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Neurophysiology > Development p2 > Flashcards

Development p2 Flashcards

1
Q

What is the result of alcohol when pregnant

A

Reduced proliferation of progenitor cells, increased cell death in VZ
Small brain volume

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2
Q

What is the result of cannabis when pregnant

A

Feotal growth restriction, mental dysfunction (memory impairment, social difficulty)

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3
Q

What is the result of cocaine when pregnant

A

Inhibits tangential and radial migration, long-term consequences for DA transporter function

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4
Q

In what order are different combinatorial transcriptino codes expressed

A

Reelin, Tbr1, SCIP, GABA, Brn2

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5
Q

What transcription factor speciices supragranular layer neurons

A

SATB2

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6
Q

What transcription factor speciices layer 5 neurons

A

CTIP2

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7
Q

What transcription factor specifices subplate neurons

A

SOX5

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8
Q

Where are growth cones

A

Tip of advancing axon

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9
Q

What is netrin

A

A diffusible molecular guidance molecule- atrracts some neuronal populations and repels others

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10
Q

Axons extend well past their targets during development and then…

A

Form collaterals that connect with their target

Excess length/colaterals are then eliminated through degeneration

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11
Q

An example of large-scale axon elimination

A

Develops area-specific projections of layer 5 neurons of the neocortex

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12
Q

What happens to our proportion of grey vs white matter as we get older

A

Less grey matter as we grow from age 4-21

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13
Q

What difference in gray vs white matter happens in schizophrenia

A

Dynamic wave of accelerated gray matter loss

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14
Q

Environmental prenatal factors associated with schizophrenia

A

Maternal nutrition and infection, season of birth, urban birth, small head size

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15
Q

Summarise how ocular dominance columns are formed

A

The 2 monocular inputs are initially overlapped, and gradually segregate by selective local pruning driven by competition betweeen correlated neural activity

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16
Q

How do glutamatergic cells migrate

A

Radially from ventricular zone to cortical plate

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17
Q

How do GABAergic cells migrate

A

Tangentially from the ganglionic eminence to CTX

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18
Q

What results from leading edge extension defecits in cell migration

A

Mixed up collectino of cells that don’t leave the subventricular zone- paraventricular heterotopia

19
Q

What is type 1 lissencephaly

A

Subplate and preplate split properly, but superficial layers pile up- partially developed cortex

20
Q

What is type 2 lissencephaly

A

Cells don’t stop migrating outwards past the pial membrane,shape of brain altered

21
Q

What is the result of a defective reelin pathway

A

Subplate and marginal zone don’t split into layers, but stay together as a super plate, cortical plate develops in a backwards outide-first fashion

22
Q

What is the subplate

A

Subplate cells are very important as a dynamic scaffold during devellopment, but die off and aren’t present in the fully developed in the fully developed brain

23
Q

In what 3 ways can growth cones be powered

A

By movement of actin along myosin
By assembly of actin monomers into polymeric filaments
By slowing depolymerisation of actin filaments

24
Q

What molecule in the growth cone drives it forward

A

Microtubules flow from the central core into the newly extended tip

25
Q

In what ways can ligand binding to recptors affect growth

A

Stimulates formatino of second messengers that affect cytoskeletal organisation
Regulating Ca2+ conc, motility is optimal within a narrow range of conc
Modulating enzymes that regulate proteins that regulate actin polymerisation

26
Q

What is the idea of molecular matching

A

Recognition between axons and their targets relies on molecular matching- usually pairs of ligands along the pathway and receptors on the growth cone

27
Q

How can we describe the first axons travelling up the optic nerve to the brain

A

Pioneer axons- act as scaffolds for later-arriving axons

Respond to molecular cues along the way

28
Q

What protein-ligand combo can act by forming gradients to guide axonal growth

A

Eph kinases are receptors, ephrins are membrane-associated ligands
eg ephrin-A proteins bind and activate EphA kinase

29
Q

What map to ephrins and Eph kinases set up

A

Retinotopic map in the tectum

eg ephrinA grades from anterior-low to posterior-high in the tectum, counter Eph receptor gradient in the retina

30
Q

How can inappropriate targets be turned into appropriate ones in skeletal muscle

A

Motor axons can convert the target muscle fibre into an appropriate type before the fibre’s properties are fixed eg slow -> fast by the axon’s firing

31
Q

What are the possible benefits of initial polyneuronal innervation

A

Ensures all muscle fibres are innervated, allows all axons to capture an appropriate set of target cells, means activity can change the stregnth of specific synaptic connections

32
Q

What is likely to determine the outcome of synapse competition in muscle fibres

A

The total amount of synaptic that the axon provides the muscle with- when a fibre is not very active, it is likely to withdraw, and redistribute its resources

33
Q

What cooperative firing is likely to establish ocular dominance columns

A

Neighbouring axons from one eye tend to fire together (activated by same stimuli), so cooperate in depolarising a target cell, strengthening these synapses at the expense of non-cooperating synapses

34
Q

Hubel and Wiesel experiment about temporal activity affecting competition vs cooperation

A

Made cats strabismic- binocular cells became monocular instead, suggesting disrupting the synchrony of inputs led to competition rather than competition

35
Q

Where do the first physiological changes occur following closing of one eye

A

In layers II/III and V of V1 (local circuitry), rather than thalamic input- suggests loss of cortical responsive results from circuit alteration NOT loss of input

36
Q

What 3 changes of cell functino have been suggested as underlying the circuitry changes in V1 durnig optical deprivation

A

Excitatory synapses decrease in strength (LTD)
Inhibitory synapses become stronger, decreasing the level of excitation caused by closed eye input
Turning the circuit to favour LTD

37
Q

What neurotransmiter signalling appears inolved in monocular depviration

A

The critical period for changes from deprivation can be advanced by enhancing GABA signalling, and delayed by delaying GABA signalling

38
Q

What is the appearance and loss of dendritic spikes thought to reflect

A

Formation and elimination of synapses- increased spine no is associated with behavioural changes

39
Q

Describe the progression of dendritic spikes during monocular deprivation /remapping of stronger eye

A

Spine no increases 2 days after eye closrure, suggesting synapses are rearranging
Spine no decreases due to loss of inputs from closed eye
Spine increase occurs as responsiveness to open eye increases

40
Q

Example for how alteratinos in V1 synaptic strength may affect V1 input from LGN?

A

V1 activity may regulate the secretion of BDNF (brain deprived neurotrophic factor), which enhances thalamocortical growth and speeds up maturatino of inhibitory circuits, regulating axonal survival

41
Q

What physiological change may underlie the closing of the critical period

A

Myelination of axons occurs when the critical period closes- creates physical barriers to sprouting and axonal growth, and contanis factors like Nogo that inhibit axonal growth

42
Q

How does segregation of retinal input in the LGN differ from that in the cortex

A

In LGN, segregation of input is complete before birth

43
Q

How does segregatino of LGN input occur in utero

A

Retinal neurons fire spontaneously, with neighoburing ganglion cells firing in synchronous bursts
These bursts spread across the retina as waves, exciting a local group of LGN neurons, strengthening these synapses at the expense of others

44
Q

How does the pattern of activity on the light refine the topographic map on the tectum

A

When light falls haphazardly on the retina (as normally), it produces local synchronous activity of neighbouring ganglion cells- the tectum deetrmines which retinal axons are neighbours by judging which fire in synchrony

Neurophysiology (23 decks)

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