Expanding the number of words you know excites the same parts of your brain as do sex and drugs. Scientists from Spain and Germany found that the the part of the brain called the ventral striatum
is activated during a wide range of pleasurable activities, such as eating great food, having sex and taking drugs. During word learning activities, synchronization between the cortical language regions and the ventral striatum was also increased. Furthermore, those with better connections between these two circuits were found to be able to learn more words than those with weaker links.
This might be useful for couples using NFP.