In study phase 1, the response to ethanol will be measured by a quantitative and qualitative approach using Essential Tremor (ET) spiral analysis during a standardized oral ethanol challenge. The clinical response will be correlated to breath-alcohol levels. Participants of study phase 1 will be selected based on their rate of response - dichotomized into a group of responders vs. non-responders - for study phase 2, during an IV ethanol challenge, brain excitability will be tested using transcranial magnetic stimulation (TMS).