Standardized protocol for plasticity assessment in the aging mouse neocortex using choline-chloride perfusion

Age-related changes in synaptic function are central to the progression of brain pathologies, including neurodegenerative diseases, underscoring the need for experimental approaches that capture neuronal properties across the lifespan. However, obtaining high-quality tissue preparations from aged animals that permit combined structural and functional analyses of individual neurons is challenging due to increased tissue vulnerability. Here, we present a standardized protocol for acute brain slice preparation using transcardial choline-chloride perfusion to reliably obtain intact cortical slices from mice at different ages (young mice: 7-10 weeks old; aged mice: 9-11 months old). Using the medial prefrontal cortex (mPFC) as an example, we show that cortical lamination and subcellular synaptic structure are preserved in supragranular (layer 2/3) pyramidal neurons. Subsequently, we examined spontaneous excitatory synaptic transmission by whole-cell patch-clamp recordings. We demonstrated that forskolin-induced chemical long-term potentiation (cLTP) can be reliably induced and measured in both young and aged slices, revealing age-related differences in the expression of synaptic plasticity. This protocol provides a reproducible framework for investigating synaptic transmission and plasticity in the aging cortex and is broadly applicable to studies of age-related brain disorders.