Central dopamine pathways mediate partner preference behavior, while vasopressin in the ventral pallidum and oxytocin in the nucleus accumbens and paraventricular hypothalamic nucleus mediate partner preference and attachment behaviors.[8][11] Sex drive is modulated primarily by activity in the mesolimbic dopamine pathway (ventral tegmental area and nucleus accumbens).[8]Trace amines (e.g., phenethylamine and tyramine) play a critical role in regulating dopaminergic activity in the central nervous system, and consequently in these pathways.[12]Testosterone and estrogen contribute to these drives by modulating activity within dopamine pathways.[8] Adequate brain levels of testosterone seem important for both human male and female sexual behavior.[13]Norepinephrine and serotonin have a less significant, contributing role through their neuromodulatory effects upon dopamine and oxytocin release in certain pathways.[8]The chemicals triggered that are responsible for passionate love and long-term attachment love seem to be more particular to the activities in which both persons participate rather than to the nature of the specific people involved.[9] Individuals who have recently fallen in love show higher levels of cortisol.[14]
