This site contains the widefield imaging datasets from the publication Cortical State Fluctuations during Sensory Decision Making, by Jacobs et al in Current Biology.This data is from the behavioural tasks described in the publication, and is in a compressed SVD format (see Methods in the publication for more details). The companion code is designed to take the data in this format.The datasets provided here contain the top 500 singular values, which is how the data in the publication was analysed, as this was found to sufficiently capture the data. The data contaning up to 2000 singular values can be shared on request.The timestamps of the datasets here are not all aligned with the behavioural datasets; the companion code takes care of this.The data is organised by experimental subject; most subjects were recorded from on multiple days, which form subfolders within the subject folder. Within a day, there may have been several experiments, which again form subfolders within the day folder. The companion code expects this data organisation.The companion code is available at: https://github.com/eakjacobs/Jacobs_et_al_CurrentBiologyFor more information and links to the behavioural and pupil datasets, please follow this link: https://doi.org/10.6084/m9.figshare.13084805The research article can be found (freely available) at https://www.cell.com/current-biology/fulltext/S0960-9822(20)31437-8