Abstract: Provided herein are systems and methods for measuring cellular activity within a biological sample comprising living cells over an extended time period. In particular, provided herein are techniques for measuring changes in cellular activity within a tissue sample comprising living cells (e.g., a tissue section comprising living cells) during and/or after exposure to a first stimulus (e.g., a control stimulus) at a first time point and during and/or after exposure to a second stimulus (e.g., a non-control stimulus) (e.g., a pharmaceutical stimulus) at a second time point after the first time point.