The memory for time and space differentially engages the proximal and distal parts of the hippocampal subfields CA1 and CA3
Fig 2
Memory task and location of the imaging frames.
(A) Behavioral protocol. The animals were placed into an open field with 4 identical objects during the 10-min study phase 1, followed by a 50-min delay phase. After the first delay phase, animals returned to the same open field with a new set of 4 identical objects during the 10-min study phase 2. Following the second 50-min delay phase, memory for the spatial arrangement of the objects (where the objects were originally placed) and the temporal aspect of the task (when the objects were presented) was assessed by returning animals to the open field for a third time, with 2 copies of the objects from study phase 2 (recent stationary objects) and 2 copies of the objects from study phase 1 (“old” objects: one stationary and one displaced), and by measuring the time mice explored each object that was used to calculate discrimination ratios during the test phase. (B) Location of the imaging frames [49]. Black frames define the level at which images were taken with a 40× objective. Three images were taken per target area on nonconsecutive sections that covered approximately 400 microns. Counting was performed only on neurons as described in [43] and totaled approximately 270 neurons per area.