L16

Question 1

[fly] axons of SNs project TO CNS based on…

Answer 1

…location of neuronal cell body in periphery (lateral VS ventral) (location not modality); A2- axons from all dorsal and lateral SNs project to CNS in intersegmental nerve (e.g.Ich5; axons from all ventral SNs project to CNS in segmental nerve (e.g.vcA, vcB)

Question 2

[fly] axons of SNs project WITHIN CNS based on…

Answer 2

…modality (ext. sensillum VS chordatonal; due to proneural expression of axon guidance Rs; es (mech)= ASC = no Robo3 expression thus not repelled by Slit at midline; eh (prop) = ATO = Robo3 expression thus repelled by Slit at midline (lateral arbor)

Question 3

During metamorphosis…

Answer 3

…most larval SNs degenerate, 1 remains per pathway to guide adult specific Ns (adult specific Ns follow neuromere; Wing and Haltere follow dorsal ISN to form Wing and Haltere nerves; legs follow ventral SN to form leg nerves; once target reached, neurons segregate based on modality, chemo terminate in ventromedial layer of leg, mech in surrounding neuropile, prop in layer surrounding mech

Question 4

Axons of particular modality terminate in…

Answer 4

…in neuropile in topographic map that relates to the location of the neuronal cell body in the periphery (spatial mapping)

Question 5

[mouse] Ventral sensory spinal afferents in the DRG show…

Answer 5

…similar organisation to projections to CNS

Question 6

[mouse] Misexpression of Runx5 in nociceptive neurons causes them to…

Answer 6

…project to more ventral instead of dorsal domains despite normal neuronal identity (thus most mammalian systems are topographic)

Question 7

[mouse] How well is the spatial map preserved?

Answer 7

At all levels of processing

Question 8

Mapping in isocortex is established by…

Answer 8

…FGF8 and EMX2 gradients; increased EMX2 shifts maps rostrally; altered FGF8 expression shifts map; ectopic FGF8 causes duplication of SI

Question 9

Visuotopic…

Answer 9

…complementary gradient of (retina)EphA:EphrinA(tectum) [temporonasal->anterioposterior] and EphB:EphrinB [dorsoventral->mediolateral]

Question 10

Olfactory in mammals…

Answer 10

… is R based; each R maps onto 1/2 glomeruli out of 800 in olfactory bulb (ORs also axon guidance molecules)

Question 11

Olfactory in flies…

Answer 11

…spatial map in antennal lobe