English to Russian Science Mathematics & Statistics brain EEG

To determine if a combination of spindle parameters allowed for a better group discrimination, integrated spindle activity was calculated by integrating over time the amplitude of each detected spindle (and by dividing by non-REM sleep duration). We found that integrated spindle activity was markedly reduced in amplitude and number of detections during the first sleep episode in the schizophrenia group in relation to the comparison and depression groups (Figure 3A).

Хочется правильно перевести термин. Нашел текст с описанием того, как вычисляется эта ISA (выше), но почти ничего не помню про интегралы и про то, что может значить "integration over time"...