Subtitles: WDR mediagroup digital GmbH on behalf of WDR
When the artistes of the Circus FlicFlac
perform their stunning acrobatics, it's all a question of nerves.
Because without strong, well-functioning nerves,
such perfect body control would be simply impossible.
The young stars on the programme are Tatjana Kastein and Alona Jouravel,
both 15 years old.
The 2 hand-stand specialists maintain their balance
even when they're upside down.
This is made possible by the network of nerve tracts
that runs throughout the human body.
They transmit commands to the muscles which move the trunk,
the arms, and the legs.
Tatjana and Alona train with great enthusiasm,
and have done ever since they were children.
I've been an artiste now for 2 years.
But I've been training for much longer.
Ever since I was 6, in fact.
I find things a lot easier now than I used to.
Far less strenous. You just do things automatically.
But what's behind these fascinating movements,
indeed behind ordinary, everyday movements?
Alona has come to the laboratory of the Vitronic company
to act as a test person.
Her body is being scanned with a laser scanner.
The data obtained are then used to produce a 3-D image of the girl.
A computer animation enables us to look inside the artiste's body.
It shows the typical structure of the human nervous system.
The brain and spinal cord together form the central nervous system.
Nerves lead out from it to the organs and limbs.
Electrical impulses travel along the nerve fibres.
They ensure the interplay of the body's functions,
and of its movements.
At Mannheim University Hospital neurologist Johannes Binder
is exciting those areas of the brain which control Alona's hand.
Electrodes attached to her fingers measure her reactions.
In this way the doctor tests the conductive capability of her nerves.
Everything is fine, as we see from the graphs,
and from another test.
A light tap on the patellar tendon fails to produce any reaction.
But a slightly firmer tap causes Alona's lower leg to jerk up.
This shows that her spinal cord is in proper working order.
Using another 3-D model
we show what happens in this case inside the human body.
Tensioned by the blow,
the patellar tendon pulls on the extensor muscle of the thigh.
The extension stimulus is transmitted to the spinal cord
which reacts immediately to the alarm signal,
sending nerve impulses
to the flexor muscle below the knee and the extensor muscle above it.
The upper muscle contracts, the lower one stretches.
The muscles react to the stimulus without the brain being involved.
The patellar reflex is a standard test.
Reflexes protect us from injury.
Alona withdrew her hand automatically.
Reactions to stimuli can be observed in all living creatures.
When Alona touches the trigger hairs inside a venus fly trap,
the lobes, as they are known, snap shut.
Normally, this mechanism is used to catch insects.
A snail's feelers also react to stimuli.
They possess real nerve cells,
although their structure is a little simpler than in humans,
who belong to the vertebrates family.
Even so, the basic structure of all nerve cells
is already present in invertebrate creatures like the snail.
Nerve cells have branched projections,
rather like antennae with which they receive signals.
These projections are known as dendrites.
The word comes from Greek and means "tree-like".
Information is passed on by a long,
electrically conductive nerve fibre called an axon.
The task of transmitting signals to the receiver
is performed by presynaptic terminals, as they're known.
They take their electrical message to its destination
which can include muscle cells.
When a dendrite receives a stimulus that is powerful enough,
a kind of chain reaction takes place.
A succession of impulses
travels along the axon to the presynaptic terminals.
In this case they excite a muscle.
Alona and Tatjana attend the circus's school.
Every morning it's their "grey matter" that's trained.
Today, teacher Monika Lazar
wants to show the class how nerve cells function.
And she's thought up something special.
Outside the mobile classroom
she has the youngsters erect a row of dominos.
The effect when one is tipped over
is very similar to what happens in the simple cells of intervebrates.
Once again, in slow motion.
Step by step: This is how information is passed on.
Acrobats perform their tricks at high speed
to give the audience a real thrill.
When Malte Knapp is on his wacky unicycle
he has to have lightning reactions.
This involves nerve fibres of a more complex structure.
In vertebrates, in other words, in man as well,
large sections of each axon are sheathed in an insulating layer.
Located inbetween are non-insulated areas called the nodes of Ranvier.
Jumping from node to another,
the nerve impulses reach their destination much faster
than in the case of invertebrate creatures.
In this model, the insulation is represented by red rods,
the nodes of Ranvier by dominoes.
The first domino is about to fall against a rod
which will then knock over the next domino.
The race between the 2 nerve cells in slow motion.
The vertebrate model at the front is distinctly faster
than the model at the back which represents invertebrate creatures.
Tatjana is working on a new element of her act.
In contrast to the reflexes
with which we react automatically to external stimuli,
voluntary sequences of movements have to be learnt.
We're helped in this by the brain.
It processes information which we perceive with our senses.
Tatjana's sense of touch, for instance,
registers the slightest change in the pressure on her hands.
Nerve cells continuously report these signals to the brain
which emits the necessary control commands via nerve tracts
leading to the arms and legs.
As a result, the artiste can adjust her movements
so that she always maintains her balance.
It will take weeks and weeks of practice
before Tatjana can perform her new element to perfection.
Alona is on her way to see Dr. Kristina Szabo.
This room contains a magnetic resonance tomograph.
It enables the brain to be watched "at work", so to speak.
We're interested in what goes on in Alona's head
when she carries out certain movements.
She can't do a handstand here.
So she has to be content with simpler actions.
Please open and clench your right fist.
When this movement is performed,
millions of cells in the brain are active.
They're located in the area shown in orange.
Now waggle your left foot, please.
When Alona's brain gives the command "waggle left foot",
nerve cells in another area become active.
A comparison:
On the left is the foot. The hand is on the right.
The brain consists of billions of nerve cells
that have to communicate with one another.
This communication takes place at special contact points
known as synapses.
When a nerve cell is excited electrically,
the presynaptic terminals produce chemical messenger substances
which transmit the information.
On the receiver side,
this information is again converted into an electrical impulse.
This impulse travels along the axon to the next presynaptic terminal.
So nerve cells can communicate in 2 ways:
chemically and electrically.
When Alona and Tatjana warm up before a performance,
they're not just loosening their muscles.
They're also recalling from memory the movement patterns
they'll need for their appearance.
Through their intensive training,
they have stored programmes in their brains.
As a result, they no longer have to think about every detail
in order later for the show to run smoothly.
Alona in a rotating metal frame.
Handstand acrobatics of the highest level.
The artiste demonstrates in impressive fashion
what extraordinary achievements are possible
through the virtuoso interplay of the brain, the spinal cord,
and the nerve tracts.
A nerve network which, in some mysterious way,
organizes itself and is one of the greatest wonders of nature.
Copyright WDR 2015