Lecture 18 - Circuit Construction II Flashcards
What is John Langley known for studying?
He’s known for studying the sympathetic pathways associated with the “fight or flight” response, like pupil dilation and blood vessel constriction. He studied through working with the superior cervical ganglion (anterior-most sympathetic ganglion).
What happened when Langley stimulated the T1 and T4 preganglionic fibers?
Stimulation of T1 (thoracic level 1) preganglionic fibers coming from the spinal cord activate postganglionic neurons that cause pupil dilation in the eye. Simulation of T4 (thoracic level 4) preganglionic fibers activate postganglionic neurons that cause constriction of blood vessels of the ear.
Axons from T1 and T4 run together in the same bundle to the ganglion. What does this indicate?
This indicates that there is an organization of connections in the ganglion that allows for specific behaviour effects.
What did Langley find would happen when the cervical sympathetic trunk was cut?
He found that the injured sympathetic nervous system could regenerate following this cut. Behaviour responses would be lost upon cutting but could be re-established within a few weeks despite the ganglion having a mixed population of postganglionic targets.
Despite the superior cervica ganglion having a mixed population of postganglionic cell targets, selective responses could be re-established within a few weeks after injury (cervical sympathetic trunk cut). What does this indicate?
This suggested that neurons make selective choices for their partners and connections.
What layers of cells (in order) must light pass through in order to reach the photoreceptors in the retina?
Light must pass through ganglion cells, amacrine cells, bipolar cells, and horizontal cells.
How do sidekick 1 and 2 proteins contribute to synaptic organization in the inner plexiform layer of the retina?
Cells on each side of the IPL (from ganglion cell layer and inner nuclear layer) meet up in different layers of the IPL depending on which proteins they are expressing. For example, sdk-1 expressing cells meet in layer S4.
Suppose you take a SP+ INL cell and cause it to also express sdk-1. What type of GCL cell will it connect with, and in which IPL layer?
The cell will connect with a normal sdk-1+ cell in the S4 layer (normal layer for two sdk-1+ cells).
Which 4 CAMs are involved in homophilic adhesion in the retina IPL?
Sidekick-1, Sidekick-2, DscamL, and Dscam
What are basket cells?
Basket cells are inhibitory interneurons that form basket synapses near the axon initial segment of Purkinje neurons.
What would happen in a mutant with ankyrinG knocked out?
The basket cells would not form inhibitory synpases at the AIS of Purkinje cells.
Where is ankyrinG most concentrated?
AIS of Purkinje Cells
What is used for synapse targeting of basket neuron axons to Purkinje neurons of the cerebellum?
Targeting is mediated by oligomeres of neurofascin with ankyrinG.
What are the two options for an axon once it settles on a target?
It can form a synapse or retract/degenerate.
What is a motor unit composed of?
A motor unit is composed of a motor neuron and the muscle fibers it innervates.