 The mechanisms framework has proved particularly fruitful in capturing explanations that appeal to entities at several levels of organization (Darden 2016). An instructive example is Carl Craver’s (2005, 2007) discussion of multilevel and multifield explanation in the context of neuroscientific studies of learning. While the cellular-molecular process of long-term potentiation is critical for memory formation, it is not merely a molecular counterpart of memory. Long-term potentiation is a lower-level component of an overall, multilevel mechanism. Reductionist accounts have neglected the phenomenon of disciplinary integration at the same level of structural organization and invested too heavily in finished reductive explanations, ignoring the dynamic changes in research strategy that precede them (Craver 2005). In addition to searching for molecular correlates of higher-level phenomena (“downward-looking” episodes), there also have been attempts to understand the role of molecular mechanisms in complex higher-level phenomena (“upward-looking” periods of research). Sometimes progress has been achieved independently of or by abandoning reduction as an explanatory goal. This need to change strategies depending on the research context is ubiquitous in mechanistic research (Bechtel 2010), which serves as another reminder for philosophers to attend to actual scientific practice. Even though a mechanism is temporally extended, philosophical analyses of mechanisms may not capture all aspects of temporality (see  Section 4.3).  While discussions have focused on the representation of time relative to a mechanism (e.g., Bechtel 2006, Machamer et al. 2000), not all aspects of the dynamics of biological systems are well represented as mechanisms involving entities and activities. Some might be better modeled using equations (Bechtel 2012, Bechtel and Abrahamsen 2010, 2011, Brigandt 2015, Weber 2008), and in other cases time might be represented independently of the mechanisms being  investigated.[15]