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The Wisdom of Psychopaths
In this engrossing journey into the lives of psychopaths and their infamously crafty behaviors, the renowned psychologist Kevin Dutton reveals that there is a...
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Recently developed powerful, yet also delicate and refined, genetic tools can invasively probe nervous systems of animals, far surpassing the safer but much cruder techniques that psychologists and cognitive neuroscientists use to observe the human brain. Now in a remarkable series of experiments, researchers have located a trigger for aggression in mice—providing us with fresh insights into the workings of our human consciousness.
You might object that mice and men are not the same and that studying the murine mind is different from studying the human mind. This fact is obviously true. Yet both Mus musculus and Homo sapiens are nature’s children, sharing much perceptual, cognitive and affective processing. The same process of relentless evolutionary selection has shaped both species—our last common ancestor was a mere 75 million years ago. The structure of their brains, and of their genomes, reflects this similarity. Indeed, only a neuroanatomist can tell a rice grain–size piece of mouse cortex from the same chunk of human cortex. If you think of a mouse as a mere automaton, Google “world’s smartest mouse.” The top hit will be a YouTube video of Brain Storm, a cute brown mouse running a complicated obstacle course—crossing an abyss on a rope; jumping through hoops; going up and down a seesaw, over a pencil, up a steep incline and down a ladder; and navigating around obstacles. It hesitates on occasion, sniffs the air but, once started, speedily completes the circuit.
The amazing finesse and utility of contemporary molecular biology techniques are illustrated in recent experiments dealing with sex and power—the twin themes around which much of popular culture, psychoanalysis and art is centered.
Aggression Center
Our story starts in the hypothalamus, an ancient region of the brain, conserved throughout mammalian evolution. In humans, it is about the size of an almond, housing a motley collection of neurons. These cells regulate distinct bodily functions such as temperature, circadian rhythms, sleep, hunger, thirst, sex, anger, aggression and response to stress. Earlier work showed that electrical stimulation of some of these sites provokes cats and rats to sudden bouts of rage and that the ventromedial hypothalamus (VMH) has some involvement in sexual behaviors. Yet the precise location of attack-promoting neurons, their mode of action, and the interplay between aggression and mating—normally two opposing forms of social interactions—had remained deeply mysterious.
Enter a team from the California Institute of Technology, under the leadership of neurobiologist David J. Anderson. In four steps, the seven scientists, spearheaded by postdoctoral fellow Dayu Lin (now at New York University), nailed down the critical role of aggression neurons in the VMH. The setting was the home cage of an individually housed, sexually experienced male mouse. When another mouse, either a male or a sexually receptive female, entered the cage, the resident male mouse usually attacked the former but mated with the latter. The scientists video recorded the behavior so that the detailed time course of interaction of every pair of animals—the cautious sniffing and retreating, the pushing, shoving and biting, the mounting and consummatory activities—in hundreds of encounters could be statistically analyzed and time-aligned using software developed by machine vision engineers Piotr Dollar and Pietro Perona.
The first experiment is a molecular biology version of brain imaging. By detecting the presence of c-fos, a protein that is rapidly synthesized following neuronal activity, researchers can identify nerve cells that are involved in some behavior. Unlike functional MRI, which visualizes “voxels” of active gray matter containing upward of one million neurons, this method homes in on individual cells. A subset of neurons within the VMH, termed the ventrolateral region of the VMH (VMHvl), became active following male-male encounters that ended up in fights. Similar results occurred in males mating with females. But were these neurons the same or different cells? With help from collaborators at the Allen Institute for Brain Science in Seattle, the team applied a variant of the c-fos method that distinguishes the neurons activated in two different, successive behavioral encounters. These results indicated that, surprisingly, many brain regions surveyed contained separate but intermingled populations of neurons activated during fighting versus mating, with only a small degree (about 20 percent) of overlap.
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9 Comments
Add Commentinteresting article
Reply | Report Abuse | Link to thisNow Ii know why those cats out there do all that screeching.
Reply | Report Abuse | Link to thisNot sure this passes the sniff test.Where does one see sexual activity without some aspect of aggression? Look at life and human sexuality studies.
Reply | Report Abuse | Link to thisI think the conclusions based upon the data might be a stretch.My guess is there is both overlap and differences.I dont it is one or the other ie disagree with love not war.Oversimplified.
Yes, such kind of an off switch for sex and violence must exist. Otherwise people will stay 24 hours a day playing sex or fighting. Now we know that the switch exists, and will be learning how to operate it. Now that we found the switch what are we gonna do with it ?
Reply | Report Abuse | Link to thisWhat would have been going on in Russiam brains when they entered Berlin at the end of World War Two?
Reply | Report Abuse | Link to thisSex and aggression would seem to have become rather confused.
So the neurons governing both sex and aggression are housed in the same brain organ, the ventromedial hypothalamus (VMH). But on the one hand, it says the populations of neurons for sex and aggression are intermingled, with only a small degree (about 20 percent) of overlap, but on the other hand the article focus on neurons in a specific region, the nucleus of the ventrolateral region of the VMH (VMHvl), and only in association with aggression. So is aggression controlled specifically by the VMHvl or does the VMHvl control both sex and aggression, with intermingled populations of neurons? The technique of modifying the ion channels to be selective to blue light can't be done with intermingled populations of neurons -- or can it? It can only be targeted at all neurons in a specific region, such as the nucleus of the VHMvl?
Reply | Report Abuse | Link to thisStimulating VMHvl leads to Zombie Apocalypse...
Reply | Report Abuse | Link to thisNeuroscientists found neurons in the VMH involved in sex or violence, one or the other...girls or guns..., although initially “albeit only transiently” girls and guns, right...then girls actively suppressed the guns, ok (good plan).
What pattern of activation in the VMH would we see if the inexperienced male mouse had the option to choose - fight or f? Which urge would be stronger?
It'd be interesting to know what other areas regulate those that the researcher's stimulated in the VHMvl. If the VMH “mating neurons” that actively suppressed the “aggressive neurons” (mentioned above) were stimulated, would they silence the VMHvl neurons specifically? What other neurons and associated behaviours suppress VMHvl or aggression? Pizza neurons? What behaviours do the female VMHvls trigger when specifically stimulated? Are male VMHvls equivalent to female VMHvls? Are there developmental differences? What role do hormones play?
Let’s hope there are so many more brain areas dedicated to peace and love, or at least that we evolve some more soon. =o) There's a fair few people on this planet - mating neurons definitely working AND people spend a great deal of time trying to kill each other...seems we are not so different from a bunch of angry mice with overactive VMHs!
PS I'd be pretty angry if they infected a blue strobe light into my brain...no matter where they put it. Poor lil dudes!
My essay, 'The chip in the brain', which you can access at the FQXi web site, outlines an alternative to the 'neural network' model. Background at www.scienceuncoiled.co.uk.
Reply | Report Abuse | Link to thisMichael T Deans, MA MSc
A bit behind on this boat, but I think you have large amount of questions that need to be added and applied to this article. I guess that is what commentary is for. Nice job, article would have been incomplete without it.
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