Axon Guidance Part 1

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What is the primary function of the retinal ganglion cells in the visual system?

To process visual cues and interpret visual information
To regulate the amount of light entering the eye
To transmit visual information from the retina to the brain (correct)
To convert light into neural signals

How many decision points do axons make during their journey to the optic tectum?

Exactly 10
At least 10 (correct)
Only 2
At least 5

In mammalian nervous systems, what percentage of axons cross over at the optic chiasm?

Some axons (correct)
All axons
Half of the axons
None of the axons

Which part of the retina projects to the ventral tectum or the lateral superior colliculus?

Dorsal RGC (C) Signup and view all the answers

What is the purpose of the experiment involving fluorescent tagging of cell bodies in the retina?

To test the retinotectal pathway and topographic targeting (A) Signup and view all the answers

In which organisms is it observed that all axons cross over at the optic chiasm?

Amphibians and chicks (A) Signup and view all the answers

What is the primary function of the growth cone in axon guidance?

To read cues in the environment and dictate the direction of axon growth (D) Signup and view all the answers

What is the role of F-actin arcs in the transitional domain of the growth cone?

To act as barriers for microtubule growth (D) Signup and view all the answers

What is the primary force driving axon extension in the growth cone?

The degree and extent of actin polymerization (A) Signup and view all the answers

What is the fate of many axons that initially project past their target?

They loop back or extend a collateral branch (C) Signup and view all the answers

What is the role of the peripheral domain of the growth cone?

To guide pioneer microtubules along F-actin tracks (C) Signup and view all the answers

What is the function of ADF/cofilin in the transitional domain of the growth cone?

To sever actin filaments into a pool of actin monomers (B) Signup and view all the answers

What is the result of inhibiting actin polymerization with cytochalasins in the growth cone?

Growth cone movement and extension is arrested (B) Signup and view all the answers

What is the relationship between the location of RGCs and their target in the Superior Colliculus?

Dorsally located RGCs target the ventral SC, and ventrally located RGCs target the dorsal SC (C) Signup and view all the answers

What is the main difference between the Random Outgrowth Theory and the Chemoaffinity Hypothesis?

The Chemoaffinity Hypothesis suggests that axon guidance is based on chemical tags, while the Random Outgrowth Theory suggests it is based on physical restraints (C) Signup and view all the answers

What was the result of Roger Sperry's experiment where he cut the optic nerve and rotated the eye 180 degrees?

The regenerating axons formed connections in the same region of the tectum as before the optic nerve was cut (D) Signup and view all the answers

What is the significance of the 'critical period' observed in Roger Sperry's experiment?

It is the period during which the eye can be rotated and the retinotectal map will still be normal (C) Signup and view all the answers

What is the conclusion from the experiment where the eye was rotated 180 degrees?

Connections in the adult retinotectal pathway are not determined by experience (D) Signup and view all the answers

What is the role of local cues in the neuroepithelium in the formation of the optic tract?

They guide the formation of the optic tract by providing chemical cues (D) Signup and view all the answers

What is the behavior of retinal axons at the optic chiasm?

They grow towards the part of the graft that was originally caudal (A) Signup and view all the answers

What is the effect of microtubule stabilizers on a specific side of the growth cone?

Turning towards that axis (B) Signup and view all the answers

What is the result of enduring coupling between microtubules and F-actin?

Microtubule translocation by F-actin retrograde flow (C) Signup and view all the answers

What is the effect of cytochalasin B on actin filaments in the growth cone?

It prevents actin polymerization (D) Signup and view all the answers

What is the role of adhesions between the growth cone and ECM?

To latch and maintain traction (A) Signup and view all the answers

What is the mechanism of filopodial advance in the growth cone?

Actin polymerization at the leading edge (D) Signup and view all the answers

What is the result of a loss of F-actin from the periphery of the growth cone?

Growth cone collapse (C) Signup and view all the answers

What is the role of the lamellipodia in the growth cone?

To contain cross-linked F-actin filaments (A) Signup and view all the answers

What type of adhesion is involved in axon fasciculation?

Fasciculation (B) Signup and view all the answers

What is the function of a soluble inhibitory molecule in axon guidance?

To repel the axon (A) Signup and view all the answers