✅Neural Integration/Infromation Processing Flashcards
What is the simplest form of information processing?
A change in transmembrane potential that determines whether or not action potentials are generated.
What is transmembrane potential?
Charge (voltage) difference between the inside and outside of a cell due to separation in voltage
How are excitatory and inhibitory stimuli integrated?
Interaction between postsynaptic potentials
What are postsynaptic potentials?
Graded potentials that develop in the postsynaptic membrane in response to a neurotransmitter
What are the two types of postsynaptic potentials?
- excitatory postsynaptic potentials (EPSP)
- Inhibitory postsynaptic potentials (IPSP)
What is Excitatory Postsynaptic Potentials?
Graded depolarisation of the postsynaptic membrane
what is the Inhibitory postsynaptic potential?
Graded hyperpolarization of the postsynaptic membrane
What happens in the axon hillock?
The decision whether or not to propagate the action potential along the axon of the post-synaptic neuron
How is the decision whether or not to propagate the action potential along the axon of the post-synaptic neuron achieved?
Through summation of the incoming impulses. If the total impulse reaches threshold, the post-synaptic neuron depolarises and the action potential is propagated
What happens if the sum does not reach the threshold in decision making in the CNS?
The AP is not propagated
What are the two methods of summation?
Temporal and spatial
What is spatial summation?
Integration of simultaneous synaptic currents by a neuron
What is temporal summation?
Summation of synaptic potentials over time
What are the characteristics of temporal summation?
Multiple times
Rapid repeated stimuli at one synapse
On what membrane does temporal summation occur?
A membrane that receives two depolarising stimuli from the same source in rapid succession. The effects of the second stimulus are added to those of the first
What are the characteristics of spatial summation?
Multiple locations
Many stimuli, arrive at multiple synapses
When does spatial summation occur?
When sources of stimulation arrive simultaneously, but at different locations. Local currents spread the depolarising effects, and areas of overlap experience the combined effects
What are neurons constantly under the influence of?
Background synaptic activity
Why can background activity influence neuronal excitability?
Because background activity changes
What does increased excitatory drive results in?
Greater excitability (facilitation)
What does Increased inhibitory drive results in?
Decreased excitability (inhibition)
What are the five stages of the organisation of neuronal pools?
- Divergence
- Convergence
- Serial Procession
- Parallel processing
- Reverberation
What is divergence?
A mechanism for spreading stimulation to multiple neurons or neuronal pools in the CNS
What is convergence?
A mechanism for providing input to a single neuron from multiple sources
What is serial processing?
A mechanism in which neurons or pools work sequentially
What is parallel processing?
A mechanism in which neurons of pools process the same information simultaneously
What is reverberation?
A positive feedback mechanism
What are synapses between the axons called?
Axoaxonic synapses
What do axoaxonic synapses do?
They act to change how effective a synapse is
What is presynaptic inhibition?
Action of an axoaxonic synpase at a synaptic terminal that decreases the neurotransmitter released by presynaptic membrane
What is presynaptic facilitation?
Action of an axoaxonic synpase at a synaptic terminal that increases the neurotransmitter released by presynaptic membrane
What does presynaptic inhibition do?
It inhibits the opening of voltage-regulated calcium channels reducing the amount of neurotransmitter released
What effects might neurotransmitters released at a synapse have?
Excitatory or inhibitory
What does the effect on the axon’s initial segment reflect?
A summation of the stimuli that arrive at any moment
What is The frequency of generation of action potentials an indication of?
The degree of sustained depolarisation at the axon hillock
What do neuromodulators contribute to and what do the act on when released?
Contribute to volume transmission
Act locally on many neurons changing their input/output properties
Each human brain has how many neurones?
100 billion
What do the neurones in each human brain form?
Complex connections and activity patterns that make you who you are
Who do psychoactive drugs affect the brain and personality?
By either increasing or decreasing postsynaptic transmission
What do excitatory drugs do? Give examples
Increase synaptic transmission
Includes many (but not all) stimulant drugs
- Nicotine, cocaine, amphetamine
What do inhibitory drugs do? Give examples
Decrease synaptic transmission
Includes many (but not all) depressant drugs
- Benzodiazepines (valium), alcohol, THC
How do inhibitory drugs ace on synapses?
Mimic inhibitory NTs:
Increase hyperpolarisation of post synaptic neurone
Fewer action potentials
Block Excitatory NTs:
Prevent propagation of action potentials
Block pain pathways by competitive inhibition with pain related NTs
How do excitatory drugs act on synapses?
Block re-uptake pumps for NTs:
NT remains in synapse
Mimic Excitatory NTs:
Increase depolarisation of post-synaptic neurone
More action potentials
Block Inhibitory NTs:
Prevent inhibition of action potentials
