Synapse Weights, Memory and Learning

Quora: How do changes at the synapse level affect our memory processing?

We learn our memories. Learning is evidenced by changes in the magnitude of the signal that is transported across the synaptic gap.

Figure 1. Neural Input-Output with Synapses before dendrites into neuron, summed, if threshold exceeded signal is fired, which at all receiving
Figure 1. Neural Input-Output with Synapses

In Figure 1 the basic units of a single neuron’s information processing are displayed.

Starting on the left, the small circles represent synapses.

Each of the roughly ten thousand inputs cross the synaptic gap modified by the strength (or weighting) of the individual synapse.

The ten thousand inputs are basically broken into two types—excitatory and inhibitory signals. As the terms suggest, excitatory inputs contribute to the electrical potential while inhibitory ones decrease the electrical potential.

The combined electrical potential is summed within the neuron.

If the net magnitude exceeds the neural threshold, a full signal is sent down the axon and out to receiving neurons.

If the net magnitude does not exceed the neural threshold, nothing happens. That is, no signal is sent down the axon.

At each neuron connected to the axon , the axon signal reaches a synapse, where the existing weighting adjusts the magnitude of the signal that neuron receives.

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