  Emotion recognition technology through analyzing the EEG signal is currently
an essential concept in Artificial Intelligence and holds great potential in
emotional health care, human-computer interaction, multimedia content
recommendation, etc. Though there have been several works devoted to reviewing
EEG-based emotion recognition, the content of these reviews needs to be
updated. In addition, those works are either fragmented in content or only
focus on specific techniques adopted in this area but neglect the holistic
perspective of the entire technical routes. Hence, in this paper, we review
from the perspective of researchers who try to take the first step on this
topic. We review the recent representative works in the EEG-based emotion
recognition research and provide a tutorial to guide the researchers to start
from the beginning. The scientific basis of EEG-based emotion recognition in
the psychological and physiological levels is introduced. Further, we
categorize these reviewed works into different technical routes and illustrate
the theoretical basis and the research motivation, which will help the readers
better understand why those techniques are studied and employed. At last,
existing challenges and future investigations are also discussed in this paper,
which guides the researchers to decide potential future research directions.
