Alzheimerâs disease (AD) is a worldwide, incurable disease, and the most common form of dementia. Numbers of cases are rising, and since its discovery the only approved medications have treated only the symptoms, not the pathological cause. With the cost to society rising, the debilitating nature of the disease and the pressure put on the family members and support network of patients, disease modifying therapies are in dire need. Current models have proven an invaluable tool with which to study certain aspects of the disease and the genetics behind it, however the lack of clinically approved medications in the last 20 years suggests new models are needed. Based on the amyloid cascade hypothesis, this thesis initially characterises two models of Î²-Amyloid oligomer (AÎ²o) induced cognitive deficits. Both models are created by ICV injection of soluble AÎ²o into the brain of rat. The models differ only by the molecular weight of the AÎ²o 1-42, one, referred to as low molecular weight (LMW) AÎ²o, with stable dimers, trimers and tetramers, the other, referred to as high molecular weight (HMW) AÎ²o, consisting of assemblies ranging from ~50 to ~150 kDa. It was found that behavioural deficits were similar between the two, with a robust object recognition deficit, but no working memory deficit. Both models also showed a deficit in the synaptic marker PSD-95; however the LMW AÎ²o caused a deficit in the frontal cortex, whereas the HMW AÎ²o caused a hippocampal deficit. The role of the cellular prion protein (PrPC) was explored, by blocking its binding to AÎ²o with the antibody 6D11. Interestingly the two models showed different results. The HMW AÎ²o deficits were completely blocked by the 6D11 application, however the LMW AÎ²o deficits were only partially prevented. Finally, Fasudil, a vasodilator approved in parts of Asia, was used to inhibit Rho-kinase, showing a prevention of the cognitive deficits in the HMW AÎ²o model. The results of this thesis show the ICV administration of AÎ²o to be a useful model for investigating the effects of AÎ²o, provides a platform with which to study the differing effects of AÎ²o with different oligomeric assemblies, and a model to test therapeutic strategies with relevance to AD.