Neurons can integrate both excitatory and inhibitory signals

Neural Integration

• A neuron receives multiple neurotransmitters, some excitatory and some inhibitory.

• The neuron integrates these signals to determine whether to generate an action potential.

Summation

• A single neuron's neurotransmitter release usually isn't enough to reach the threshold for action potential generation in the postsynaptic neuron.

• Two types of summation can lead to threshold:

  • Temporal summation

  • Spatial summation

Temporal Summation

• Involves one presynaptic neuron firing rapidly.

• The presynaptic neuron releases neurotransmitter repeatedly before the previous release is cleared.

• This rapid, repeated release causes sufficient depolarization in the postsynaptic neuron to reach the threshold.

Spatial Summation

• Involves multiple presynaptic neurons firing simultaneously.

• Several dendrites, each synapsed with a neuron, are activated concurrently.

• The combined effect of ions flowing in from each activated synapse causes enough positive charge to reach the threshold in the postsynaptic neuron.

Conclusion

• Reaching the threshold for action potential generation requires either rapid firing from a single neuron (temporal summation) or simultaneous firing from multiple neurons (spatial summation).

• This is the end of the chapter, study this information for the second lecture test.

• The upcoming test will be more difficult due to the presence of pathways and less review material from previous courses.

• More studying is needed compared to the first test, and even more will be required for the third test.