NICHOLAS SPITZER is a professor of neuroscience at the University of California. His research concentrates on the ways in which neurons take on specialised functions to enable signalling in the brain. He is editor-in-chief of BrainFacts.org, a public information service about the brain and nervous system, and is instrumental in the BRAIN Initiative, a research project backed by the White House to advance new technologies to help map the brain. What do you know about the brain that the rest of us don’t?

The structure and function of the brain are determined by genes and environment. We think we know this—it’s nature and nurture—but what many don’t realise is that this remains true throughout life. People think the brain is malleable only when we’re young. But that’s just not true. The forms of plasticity we see in the young brain are sustained in the mature brain. By plasticity I mean the ability of the brain to change its structure and function in response to changes in the environment. In addition to the classical ways the brain changes (the strength of the connections, synapses and neurons) we now understand a third kind of brain plasticity in which the neurotransmitter molecules—the signals from one neuron to another—can actually switch.

Suggested Reading: “Neurotransmitter Switching in the Adult Brain Regulates Behaviour”, Science, April 26th 2013

What does this mean for human development?

Our experiments have mainly been done on adult rats. A finding that is directly related to the human condition is that putting the animals on different photoperiods [day and night cycles] changes the neurotransmitter identity in the hypothalamus [a part of the brain] and this changes the animal’s behaviour. When animals are on a short day (rats are nocturnal so a short day is good) they make dopamine, the reward chemical. On the long day the neurons switch from dopamine to somatostatin, which retards growth.

We test the behaviour with a simple maze that has a dark side and a light arm. When they have the dopamine from the short day they waltz around in the light arm, but during the long-day cycle they hide out in the dark side. Their anxiety or confidence depends on the neurotransmitters which, in turn, depend on the light experience.

We think this is related to Seasonal Affective Disorder. (I did my PhD in London and remember the short winter days very well!) The treatment for SAD is no longer drug therapy, but light.

Why do humans become depressed when it gets dark?

We have to speculate a bit here, but the idea is that during the winter months back in the days when we had a very seasonally driven existence it was perhaps useful to be quiet, withdrawn and sleeping a lot. In the summer months when the spring arrives you want to run outside and be active.

So we are conserving energy and not consuming our resources?

Exactly. There is evolutionary rationale for this kind of change in the brain. The rewiring of the brain can occur in seconds as we change the neurotransmitters and neuromodulators, such as dopamine and serotonin. The metaphor that’s useful is a railway switching yard—the trains come into the yard and depending on the switch they can go off to Manchester or down to Bangor. These neuromodulators route the brain’s electrical activity. The circuitry doesn’t change but the route does.

What difference does that make to the person?

The bottom line is generation of behaviour. That is the purpose of the brain. This rewiring, which occurs on a very rapid timescale and is completely reversible, changes behaviour. This flexibility of the nervous system makes the BRAIN Initiative project wonderfully complicated. It is not one set of wires, or one computer we’re trying to map, it is multiple computers. And we can change the wiring to produce different behavioural outcomes.

But doesn’t behaviour itself generate neurotransmitters like dopamine?

Yes. It is a closed loop system. The transmitters generate behaviour and the behaviour in turn shapes the brain and generates the transmitters. The brain changes itself through its own activity.

Suggested reading: “The Brain That Changes Itself” by Norman Doidge

So an infant that is well-cared for, with a brain full of dopamine, will form a different brain to an infant that has bad experiences?

That’s right and we know that at a variety of levels. We know this from children’s homes in the Soviet Union who had limited intervention and we know from rats and mice that environmental enrichment determines how the brain develops.

So the most important thing for the growing brain is interaction with the mother?

Absolutely. You can replicate this maternal deprivation by taking young rats away from their mothers and their nervous systems do not develop normally. It’s a very clear connection. It’s fascinating the way in which the electrical activity of the brain shapes behaviour and also shapes the brain. It’s a remarkably self-organising structure.

Suggested Reading: “Train Your Mind, Change Your Brain” by Sharon Begley

Would your brain look different on a scan if you have grown up in a Soviet orphanage?

Yes. But let me dispel a brain development myth. Many people think classical music is going to enhance brain function (the Mozart effect) or playing particular games sharpens ones cognitive function. These theories have been looked at in detail and they don’t stand up. It is disappointing in a way, but what we have learned is that exercise is the key thing for brain function.

Doing crosswords isn’t good for your brain?

It is good for improving your crossword skills but does it lead on to other kinds of advanced cognitive function? No. There is no translation of the crossword skills to other skill categories. That shouldn’t discourage anyone, they are a lot of fun, but a vigorous hike will do more for your cognitive function.

What about playing an instrument? Don’t you have to use right and left brain for a stringed instrument?

Yes. That has clear cognitive functions that do crossover. Especially learning to play and read the music at the same time. But exercise is number one, diet number two and then social interaction. These are the important things for brain function.

Suggested Reading: “How We Decide” by Jonah Lehrer

What do you do to protect your brain?

I’m a rock climber and an ice climber. I go to the Sierra Nevada mountains, anywhere above 10,000 feet I’m a happy guy. At home I go to the gym.