Animal Rights Amygdala

Your right amygdala can't
 resist the pygmy marmoset.

When you see a human face, neurons in your amygdala wake up and take note. But when you see an animal, whether cute or menacing, the amygdala in your right hemisphere jumps to its feet and starts to dance. Caltech and UCLA neuroscientists found that while pictures of humans evoked strong neuronal responses in the amygdalas of 41 human research subjects, the responses were far stronger, and faster, to images of animals. The amygdala, a two-lobed part of the limbic system buried deep in the medial temporal lobes of each brain hemisphere, is a key player in emotional reaction and processing emotional memory.

The researchers, led by Caltech postdoc Florian Mormann, suggests that we are hard-wired to respond emotionally--and thus pay close attention to--animals of all kinds. This may reflect the important role animals have played throughout human history as predators, prey, and potential allies.

The response to images of animals was especially marked in the right amygdala, perhaps reflecting the  right hemisphere's commitment to processing "unexpected and biologically relevant stimuli, or with changes in the environment," according to Mormann in the Caltech press release.

The research is open to all kinds of interpretation, but it makes one thing clear: animals are important to us. We knew that already, but still, it's interesting to see it reflected in the deepest, most primal reflexes of the old brain.

The study, like so many at the coolest edges of neuroscience today, was conducted in the brains of epilepsy patients. These generous men and women were already wired up with single-neuron-reading intra-cortical electrodes in preparation for surgery and volunteered their brains for study while they were at it.  Itzak Fried, the surgeon who installed the electrodes for this study, uses them to find the foci of his patients' seizures and to conduct other research in the meantime. He has been the key to  several other important studies, including the identification of the first human mirror neurons.

The paper was published in the August 28, 2011 issue of Nature Neuroscience.

Before You Know It, You've Decided

UCLA brain lab examines free will.

Whenever you are ready to, touch your index finger to the end of your nose. No hurry. Just do it when you want to.

Have you done it yet? No? That's fine. Take your time. But as soon as you're ready, touch your nose. Finished? Good. 

If UCLA professor Itzhak Fried and his collaborators had just now been looking into your brain--through tiny super-sensitive electrodes that pick up firing signals from individual neurons--chances are pretty good that they could have predicted when you were going to touch your schnoz before the conscious "you" did. By as much as a full second and a half! Does this call into question the freedom of your will? I don't think so; for one thing, just because a decision is not conscious doesn't mean it's not "free." Even so, showing that awareness of a decision may only arrive sometime after an action has been initiated by other parts of the brain is interesting enough regardless of what it suggests about free will. 

 
The experiment--published in the February 10, 2011, Neuron, and described by Daniela Schiller and David Carmel this week in Scientific American--went like this: Fried's team implanted electrodes into the brains of 12 epilepsy patients who were being prepared for surgery. The temporary implants were required to precisely pinpoint the areas where seizures were originating. But once in place, the researchers used the electrodes to watch individual neurons fire while asking the patients to press a button whenever they wanted to. The subjects were watching a hand sweeping around a clock face and would report to the researchers the exact time that they made the decision to push. 

Not surprisingly, the experiment engaged a lot of neurons in the supplementary motor area, a part of the frontal lobe known to be involved in movement planning. More interesting is that many of these brain cells began firing in a way that predicted button pushing a full second and a half before the person reported having made a decision. At seven-tenths of a second, there was a crescendo of neural firing, enough to let Fried's group predict the timing of the coming action with 80 percent accuracy. Not bad. 

Fried, who specializes in epilepsy surgery and neuroresearch, has long been looking at the brain for insights to questions otherwise locked in the realm of philosophy. His team identified the first human mirror neurons, sometimes described as the roots of empathy, and shed much light on the nature of memory, recognition, and other key issues. Once again patients with epilepsy, and the doctors who try to understand and help them, are pushing back the frontiers of neuroscience.