对恋爱中人们大脑的扫描，也有助于使科学对各种形式爱情的领会变得更为精确。Rutgers 大学的一位研究人员Helen Fisher，同时是一本关于爱情的新书作者，她提出，爱会以三种滋味出现：欲望，浪漫的恋爱和长期的附属关系。三种滋味的爱情虽有一些重叠，但本质上是截然不同的现象，并且具有各自的情绪和激发系统，以及相伴的体内化学物质。这些系统通过进化后以分别让交配，伴侣联接和养育子女成为可能。

Lust, of course, involves a craving for sex. Jim Pfaus, a psychologist at Concordia University, in Montreal, says the aftermath of lustful sex is similar to the state induced by taking opiates. A heady mix of chemical changes occurs, including increases in the levels of serotonin, oxytocin, vasopressin and endogenous opioids (the body's natural equivalent of heroin). “This may serve many functions, to relax the body, induce pleasure and satiety, and perhaps induce bonding to the very features that one has just experienced all this with”, says Dr Pfaus.

首先当然是欲望，包括对性的强烈渴求。蒙特利尔Concordia大学的一位心理学家，Jim Pfaus说道，贪欲的性行为其结果和使用鸦片引起的状况颇相类似：一种令人兴奋的混合化学变化，包括血液复合胺(5羟色氨)，催产素，抗利尿激素和内非肽(身体内的海洛英的天然同等物) 的水平升高。“这可能提供许多功能，如放松身体，产生快乐和满足感, 也可能导致把某些特征与刚才的全部经历联结起来，”Pfaus博士补充道。

Then there is attraction, or the state of being in love (what is sometimes known as romantic or obsessive love). This is a refinement of mere lust that allows people to home in on a particular mate. This state is characterised by feelings of exhilaration, and intrusive, obsessive thoughts about the object of one's affection. Some researchers suggest this mental state might share neurochemical characteristics with the manic phase of manic depression. Dr Fisher's work, however, suggests that the actual behavioural patterns of those in love—such as attempting to evoke reciprocal responses in one's loved one—resemble obsessive compulsive disorder (OCD).

接下来便是两性吸引，双方处于相爱的状态 (就是我们所知的浪漫的、或强迫性的恋爱)。这是纯粹的欲望的升华，它使人们总能回到某个特定配偶身边。这种状态的特征，是兴奋感和对情感对象打扰式的和强迫性的思恋。一些研究员提到，这一心理状态可能和狂躁状态的躁郁症有相同的神经化学特征。Fisher博士的工作揭示了恋爱人群真实的行为模式，比如：试图唤起被爱者的报答——类似于强迫性混乱症(OCD)。

爱情的科学

That raises the question of whether it is possible to “treat” this romantic state clinically, as can be done with OCD. The parents of any love-besotted teenager might want to know the answer to that. Dr Fisher suggests it might, indeed, be possible to inhibit feelings of romantic love, but only at its early stages. OCD is characterised by low levels of a chemical called serotonin. Drugs such as Prozac work by keeping serotonin hanging around in the brain for longer than normal, so they might stave off romantic feelings. (This also means that people taking anti-depressants may be jeopardising their ability to fall in love.) But once romantic love begins in earnest, it is one of the strongest drives on Earth. Dr Fisher says it seems to be more powerful than hunger. A little serotonin would be unlikely to stifle it. ()