University:
Binghamton University
Course:
BIOL 313 | Cellular Neurobiology
Academic year:

2024
Views:

116

Pages:

2
Author:

CrystalMintah

Anterior-posterior neural tissues One signal is retinoic acid- which causes neural tubes to develop posterior structures Retinoic acid activates homeobox or HOX genes which are responsible for anterior-posterior differentiation The neural tube also differentiates dorsal-ventral structures (neurons) within it Dorso-ventral differentiation begins as notochord secretes a signal-protein Sonic hedgehog or shh Shh diffuses dorsally towards the neural tube and triggers ventral most neural tube cells to make and release shh themselves So a gradient of shh is set up in the neural tube BMP$ is secreted by the epidermis above the neural tube. It is in high concentration at the dorsal neural tube and declines ventrally So in the neural tube, you have 2 gradients, BMP4 and shh What a neural tube cell differentiates into depends on the relative concentrations of BMP4 and shh Newly-made neurons may climb up a scaffolding Made of radial glia to move outward from the center of the tube Axon guidance: How do nelly formed neurons know which neurons to find, how do they get to them to find them and make connections Roger Sparry 1960s - Take FRog, loosen the eyeball in its socket, and rotate the eye 180 degrees so down is up and up is down - or the retina region that had been recovering input from the ground is now getting input from the sky: what does sthe frog see? - Frog world is upside down, Fod on the ground is interrupted to be up in the air, and frog misses the food with their tongue - So now: question is if axons from the retina need to regrow, will they correct for the inverter visual field? - It had the same rotation of the eyeball but cut optic nerve so axons had to find in the brain either: new connections that would correct the upside-down visual world or connect to their same old targets keeping the world upside down Result: The world remained upside down, meaning the neurons reconnected to their old targets, recognized these, and found them Not specific channels that each ganglion and brain cell use to recognize each other It is a : In brain there is a gradient of ephrin