This theoretical review clarifies the concept of "language attrition " by defining the phenomenological and contextual features of its utilization, discussing the definition of contradictions, and suggesting potential directions for future research. Taking into account existing data, we regard the existing approaches to language attrition and analyze the mechanisms underlying the phenomenon. This analysis seems to be the first step in building up an integral theoretical model summarizing the available empirical data. It helps to apply a neurobiological approach, allowing to identify neural markers of language attrition at different levels of language processing and within different language categories. To this end, we propose specific experimental approaches to recording neural traces of attrition and formulate working hypotheses based on proposed experimental paradigms.