
Application to biomedical signals 151
two scenarios leading to decrease of power measured on the EEG level. First, the
simplest, is that in the whole patch of cortex the oscillations in a given frequency
band disappeared; perhaps the frequency of oscillation had shifted to some other
frequency band. The second scenario is that, during the baseline time, an ensemble
of neural populations oscillates synchronously in a given rhythm. Then during the
information processing or mental activity the ensemble splits into many smaller en-
sembles, each oscillating with its own frequency and phase. In the superposition of
their activity we would observe a decrease ...