3 - Brain Circuits Flashcards
Genetic blueprint
Initial establishment of brain circuits.
Basic circuits
Initially established by molecular cues guiding axons to their targets.
Neurite
Extending axon
Filopodia
Extended and retracted from…Lamellopodia by the polymerization and depolarization of actin.
Once axon is moving in the right direction microtubule subunits:
Bind together to solidify extending axon.
Axons are guided along they way by:
1) Contact-mediated repulsion
2) Chemoattraction
3) Chemorepulsion
Axons are guiding to their final destination by:
Specific trophic support (NT3- muscle spindles)
Fox P1 mutant…
Over expression of neurons
Initially over expressed
Too numerous
Too many connections
Pruning
Finally stages of development, excessive neurons and connections pruned away
Example of motor system
Muscle fibers initially receive input form multiple motoneurons in the SC, reduced to 1 motoneuron per muscle cell before birth.
Experience-dependent plasticity (2)
1) Unsupervised learning
2) Supervised learning
Unsupervised learning
Organism just gathers info from the environment
Supervised learning
Organism interacts with a tutor to perform specific actions
Birdsong
Juvenile learns to replicate tutor by repeated practice. Spectrogram quantifies sound characteristics. Neural circuits specific to songbirds encode behavior. Bird is using auditory feedback to adjust pitch.
Ocular dominance columns are formed of:
Experience-dependent plasticity
- Without light shining on eyes at specific times in development plasticity won’t occur
Right visual field is represented in which visual cortex?
Left
Right visual field comes form which eye(s)?
Both left & right
Cells in the Left visual cortex receives input from which eyes?
Both left & right
T/F. The neurons in primary visual cortex that responds to the left eye are somewhat spatially segregated form the neurons that responds to the right eye.
True
T/F. Neurons representing one eye cluster together into bands (ocular dominance columns) which alternated w/ bands of neurons representing the OPPOSITE eye.
True
What does the Ocular Dominance Columns depend on?
Presence of light on the retina during critical periods pf development.
Is the purpose of the Ocular Dominance Columns known?
No, it may simply be an example of critical periods in development that apply to other neural systems as well.
