Michael Higley

This protocol describes the method for injection of α-Synuclin PFF and monomer into the mouse brain. The second part of the protocol describes preparation of acute slices from these mice and whole-cell patch clamp recordings.

α-Synuclein aggregation is a hallmark of Parkinson’s disease and dementia with Lewy bodies, where cortical pathology is closely linked to cognitive decline. Although synaptic dysfunction is a recognized feature of α-synucleinopathy, the selective vulnerability and spatial progression of specific cortical synapse subtypes remain unclear. Using high-resolution imaging and electron microscopy in a mouse model, we show synaptic enrichment of α-synuclein aggregates, with progressive pathology associated with loss and ultrastructural alterations of intracortical VGLUT1+ excitatory synapses, while long-range VGLUT2+ synapses remain largely preserved. Inhibitory VGAT+ synapses exhibit modest late-stage postsynaptic disruption. Electrophysiological recordings confirm impaired excitatory transmission. Transcriptomic profiling reveals altered synapse-related pathways and candidate resilience mechanisms in affected neurons. These findings highlight synapse-type-specific vulnerabilities and establish VGLUT1+  intracortical excitatory synapses as critical sites of disrupted cortical connectivity in α-synucleinopathy.