Neural networks Flashcards
What are the stages of Neural Darwinism?
Developmental Selection
Experiential Selection
Mapping
What kind of control is the developmental selection stage under?
Genetic control
What kind of control is experiential selection under?
Experiential control
What is mapping?
The idea that numerous neural maps are formed by the brain
Ex. Pressure maps for each area of the body
What does LTP require (in regards to neuronal firing)
Simultaneous presynaptic and post synaptic neuronal firing
Does LTP rely on protein kinases or phosphatases?
Relies on protein kinases
Does LTD depend on protein kinases or phosphatases?
Relies on protein phosphatases
What does LTD require (neuronal firing)
Asynchronous firing of pre and post synaptic neurons
What determines whether an LTD or LTP is formed?
The AMOUNT of calcium ions allowed into the post synaptic neuron
(BOTH require the NMDA receptor activation and entry of calcium into post synaptic cell)
What is a serious downside to serial processing?
It is vulnerable to damage which could block further fxn
Why is distributed processing a safer route in neural networks?
It is more resilient to damage.
Multiple interconnections allow for continued communication and function
What is a serial processing scheme?
Neurons within an assembly connect with one other neuron
What is a distributed processing scheme?
Neurons within an assembly contain multiple connections
What is a feedforward excitatory connection?
Info from a lower level of a circuit being transmitted by a presynaptic neuron to a post synaptic neuron at a higher level
What is a feedback excitatory connection?
Info is transmitted from a presynaptic lower level neuron to a postsynaptic higher level neuron. Output from postsynaptic neuron excites the presynaptic input neuron
Lateral excitatory connection
Presynaptic neuron excites postsynaptic neurons within the same processing level
What is feedforward inhibitory connection?
Presynaptic neuron excites an inhibitory inter neuron which goes on to inhibit a tertiary neuron
What is a feedback inhibitory connection?
Output of a higher order level of a circuit inhibits activity of that circuit.
A presynaptic neuron excites a postsynaptic neuron and that neuron goes on to excite an inhibitory inter neuron that inhibits the initial presynaptic neuron
What is a lateral inhibitory connection?
Presynaptic neuron excites inhibitory inter neurons which inhibit postsynaptic neurons at the SAME processing level
What is disinhibition?
Inhibitory inter neurons can sometimes be used indirectly to cause net excitation within a circuit
If inhibitory input is greater than excitatory input, the neuron will be silent.
If inhibitory input is inhibited, the excitatory input would cause the neuron to fire
What is divergent process streaming?
A neuron projects input to a large number of target neurons via axon collaterals
Can also refer to one neuron activating more than one receptor subtype
What is convergence process streaming?
A neuron receives input from a large number of other neurons
Can also apply to the ability of different NTs to converge to affect same circuit or network
What is a hierarchical circuit?
Each level is regulated by local circuits and all 3 types of processing occur within the circuits
What is parallel processing?
Info flows in a side-by-side manner in a hierarchical circuit
What is reciprocal processing?
Info flows back and forth in a hierarchical circuit
What is a local circuit?
Found within hierarchical circuits and alter the processing at each hierarchical level
Determine info passed down to next stage
Include feedforward, feedback connections, excitatory and inhibitory connections
Which cells of the CNS retain the ability to divide?
Microglial cells
What are the components of the neural triad?
Neurons
Neuroglial cells
Cerebral vasculature
Which neuroglial cells make up the BBB?
Astrocytes
What is Neural Darwinism?
The idea that the brain is a somatic selection, just like evolution, but done in a much shorter time course
