Repetitive transcranial magnetic stimulation (rTMS) alters neuroplasticity and can treat various neurological disorders. However there is uncertainty about the mechanisms of action and how differing the parameters of rTMS affects the outcome. To address these questions this thesis explored altering the location, intensity and frequency of rTMS in preclinical models of depression and Alzheimer's disease, examining behavioural and biological outcomes. For depression, higher intensity rTMS to frontal cortex alleviated depressive-like behaviours Whereas, for Alzheimer's disease, excitatory low intensity rTMS the to hippocampus improved memory. These tailored parameters were shown to relate to the underlying neuropathologies of the each disorder.