It often seems a thin line between love and hate, and now scientists think they know why.

Brain scans of people shown images of individuals they hated revealed a pattern of brain activity that partly occurs in areas also activated¹ by romantic love, Semir Zeki and John Paul Romaya of University College London reported Tuesday.

"This linkage² may account for why love and hate are so closely linked to each other in life," the researchers wrote in the Public Library of Science journal PLoS One.

"Our results show that there is a unique pattern of activity in the brain in the context of hate."

In their study, the researchers showed 17 men and women pictures of someone the volunteers said they hated along with three familiar, neutral faces. The hated individuals were all former lovers or work rivals, except for one famous politician.

The brain scans identified a pattern of activity in different areas of the brain the researchers called a "hate circuit" that switched on when people saw faces they despised, the researchers said.

The so-called hate circuit includes structures in the cortex and the sub-cortex and represented a pattern distinct from emotions such as fear, threat and danger, Zeki said in a telephone interview.

The brain activity also occurred in the putamen and insula, two areas activated when people viewed the face of a loved person. Scientists have linked the regions to aggressive action and distressing³ situations, Zeki said.

But there were important differences as well. A bigger part of the cerebral⁴ cortex - an area linked to judgment⁵ and reasoning - de-activates with love compared to hate.

"It is more likely that in the context of hate the hater may want to exercise judgment in calculating moves to (cause) harm," Zeki said in a statement.

 人们常说：“爱恨只在一线间”，现在科学家找到了其中的原因。

伦敦大学学院的萨米尔•泽克和约翰•保罗•罗马亚于本周二发布研究报告称，他们通过人脑扫描发现，当研究对象看到自己憎恨的人时，大脑进行特定活动的部分区域同时也是“爱情激活区”。

研究人员在《公共科学图书馆-综合》上发表的研究报告中指出：“这一关联或许能解释为什么在现实生活中爱恨总是紧密相连。”

“我们发现人在产生憎恨情绪时，大脑会发生一种特定的活动。”

研究人员向17名男女志愿者展示了他们所憎恨的一些人的照片，其中除一位是政界知名人士外，其他都是研究对象过去的恋人或工作上的死对头。此外，研究对象还看了三张熟人的照片，他们对这几个人既不爱也不恨。

通过对研究对象进行脑部扫描发现，当人们看到自己厌恶的面孔时，大脑中的几个不同区域会发生某种特定的活动，研究人员将这几个由“憎恨”启动的脑区称为“憎恨回路”。

泽克在电话采访中称，大脑“憎恨回路”包括大脑皮层和下皮层中的结构，它所反映的大脑活动形式与恐惧、威胁和危险等情绪截然不同。

“憎恨回路”中的壳核和脑岛两个区域在人们看到喜欢的人时也会活动。泽克说，此前已有科学家发现这两个区域与攻击行为和痛苦体验有关。

但爱与恨毕竟不同，其中最重要的差别是，人在产生爱意时，大部分与判断和推理相关的大脑皮层都处于不活跃状态，而在产生恨意时只有一小部分不活跃。

泽克在声明中说：“这可能是因为人在产生憎恨情绪时，要通过判断来决定如何采取攻击或报复行动。“