migrate from the ventricular zone?
Vertically
What type of fibres do pyramidal cells and astrocytes utilise to migrate from the ventricular zone?
Thin radial glial fibers
What direction do inhibitory interneurons (e.g. GABAergic neurons)and oligodendroglia move for cell migration?
Laterally/horizontal
What is the first layer cells migrate to take up residence?
Subplate layer - eventually disappears
Where do the next cells go to divide migrate to? (2nd stage)
The cortical plate
The first cells to migrate and arrive at the matrix become what layer?
Layer VI (bottom layer)
Followed by V, IV, III and so on e.g. “inside out”
Review cell differentiation process
Differentiation of cortical areas
What are the 3 phases of pathway formation?
Pathway selection
Target selection
Address selection
What information is processed in he medial geniculate nucleus?
Auditory signals
What info is processed in the lateral geniculate nucleus?
Visual stimuli
What is a growth cone?
The growing tip of a neurite
What are the 2 ‘feelers’ of neuronal tip growth and pathway formation?
Lamillipodia
Filopodia
What are the 2 core molecules that are interacting within the Folopodia extracellular matrix? (neurites)
Laminin and integrin molecules
Axon guidance
Tehy are all about chemo communication
Axon Guidance
Growth guidance cuies
What is the growth guidance cue chemoattractant?
Netrin
What is the growth guidance cue chemorepellant?
Slit
Robo is the receptor
What are the factors guiding retinal axons to tectum?
Ephrins/eph (repulsive signal)
Who came up with the chemoaffinity hypothesis in the 1940s?
Sperry
Retinotectal projection in frogs
Excellent research in the role of retinotopic mapping
Neuromuscular synapse
MUST LEARN THE FORMATION OF CNS SYNAPSES
What is the first step of CNS formation of synapses?
Dendritic filopodium contact axon
What is the 2nd step of CNS formation of synapses?
Synaptic vesicles and active zone proteins recruited to presynaptic membrane
What is the 3rd step of CNS formation of synapses?
Receptors accumulate on postsynaptic membrane
LEARN THE ELIMINATION OF CELLS AND SYNAPSES
Sunapse elimination in the neuromuscular junction
Activity-dependent synaptic rearrangement
Segregation of retinal inputs to teh LGN
- fine tuning
- based on retinal waves
-
Striate cortex - uses radio tracers to find ocular dominance columns
What did monocular deprivation experiments show us?
- Ocular dominance shift
- Plasticity of binocular connections
- Synaptic competition
Ocular dominance shift
- #3 is max convergence - Binocular vision
youtube to understand
Strabismus - lazy eye
odulatory influences on cortical circuits
What are 3 key factors for modulatory influences on cortical circuits:
_ retinal activity before birth
- visual environment after birth
- enabling factors e.g. Ach - glutamate
Synaptic plasticity
What are the 2 glutamate receptors for excitatory synaptic transmission?
AMPA receptors (ion gated)
NMDA (unique properties)
What are the 2 unique properties of NMDA receptors?
Voltage gated ion channel owing to to action of Mg2+ (ligand and voltage gated e.g. double gated)
- Conducts Ca2+
- High and low Ca2+ levels are key
Long term potentiation with NMDA receptors
Strong NMDA receptor activation =
Strengthening of synaptic transmission (LTP)
_____ entry throgh the NMDA receptor channel triggers the biochemical mechanisms that modify ____ effectiveness
Ca2+
Synaptic
What is the long-term depression associated with:?
- Neurons firing out of sync ‘lose their link’
- Loss of AMPA receptors
- Synaptic pruning
- Key in teenage years
Deprivation leads to reduced visual responsiveness.
What are 3 hypotheses why plasticity diminishes after critical periods (e.g. teens, young adults aged 21)
- When axon growth ceases
- Synaptic transmission matures
- Cortical activation is constrained
Is intrinsic inhibitory circuitry late to mature?
Yes
What does understanding the development regulation of plasticity help recovery from what?
CNS damage
Summary
