Hate On Halloween

It was only a matter of time...and it's just in time for Halloween!

The Neural Correlates of _____________¹ [insert complex emotion or behavior here] is still a news- and flashy-publication-worthy title for your next neuroimaging paper! Use your imagination. How about The Neural Correlates of Procrastination? The Neural Correlates of Blogging? [NOTE: compare and contrast these two for extra credit]. The Neural Correlates of Hematophagy? The Neural Correlates of Sanguivoriphobia? The Neural Correlates of Nasophilia? Add your favorite by commenting on this post.

OK, OK, enough with Sarcasm. On to Hate. Zeki and Romaya (2008) give the following rationale for their study:

...we were interested to explore the neural correlates of hate directed against an individual. ... The hatred may be directed against a public figure or a personally known individual, for a variety of reasons. We made no attempt to distinguish between different types of personal hatred. Instead, we recruited subjects through advertisements, asking them only to volunteer if they experienced an intense enough hate for an individual, without distinguishing further between different categories of individual hate. We conformed as much as possible to our previous studies on romantic and maternal love (Bartels & Zeki 2001, 2004), asking subjects to complete a questionnaire which allowed us to correlate the declared subjective experiences with changes in the BOLD signal.

And the groundbreaking hypothesis? Love and hate might be represented by different brain states! Who knew?

We hypothesized that the pattern of activity generated by viewing the face of a hated person would be quite distinct from that produced by viewing the face of a lover.

Then they really went out on a limb:

In particular, we did not anticipate activation of the brain's reward system but believed that it would result in a different pattern of activity within the emotional brain.

[Oops, more sarcasm there.] However, there might actually be an interesting question addressed by the paper, and it's this:

Given the common association between love and hate, and the relative frequency with which one of these sentiments can transform into the other, we also hypothesized that there would be some strong correlation in the brain sites activated during the experience of these two antipodean sentiments. The results surprised us.

The study participants were 17 people (10 male, 7 female) recruited specifically because they expressed intense hatred for a particular individual. Sixteen people hated an ex-lover or a competitor at work, and one person hated a famous political figure. Two weeks before the experiment, the participants brought in photographs of their hated person and of three other people of the same sex who elicited neutral feelings. Unfortunately, the fake exemplar figure chosen for the paper consisted of four photos that were not all matched for age and race! It makes you wonder whether the authors controlled for that in the actual stimulus materials.


Figure 1. An example set of four processed face images (faces not from this study).

During the experiment, the photographs were presented for 16 sec each, followed by an inter-trial interval of 2 sec. Sometimes a blank screen was presented for 16 sec instead of a face. Each face was presented a total of 8 times.² Subjects were instructed to press a button when the picture disappeared from the screen. After the scanning session (and also during the first visit), ratings of each photographed person were obtained on the Passionate Hate Scale (File S1), designed to be similar to the Passionate Love Scale.

The questionnaire revolved around three elements of hate: (A) negation of intimacy, when an individual seeks a distance from the hated person. This is usually because the hated person arouses feeling of revulsion and disgust, exactly the opposite of the desire for greater intimacy in the context of love; (B) passion, expressing itself in intense anger at, and fear of, the hated person; and (C) devaluation of the hated person through expressions of contempt.

Example questions included (with answers rated on a 7 point scale from "strongly agree" to "strongly disagree"):

A2/ The world would be a better place if X had never existed.
A4/ I would like to interact with X.

B1/ I cannot control my hatred for X.
B3/ I have violent thoughts about X.

C1/ X is scum.

One of the key fMRI results is illustrated below.


Figure 3. Activation for the contrast Hated faces>Neutral faces.

There were 7 regions significantly more active for the Hated Face condition than for the Neutral Face condition. Fig. 3 illustrates the medial frontal gyrus [including the anterior cingulate cortex and the pre-SMA]. Fig. 4 shows the right putamen, bilateral premotor cortex [were they restraining their murderous tendencies?], the frontal pole, and bilateral insula [activated in all sorts of conditions from speech to working memory to reasoning to pain to disgust to the allure of Chanel No. 5]. I won't report on the correlation analysis that related degree of hatred to level of activation across 5,225 voxels because it used an uncorrected statistical threshold of p≤0.01.

And as to The Neural Correlates of Hate, the authors say :

Our studies did indeed reveal a basic pattern. As far as we can determine, it is unique to the sentiment of hate even though individual sites within it have been shown to be active in other conditions that are related to hate. The network has components that have been considered to be important in (a) generating aggressive behavior and (b) translating this behavior into motor action through motor planning. Finally, and most intriguingly, the network involves regions of the putamen and the insula that are almost identical to the ones activated by passionate, romantic, love.

Popular media outlets, of course, really love this sort of thing, especially when your university issues this type of press release:

Brain’s ‘hate circuit’ identified

28 October 2008

People who view pictures of someone they hate display activity in distinct areas of the brain that, together, may be thought of as a ‘hate circuit’, according to new research by scientists at UCL.

See the newest neurocurmudgeon (The Neuroskeptic) for more skepticism. Zeki's flowery prose doesn't help matters:

“Hate is often considered to be an evil passion that should, in a better world, be tamed, controlled, and eradicated. Yet to the biologist, hate is a passion that is of equal interest to love. Like love, it is often seemingly irrational and can lead individuals to heroic and evil deeds. How can two opposite sentiments lead to the same behaviour?”

I must have missed the evil and heroic portion of the experiment...


Footnotes

¹ Top hits include The Neural Correlates of Consciousness, Desire (Kawabata & Zeki), Maternal and Romantic Love (Bartels & Zeki), Reward-Related Trial-and-Error Learning, Sensory Awareness, Subjective Value During Intertemporal Choice, Motor Skill Automaticity, and [my personal favorite] David Chalmers (NC/DC, the foremost Black Metal/Christian Rap band, is not to be confused with David Chalmers the philosopher).

² Not exactly an extraordinary S/N. And who knows what the subjects were actually thinking about for 16 sec?

References

Bartels A, Zeki S. (2000). The neural basis of romantic love. Neuroreport 11:3829-34.

Bartels A, Zeki S. (2004). The neural correlates of maternal and romantic love. Neuroimage 21:1155-66.

Semir Zeki, John Paul Romaya, Jan Lauwereyns (2008). Neural Correlates of Hate. PLoS ONE, 3 (10). DOI: 10.1371/journal.pone.0003556

In this work, we address an important but unexplored topic, namely the neural correlates of hate. In a block-design fMRI study, we scanned 17 normal human subjects while they viewed the face of a person they hated and also faces of acquaintances for whom they had neutral feelings. A hate score was obtained for the object of hate for each subject and this was used as a covariate in a between-subject random effects analysis. Viewing a hated face resulted in increased activity in the medial frontal gyrus, right putamen, bilaterally in premotor cortex, in the frontal pole and bilaterally in the medial insula. We also found three areas where activation correlated linearly with the declared level of hatred, the right insula, right premotor cortex and the right fronto-medial gyrus. One area of deactivation was found in the right superior frontal gyrus. The study thus shows that there is a unique pattern of activity in the brain in the context of hate. Though distinct from the pattern of activity that correlates with romantic love, this pattern nevertheless shares two areas with the latter, namely the putamen and the insula.

No-one loves you and you know it
Don't pretend that you enjoy
Or you don't care
'Cause now I wouldn't lie
Or tell you all the things you want to hear
'Cause I hate you
'Cause I hate you
'Cause I hate you
'Cause I hate you

-Green Day, Platypus (I Hate You)

Viva Hate!