Altered corticostriatal synchronization associated with compulsive-like behavior in APP/PS1 mice.

Mild behavioral impairment (MBI), which can include compulsive behavior, is an early sign of Alzheimer's disease (AD), but its underlying neural mechanisms remain unclear. Here, we show that 3-5-month-old APP/PS1 mice display obsessive-compulsive disorder (OCD)-like behavior. The number of parvalbumin-positive (PV) interneurons and level of high gamma (γhigh) oscillation are significantly decreased in the striatum of AD mice. This is accompanied by enhanced β-γhigh coupling and firing rates of putative striatal projection neurons (SPNs), indicating decorrelation between PV interneurons and SPNs. Local field potentials (LFPs) simultaneously recorded in prefrontal cortex (PFC) and striatum (Str) demonstrate a decrease in γhigh-band coherent activity and spike-field coherence in corticostriatal circuits of APP/PS1 mice. Furthermore, levels of GABAB receptor (GABABR), but not GABAA receptor (GABAAR), and glutamatergic receptors, were markedly reduced, in line with presymptomatic AD-related behavioral changes. These findings suggest that MBI occurs as early as 3-5 months in APP/PS1 mice and that altered corticostriatal synchronization may play a role in mediating the behavioral phenotypes observed.