Development p2 Flashcards

Question

In what ways can ligand binding to recptors affect growth

Answer 1

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

Answer 2

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

Answer 3

Pioneer axons- act as scaffolds for later-arriving axons | Respond to molecular cues along the way

Answer 4

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

Answer 5

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

Answer 6

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

Answer 7

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

Answer 8

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

Answer 9

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

Answer 10

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

Answer 11

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

Answer 12

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

Answer 13

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

Answer 14

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

Answer 15

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

Answer 16

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

Answer 17

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

Answer 18

In LGN, segregation of input is complete before birth

Answer 19

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

Answer 20

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