(A) In the past 20 years, neuroscience research has shifted from area-wide manipulations, such as lesions or pharmacological silencing, to circuit-level manipulations that enable researchers to target defined subsets of neurons.(B) For many decades, researchers used electrodes to monitor the extracellular activity of single neurons. The activity pattern of each neuron was often characterised by tuning curves or receptive fields. Newly developed tools can record thousands of neurons simultaneously, enabling the study of population-level dynamics using advanced computational methods.(C) Traditional laboratory experiments in artificial settings (eg, a water maze or lever-pressing tasks) often restrict animals to unnatural behaviours or stereotyped movements. Neuroscientists have moved towards studying natural behaviours (eg, prey avoidance or nesting) in more complex, realistic settings. Grid cell data and images in part B were provided by Valentin A Normand from our laboratory.