Figure 1

Impaired spatial cognition and reduced brain activity in APPxPS1-Ki mice. (A) The general protocol of the object recognition task is schematized on the left. Mice were first trained with a configuration of three identical objects (ACQUISITION phase) and then retested after a spatial change occurred in the arena (RETENTION phase). Good memory performance is assessed by a detection of the spatial change (i.e., increased exploration of the displaced object). The right part of the figure illustrates the good memory score of PS1-Ki mice that performed well above chance level (dotted line) while APPxPS1-Ki mice were significantly impaired. *p < 0.05. ^###p < 0.001 (different from chance level). (B) Representative microphotographs of fos immunoreactivity in PS1-Ki and APPxPS1-Ki mice after behavioral stimulation. Note the decrease in the number of fos-positive nuclei in the isocortex and hippocampal subfields of APPxPS1-Ki mice. DG: dentate gyrus. Scale bar: 500 µm. (C) Quantification of fos immunostaining in three different regions of interest. For all regions, APPxPS1-Ki mice displayed decreased immunoreactivity levels. *p < 0.05; **p < 0.01.