FIGURE 3.

Species distribution and sample size. (A) Animal representation in the documented studies. (B) Animal species occurrence in the literature over time. Rats and non-human primate (NHP) represent the major species used, however, since 2008, mice have been used in a growing proportion of animal fMRI studies. (C) Number of animals used per fMRI study irrespective of number of groups or classes. NHP studies are carried out with fewer animals (Percentiles_{25, 50, 75} = [2, 3, 5]), whereas studies involving mice involved larger number of animals (Percentiles_{25, 50, 75} = [17, 24, 34]).