Aging is associated with decline in cognitive function, but the underlying mechanisms have not been elucidated. Normal activity of pyramidal cells and parvalbumin-expressing interneurons (PV neurons) is essential for cognitive function. PV neurons participate in the regulation of pyramidal-cell firing. Abnormal function of PV neurons may occur with aging. We analyzed the density and the percentage of PV neurons surrounded by perineuronal nets (PNNs) in the entire cortex of adult (3-month-old) and aged (24-month-old) mice. PNNs are extracellular matrix molecules that cover PV neurons and control synaptic plasticity. PV-neuron density decreased in some cortical areas of aged compared to adult mice. In particular, in the retrosplenial granular cortex (RSG) of aged mice, pyramidal cells expressed PV protein at high levels. This study suggests that the RSG of aged mice is in an abnormal activated state. RSG function abnormality may be part of the cognitive decline mechanism.

衰老与认知功能下降有关，但尚未阐明其潜在机制。锥体细胞和表达小白蛋白的中间神经元（PV神经元）的正常活动对于认知​​功能至关重要。PV神经元参与锥体细胞放电的调节。随着年龄的增长，PV神经元的功能可能会发生异常。我们分析了成年（3个月大）和老年（24个月大）小鼠整个皮质中被神经周围神经网络（PNN）包围的PV神经元的密度和百分比。PNN是覆盖PV神经元并控制突触可塑性的细胞外基质分子。与成年小鼠相比，某些年龄的皮质区域的PV神经元密度降低。特别是，在老年小鼠的脾后颗粒皮质（RSG）中，锥体细胞高水平表达PV蛋白。这项研究表明，老年小鼠的RSG处于异常激活状态。RSG功能异常可能是认知下降机制的一部分。