Lecture 20 - Regeneration and Plasticity of CNS Flashcards
How is cortical organization mediated?
mediated by activity-dependent competition early in life
What determines which neurons survive?
neurotrophic factors
How does the elimination of neurons and synapses occur?
1) An alpha motor neuron innervates multiple immature muscles
2) Following maturation, a single alpha motor axon innvervates one muscle fiber
What happens if there an AChR blockade in a neuromuscular junction?
- will result in a loss of AChRs at the site of blockade
- and a withdrawal of axon branch at site of AChr blockade
What happen to the axon if the AChR blockade occurs on the nerve?
- there will not be a complete loss of the axon
- no activity on the axon does not make you lose innertivity (there must be activity)
What is synaptic rearrangement?
- Changes in the innervation pattern Before and After Birth
- Consequent of neural activity and synaptic transmission
What is the cause of segregation of retinal input into the lateral geniculate nucleus?
spontaneous activity in ganglion cells
What is the pathway of vision
1) Input goes in the eye
2) Goes down the optic nerve
3) Continues into the optic tract until it reaches the Lateral geniculate nucleus
4) It then goes into the visual cortex of the left cerebral hemisphere where it goes from layer 4 to 2 & 3
Does segregation of the lateral geniculate nucleus occur before or after the development of photoreceptors?
Before
Describe spontaneous activity of ganglion cells
- waves of activity coming in, while in the womb, from the right or left eye.
- First, the activity only goes through the same region (Right or left) but segregates during development
What is the Hebbian modifications?
- When there are ganglionic waves happening in one eye and there’s a mix of input on both sides (left and right eye).
- But when being fired, the input is only reacting on one side until synaptic modification occurs and they are segregated
- input comes from synaptic waves or activity within the ganglion cell in the womb
When layer 4 receives input, where do they send their axons?
Layer 2 and 3
Explain an experiment of binocular vision discovery in response to neurons in the primary visual cortex of a monkey to visual stimuli
- Did their study by using a light that crosses the contralateral or ipsilateral eye. Recorded single corticoid neurons
- Found that cortical cells only (or more) get input from contralateral and others only (or more) get input from ipsilateral eye and some from both eye
According to the experiment of the response of neurons in primary visual cortex of a monkey to visual stimuli, what happened when the contralateral eye was closed?
only ipsilateral cortical cells got input BUT, you still get input from both eyes in the Lateral Geniculate Nucleus
What happens to the dominance shift and modulatory input when you cut a part of the basal forebrain complex? or locus coeruleus
- The ocular dominance remains the same, suggestion that input is coming in from other regions of the brain (there are other networks)
What happens to the dominance shift of an animal asleep under anesthesia?
when asleep there is no dominance shift but still some inputs being received
What are the two generation of brain development circuitry
1) Placement of wires before birth
2) Reorganization/loss of synapses during infancy
What happens when an amputation occurs at the third digit?
Brain receives input from D2 and D4 where digit 3 got amputated. D2 and D4 take over and utilize that area
What is the Phantom Limb Sensations
Perception of sensations that come from amputated limb.
How does a Phantom Limb Sensations occur?
The sensations occur from stimulation of regions whose somatotopic representation border the missing limb .
