Fig. 1: Mice provided with an exercise wheel are more active.

a Experimental timeline, showing experimental groups (APOE genotype, and wheel access), time of cranial window implantation and data collection. b Schematic of the in vivo recording set up (D. Grijseels, CC-BY¹²). The mouse was head fixed to two metal arms and was freely walking on a rotating cylinder containing a rotary encoder while facing two screens that presented a visual stimulation (drifting grating). Recordings of net haemodynamic measures were obtained with an Oxy-CBF probe and measurements of neurovascular function were recorded with two-photon microscopy. c Activity levels were recorded from the home cage of the mouse using a USB infrared camera mounted in a 3D printed support positioned on the top of the cage. The camera was connected to a PC where videos are recorded using Bonsai.rx. The schematic was created using images of a monitor⁸³, mouse⁸⁴ and cage⁸⁵, available with Creative Commons licences. d Videos were analysed using DeepLabCut. A deep learning network was trained to recognize mouse body parts (coloured dots on cranial window, right head plate, left head plate and tail) and a dark marker placed on the wheel (wheel marker- yellow dots indicate inner mark and outer mark). e Mouse position in each frame from one representative recording, tracked using DeepLabCut, allowing calculation of the distance travelled by the mouse (from mouse displacement plus movement of wheel marker). f Mouse weights increased across the experiment but were not affected by genotype or exercise group. N = 3 mice per group. Mean distance run per hour for each experimental group at (g) the onset of wheel exposure and (h) after 4 months of wheel access. i Distance run every 24 h for each mouse at the start and after 4 months of wheel access. Dots are daily distances travelled by each mouse during each day of the recording session. Bars and error bars: mean +/- SEM. Daily distances: N = 14–26 from N = 3–6 mice. For details on N and statistical outputs see Supplementary Table 1 in Supplementary Data.