Courtesy of the Research Channel:
"Do the brain's two major memory systems -- implicit and explicit -- have any common features? Implicit and explicit memory both have a short-term componenet lasting minutes (for example, remembering the telephone number you just looked up) and a long-term componenet that lasts days, weeks, or a lifetime (for example, remembering your mother's birthday). Short-term memory is mediated by modifications of existing proteins, leading to temporary changes in the strength of communication between nerve cells. In contrast, long-term memory involves alterations of gene expression, synthesis of new proteins, and growth of new synaptic connections."