Prefrontal cortex is an interesting brain area.

And you do that by measuring the relative activation of the left prefrontal cortex in the fMRI, versus the right prefrontal cortex.

So you have the prefrontal cortex here, lighting up in red.

One of the brain regions that changes most dramatically during adolescence is called prefrontal cortex.

So this is a model of the human brain, and this is prefrontal cortex, right at the front.

And so we had this focal area called the medial prefrontal cortex that went way up in activity.

This is an area in the prefrontal cortex, a region where we can use cognition to try to overcome aversive emotional states.

It goes to the nucleus accumbens, all the way up to the prefrontal cortex, orbital frontal cortex, where decisions are made, high level.

The arrows indicate peak gray matter volume in prefrontal cortex. You can see that that peak happens a couple of years later in boys relative to girls, and that's probably because boys go through puberty a couple of years later than girls on average, and then during adolescence, there's a significant decline in gray matter volume in prefrontal cortex.

So in my lab, we bring adolescents and adults into the lab to have a brain scan, we give them some kind of task that involves thinking about other people, their minds, their mental states, their emotions, and one of the findings that we've found several times now, as have other labs around the world, is part of the prefrontal cortex called medial prefrontal cortex, which is shown in blue on the slide, and it's right in the middle of prefrontal cortex in the midline of your head.

We had this broad patch of area called the lateral prefrontal cortex that went way down in activity, and I'll summarize that for you here.

In red is an area that active in the prefrontal cortex, the frontal lobe of the brain, and in blue is this area that was deactivated.

In very short, people who have more activity in the right side of the prefrontal cortex are more depressed, withdrawn. They don't describe a lot of positive affect.

And when you're happy what we call positive valence you squirt dopamine into the prefrontal lobes, which makes you a breadth first problem solver you're more susceptible to interruption you do out of the box thinking.

The reptilian part of our brain, which sits in the center of our brain, when it's threatened, it shuts down everything else, it shuts down the prefrontal cortex, the parts which learn, it shuts all of that down.

Unfortunately for America s children, the high functioning circuits in the caregiver s prefrontal cortex that these skills demand are directly affected by stress. And, in the US, the vast majority of early childhood workers are under enormous economic stress.

Why do teenagers seem so much more impulsive, so much less self aware than grown ups? Cognitive neuroscientist Sarah Jayne Blakemore compares the prefrontal cortex in adolescents to that of adults, to show us how typically teenage behavior is caused by the growing and developing brain.

You prune away the weaker branches so that the remaining, important branches, can grow stronger, and this process, which effectively fine tunes brain tissue according to the species specific environment, is happening in prefrontal cortex and in other brain regions during the period of human adolescence.

Now that might sound bad, but actually this is a really important developmental process, because gray matter contains cell bodies and connections between cells, the synapses, and this decline in gray matter volume during prefrontal cortex is thought to correspond to synaptic pruning, the elimination of unwanted synapses.

So what happens when we pay attention is that the prefrontal cortex, the sort of executive part of our brains, sends a signal that makes a little part of our brain much more flexible, more plastic, better at learning, and shuts down activity in all the rest of our brains.

But it is an extraordinary statement for a religious leader to make, because it sets to one side the question of the truth or falsehood, or the ethical value, of religious beliefs. Or rather all that wiring in the prefrontal cortex must be ethical, because it is good for survival.

Data obtained from animal experiments show that harmful physiological changes result from the inability of the brain and body to respond to repeated stress with adaptive modifications in structure and function. Three brain areas the hippocampus, the prefrontal cortex, and the amygdala are particularly susceptible to pathological changes in size and function.

This region is more active in adolescents when they make these social decisions and think about other people than it is in adults, and this is actually a meta analysis of nine different studies in this area from labs around the world, and they all show the same thing, that activity in this medial prefrontal cortex area decreases during the period of adolescence.

And this region, the regions within the limbic system, have been found to be hypersensitive to the rewarding feeling of risk taking in adolescents compared with adults, and at the very same time, the prefrontal cortex, which you can see in blue in the slide here, which stops us taking excessive risks, is still very much in development in adolescents.

Similarly, there is evidence that the prefrontal cortex a key structure in emotional regulation as well as in decision making and working memory shrinks in major depression. On the other hand, rather than atrophying, the amygdala, the seat of emotional memories, becomes hyperactive both in post traumatic stress disorder and depressive illness, and there is evidence from animal studies of a hypertrophy of nerve cells after repeated stress.