The brain activities associated to the processes of cognition, vision, hearing, smelling, balance, memory and emotion are interdependent. In other words, all activities perform mutual influences on each other, directly and indirectly.
Important aspects to consider in the study of brain activity:
1) The brain response to a stimulus is dependent on the brain pre-stimulus state.
2) Autonomous activities modulate and are modulated by brain activity.
3) Reactions and insights during data collection are essential and must be integrated to the experiment.