Older mice showed less stable neural maps of space and fewer neurons marked by the gene Bglap3 in a navigation-related brain region. Temporarily quieting this subgroup in young mice also disturbed spatial coding. The experiments connect a particular cell population with the circuit’s function while leaving the full explanation of age-related changes unresolved.
A mouse experiment examined the medial entorhinal cortex, a brain region that helps represent location and direction. Researchers monitored 8 young and 10 old animals as they moved freely. The younger group was 3–4 months old; the older mice were over 28 months. In the older group, grid cells, which respond in patterns associated with location, were less common and their spatial activity was less stable.[1]
The animals’ running speeds and coverage of the enclosure were similar across age groups. Tissue analysis then compared gene activity while retaining information about where cells were located. Samples from 2 young and 2 old mice revealed 1664 genes with differing activity. Bglap3 marked an excitatory neuron subgroup in the cortex’s third layer, and further tissue observations supported a decline in these cells with age.[1]
Temporarily suppressing the Bglap3-marked neurons in young mice disturbed location, direction and boundary-related responses elsewhere in the network. The intervention supports a contribution from this subgroup to spatial coding. Its connections may influence other cells directly or through intermediate pathways; that relationship remains unresolved. The results concern mice and leave open the extent of this cell loss’s contribution to the broader aging pattern.[1]
