Target Selection

Target Selection - Innervation of the Inner Ear is...

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Target Selection: Axon Targeting: axon reaches the target area and then sends out filopodia to find the right partner and then it forms synapses Growth Cones change in target zones: - axon slows down in target zones and then branches out to make synapses - tectum has low levels of FGF2 - high levels of FGF2 in tectum will not be a suitable environment for retinal axon so it keeps going Defasciculation is Regulated by Beat Proteins: - Beat 1 mutants have no defasciculation - axons are fasciculated because beat 1c binds the beat receptor - in target area, beat 1a binds to the beat receptor which prevents beat 1c from binding to the beat receptor which breaks adhesion so that the axons can defasciculate - so double mutant (both beat 1c and 1a) has normal defasciculation NT3 guides Superior Cervical ganglion (SCG) axon to external ear - NT3 = important for SCG neurons to innervate the target pinna
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Unformatted text preview: Innervation of the Inner Ear is regulated by BDNF and NT3-double mutants – inner ear = uninnervated -BDNF in NT3 region = cochlear becomes innervated by vestibular part of ganglion Secondary Targets: Visual and Auditory Targets Share Similar Cues-EphrinA2/EphrinA5 define the border between LGN and MGN Target Specific Regeneration-SCG = superior cervical ganglion -Different SCG secret specific signals to attract T1 or T4 to reinnervate the right target even after you cut it SCG and T5 are targets of anterior and posterior spinal roots Transplant T5 into SCG and the more posterior roots innervate T5 (specificity between axon and their target) Sema III is expressed in VENTRAL SPINAL CORD and it REPELS axons of CGRP (calcitonin gene related peptide) neurons Maladptation-tectum = eye-page 2 FROG eye CUTTING experiment! -...
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This note was uploaded on 08/26/2011 for the course BIOL 426 taught by Professor Profgongchen during the Spring '08 term at Penn State.

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