Final answer:
Neural activity is governed by the balance and sum of excitatory and inhibitory signals, as well as by the frequency of neuron firing. Summation, both spatial and temporal, and high firing frequencies can lead to stronger responses or sustained contractions known as tetanus.
Step-by-step explanation:
In the nervous system, the overall neural activity is influenced by the interactions between excitatory and inhibitory nerve fibers and the mechanisms of summation and firing frequency. Summation can occur in two forms: spatial summation and temporal summation. Spatial summation involves multiple signals from different presynaptic neurons accumulating at the same time at various locations on the dendrites or soma of the postsynaptic neuron. Temporal summation refers to multiple signals from a single presynaptic neuron occurring in rapid succession at the same site to influence the postsynaptic neuron.
The frequency of action potentials, or firing frequency, affects cell response. A higher frequency of impulses can lead to wave summation, where the muscle or neuron does not fully relax between stimuli, leading to a stronger contraction or response. When the frequency is high enough, relaxation phases disappear, and tetanus, a sustained contraction, can occur in muscles.