If there are many repetitions of the impulse traveling along the neural pathway (through rehearsal and practice), then many larger spines are formed so that there are anatomical changes at the synapses and the memory trace persists.

When there are repettions of the impulse traveling along the neural pathway, and the memory trace persists is called long therm memory.

Explanation:

Long therm memory: lasts for a long period of time, and it involves the creation of new synaptc connections. This type of memory requires repetitions of the stablishing synapsis among neurons.

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