Paul - Encoding Information in the Nervous System Flashcards
Explain the concept of neural encoding and provide
examples of how nervous systems encode information in action potentials.
Definition: Neural encoding is the process by which neurons convert external stimuli into electrical signals (action potentials or spikes) and make synapses that can be transmitted and processed by the brain. This can be done with smell: Odours are encoded by action potential rates across a population of neurons
Explain how resting membrane potentials are generated.
Resting membrane potentials are in a equilibrium state - electrical forces balance chemical forces.
Resting potential: ~-70 mV (intracellular relative to extracellular)
There is more K+ inside the cell than outside and more NA+ outside the cell than inside.
Resting membrane potential: net ion current is zero
Explain how action potentials are generated.
Depolarisation - happens by Na+ channels opening first and Na+ rushing into the cell
The rising phase - when reaching the threshold the membrane potential becomes more positive and more Na+ channels open, this loop continues happening because it is a self sustaining process.
Falling phase of action potential - the voltage-gated Na+ channels become inactivated and Voltage-gated K+ channels open, and K+ flows out of the cell.
Undershoot (Hyperpolarization) -Voltage-gates K+ channels are still open (in addition to the permanently open K+ channels) so there is more K+ flowing out then when at rest
What are dendrites?
They are a major site of synaptic input from other neurons. (Tentacle looking things coming from the cell body)
What is the neuronal cell body a major site of?
Integration of synaptic potentials
What is the axon?
The axon is the conduction component of the neutron, propagating action potentials to the axon terminals. (long skinny bit)
What happens at the presynaptic terminals?
At the presynaptic terminals the output of the neuron (secretion of neurotransmitter) can alter the activities of other cells.
Draw and label the diagram of a neuron
Look at Lecture 4 for the answer.
