Inside the Brain, Behind the Music is part of an ongoing series of dispatches written for the The Beautiful Brain by neuroscientist and rock musician Joseph LeDoux. Each piece presents the personal and scientific background of a song from his band The Amygdaloids‘ latest brain-themed album, Theory of My Mind (Amazon, iTunes, Amygdaloids.com).
Part 5: “Crime of Passion”
The amygdala is an evolutionarily ancient almond-shaped structure in the brain.
This week’s song is “Crime of Passion.” When I was writing this, I felt I was channeling Johnny Cash. It just seemed like the kind of song he might have done. Through a simple twist of fate, the amazing Rosanne Cash ended up singing this song with me on the record.
So why did I write a song called “Crime of Passion”? If you’ve been reading these Dispatches, you know that I am very interested in how brains respond automatically (unconsciously) in certain emotionally provoking situations. Over the years, this rep has gotten around, and I’ve been contacted from time to time by people seeking help in legal cases involving murder, in particular prisoners on death row looking for a angle that might give them the basis of new hearing. The hope is that I might provide information that would buttress the argument for shifting the blame from the defendant to his brain, especially his amygdala. This strategy is apparently not unusual. Consider the following quote from a 2007 article in The Sunday Times of London. The author, Raymond Tallis, is describing the basis for an “amygdala defense”: “The case against Mr X must be dismissed. He cannot be held responsible for smashing Mr Y’s face into a pulp. He is not guilty, it was his brain that did it. Blame not Mr X, but his overactive amygdala.”
The idea of an amygdala defense is fairly new in detail but not spirit. In 1843, Daniel M’Naghten shot the British Prime Minister and pleaded temporary insanity. The insanity defense in a number of countries, including the US, is based on the M’Naghten case. Temporary insanity caused by strong emotional arousal, usually from catching one’s spouse in a compromising position, is often accepted as a rationale for leniency. The amygdala defense simply replaces the psychological justification (temporary insanity) with a brain explanation (an overactive amygdala).
Scientifically, we can weave together the various pieces of the puzzle into a coherent story that might justify a temporary insanity/crime of passion/amygdala defense. Through rational thought, we control our behavior. Rational thought is a function of the mind and a product of cortical areas of the brain. The amygdala, which works unconsciously, is a brain region responsible for strong emotional responses. Strong emotion (stress) due to an overactive amygdala disrupts the function of cortical areas involved in rational thought, in part by releasing hormones and other chemicals that impair cortical function. Unconscious processes controlled by the amygdala can interfere with rational thought and allow the performance of irrational behaviors that the person would not otherwise not commit.
The author of the Sunday Times piece was none too pleased with this movement towards the “my brain made me do it” defense. Where do you draw the line with this kind of defense? When is the brain responsible and when are you responsible? How do you ever know? Why wouldn’t everyone make this case? Tallis goes on to quote Stephen Morse, a law professor, who argues: “it is people, not brains, who commit crimes and neuroscience . . . can never identify the mysterious point at which people should be excused responsibility for their actions.”
Tallis sees one instance where “the neuromitigation of blame” might be acceptable: in instances where there is unambiguous evidence of grossly abnormal brain function or abnormal mental function due to clear cut illness that may have its origin in brain disease. This reminds me of the “Texas Tower Sniper,” Charles Whitman, who gunned down University of Texas students. He too was gunned down, and an autopsy revealed a tumor impinging on his amygdala. This medical condition was given at least some of the blame. Had he survived and gone to trial, and had modern brain imaging techniques been available, and had they been used and locate the tumor, Whitman might well gotten something short of a death sentence, even in Texas.
But let’s go back to the amygdala defense in the crimes of passion sense (as opposed to the damaged brain sense). There are two versions of this that need to be distinguished. The first is the “my amygdala did it.” This is the version I have most often been contacted about. In this version, the amygdala, when activated, is responsible for the act of murder. When the cuckold catches his wife, he picks up a knife or baseball bat, walks over to the bed, and kills his wife, her lover, or both. But as far as we know, actions like these are not what the amygdala does. It is hard-wired to control simple, preprogrammed responses like freezing, not complex sequences of behaviors, like finding a weapon and using it. Other regions like the basal ganglia might be able to do this, and they probably also function unconsciously. But I’ll leave it to a basal ganglia expert so say whether the caudate nucleus or the nucleus accumbens can commit a crime of passion.
The other version of the amygdala defense is more reasonable scientifically. This is the overactive amygdala hypothesis that Mr. Tallis mentioned. In this version, intense emotional arousal strongly activates the amygdala and this biases the way brain areas (including action control regions such as those in the basal ganglia) subsequently behave (or misbehave). Can this happen? Sure. Did it happen in a particular case? Who knows? But even if we could prove through imaging that the amygdala was hyperactive to emotional stimuli in the perp close in time to the crime, where would we draw the line between active and hyperactive, and most important, could we link amygdala activity in a causal way to the crime?
Personally, I don’t think that imaging can tell us much about the amydala’s role in a crime. The amygdala participates in a lot of functions, most famously, fear and aggression. But it is also involved in evaluating food as tasty and safe or poisonous, and in processing the meaning of odors; it contributes to reproductive behavior (sexual and parenting behavior); it is also important in the reinforcement or reward of behavior. A hyperactive amygdala, in other words, does not mean anything on its own. Very specific tests need to be performed to determine why it is hyperactive (which function or functions it is hyperactive in relation to). Perhaps most important, imaging gives you correlational information, not information about cause and effect. A person might commit a crime and have a hyperactive amygdala, but whether the hyperactivity caused the crime, whether the crime caused the hyperactivity, or whether the two were caused by completely independent factors cannot be concluded from simply taking a picture of the brain.
I have declined requests to contribute as an expert witness in crimes of passion. I just don’t think we know enough at this point to make life and death decisions on the basis of what was going on in the brain during such an act. In particular, I truly believe that strong emotion can take over the brain and bias it in unusual directions. But I also think it is probably very difficult to rule out all premeditation in a crime of passion. We know that it only takes a few hundred milliseconds for brain events to reach consciousness. It takes longer than that to pick up a baseball bat or knife, or to cross the room and strangle a person. So some conscious thought has the opportunity to slip in and put on the breaks. The question is whether the emotional arousal was so great that it prevented the conscious thought from putting on the breaks, or maybe even completely prevented the infiltration of consciousness. How we would ever know what went on in those few hundred critical milliseconds?
I think the most difficult issues raised by the neuro-version of the crime of passion/insanity defense concern the nature of the self and willful self-control. When one says, “I didn’t do it, my amygdala did,” who is the “I” in question? Is that the conscious self, perhaps the prefrontal cortex? If so, maybe the argument might be that people are responsible when their conscious self (or prefrontal cortex, in a neuro version) controls behavior, but not when unconscious processes (or brain areas) control behavior. But that doesn’t really work. Much of what we call consciousness depends on underlying unconscious processes. Given this, maybe we have to conclude that we can really never know if behavior is consciously produced, and therefore should never be held responsible for our actions. Obviously, this is not a viable option. Alternatively, we could conclude that we are always responsible, in which case there is no room for a crime of passion/insanity defense.
In the end, I don’t have an answer to the crime of passion legal problem but I do have a song about it.
“Crime of Passion” by The Amygdaloids
Click here for lyrics to “Crime of Passion”
“Crime of Passion” is a classic country waltz (3/4 time) and has a traditional verse/chorus structure. I originally wrote it completely from the point of view of an inmate who had murdered his wife’s lover upon discovering her with him. Facing death, the inmate hasn’t come around and forgiven her. Quite the opposite. In the chorus he wails, “If I could go back, I wouldn’t, I wouldn’t kill for you, you’re not worth, what I’m going through.” When Rosanne agreed to sing this song with me on the record, I rewrote the lyrics in a “call and response” format. So in the recorded version you get a little taste of the wife’s point of view as well. She pipes up in the verses a bit. So when hubby says, “You were to me,” his mate completes the phrase, “like nectar to a bee.” Hubby goes on, “My source of life,” and she responds, “your loving wife.” She expresses her sorrow when she signs solo in a part of the chorus: “A crime of passion has got you, locked in that dirty old cell, A crime of passion has got you, lost in a living hell.”
Joseph LeDoux is a University Professor, Henry and Lucy Moses Professor of Science, Professor of Neural Science and Psychology and Child Psychiatry at NYU. He is also the Director of the Emotional Brain Institute at NYU and at the Nathan Kline Institute. The author of two best-selling books, The Emotional Brain and Synaptic Self, LeDoux is also a singer and song writer of The Amygdaloids, a band of scientists that plays music about mind and brain and mental disorders. The Amygdaloids‘ latest album Theory of My Mind which features the song “How Free is Your Will” is available on Amazon, iTunes, and at Amygdaloids.com.
What do you think about applying modern neuroscience to the legal system? Have a question for Joe? Let us know in the comments section below.
Podcast: Play in new window