Cognitive behavioral assessments 7 months after PBS and α-syn PFF gastrointestinal injection in WT (n=9–10), vagotomy (TV) (n=7–8) and Snca−/− mice (n=10). (A) Escape latency time and (B) probe trial session in the Morris water maze test. (C) Representative swimming paths of mice from each group in the MWMT on the probe trial day 5. The mice were then given two trial sessions each day for four consecutive days, with an inter-trial interval of 15 min, and the escape latencies were recorded. This parameter was averaged for each session of trials and for each mouse. (D) Exploration time of the objects and (E) percentage of novel object recognition index in the novel object recognition test. (F) Effect of TV and α-syn deficiency on α-syn PFF-induced hippocampal-dependent contextual or amygdala-dependent fear conditioning learning and memory in the step-through passive avoidance test. The time taken for a mouse to enter the dark compartment after door opening was defined as latency for both training and test trials. (G-H) Effect of TV and α-syn deficiency on α-syn PFF-induced short-term or working memory in the Y-maze test. (G) Percentage of alternative behavior and (H) number of arm entries in the Y-maze test. Error bars represent the mean ± S.E.M. All behavior tests were analyzed by two-way ANOVA followed by post-hoc Bonferroni test for multiple group comparison. ##P < 0.01, ###P < 0.001 vs. PBS gastrointestinal injected WT group. *P< 0.05, **P < 0.01, ***P < 0.001 vs. α-syn PFF gastrointestinal injected WT group. n.s: not significant. See also Figure S6 and Movies S2.