Figure 6.

Summary diagram showing the emergence of atypical olfactory behaviors in relation to Aβ deposition levels. Aβ deposition [fibrillar (Thioflavin-S) and fibrillar and/or nonfibrillar (anti-Aβ)] in the OB (all layers) and PCX (both anterior and posterior parts) in relation to olfactory behavioral performance throughout life in Tg2576 mice. Nonfibrillar Aβ levels within the OB were detectable at 3–4 months of age—on the start of impaired odor habituation. Atypical odor discrimination behaviors occur starting at 6–7 months of age. Abnormal odor investigation behavior did not begin until 16 months of age—before OB Aβ escalation. Data (depicted in approximate “levels”) are based on the results displayed in Figures 1–4.