Which symptom is primarily associated with fever in relation to seizure activity?

The symptom primarily associated with fever in relation to seizure activity is a decreased seizure threshold. When a person experiences a fever, particularly in young children, their brain becomes more excitable and sensitive to stimuli. This heightened excitability can lower the threshold at which seizures may occur, making it easier for seizures to be triggered during febrile episodes.

Increased seizure frequency could also be observed in the context of fever, but it's more accurately attributed to the decreased seizure threshold, as the underlying excitability is what facilitates the occurrence of seizures during febrile illness. Similarly, the duration of seizures may not be directly influenced by fever itself, as fever tends to increase the likelihood of seizure occurrence rather than affecting how long they last. Hence, decreased seizure threshold is the most specific and relevant association regarding fever and seizure activity.