Topographical organization. Dorsal projects to ventral and vice versa. Anterior projects
to posterior and vice versa. Image is mapped similarly in tectum as it is in world.
Roger Sperry experiments. Transected the optic nerve. Saw that it rewired
What is axon guidance?
Need reliable intricate wiring of axons. If look in model systems like C. Elegans, they are
small. Can identify every single cell in these systems and their targets. High fidelity
Why is axonal
Neuron Target Interactions
Neurons make many synapses with each other and with other non-neuronal cells.
Image shows pyramidal neuron with long processes. Thick processes are stained with
GluR1 (on the post-synaptic area) and red shows synaptophysi
Programmed cell death. Example of hand, "paddle" created, and then cell death occurs
to create digits. Genetic program that directs the development of mammals. They are all
different. The basic program underlying development is the same, however. Could ha
What causes dorsal/ventral axis?
First event that occurs is the induction of the floorplate in the ventral part and the
roofplate in the dorsal part. The floorplate is made of specific glia. The notochord under
the neural tube in the embryo secrete
How to progress from a two cell organism to a fully developed embryo?
Determination of cell fate. When the organism is growing, need to determine which
parts of the embryo will give rise to different systems.
Cell proliferation, more cells to get o
Nervous system divided into central and peripheral nervous system. Specific neurons
that can gather information from the external environment, process, and send to
sensory nervous system. DRG send information to the spinal cord for instance. Then to
Axon conduction speed
Action potentials. The way through which information is transmitted down the axon.
Important for communication between neurons in the nervous system. They are all or
none. Passed from one cell to the next cel. The speed a
Neuronal Polarity, Neurite Outgrowth, Dendrite Morphogenesis
Dendrites on one side of the cell and axon on the other. Common polarity.
Also can have dendrites coming off the axon.
Can also have sensory terminals which are not necessarily post synaptic. Ce
How do we switch things off in space and time? If cues exist, why are they not on
constitutively? How can axons change their response to the same cue in their
environment over space and time?
Example questions for the exam:
Neuronal cell body with axon co
Two phases of synapse formation
Today we will discuss address selection where the axons are refined. An activity
dependent process that will continue in the adult life in the hippocampus and the
olfactory system. Neurons