Emotions are generated in the limbic system, a phylogenetically ancient part of the brain. Fear and disgust, but also joy or grief, are very difficult to suppress. And because they are so strong, feelings can also be a burden in life – for instance when people suffer from depression or anxiety disorders.
For science, emotions are a challenging area of research. The thing is, they are highly individual and often difficult to describe. The best-studied emotion is fear. Individual emotionality is an important part of our personality. Experiences in our lives and events that are associated with strong emotions, remain particularly deeply anchored in our memories: we remember our first love for our entire lifetime.

The love of our life – is it all just chemistry?
In that thrilling time of falling in love, the neurotransmitter dopamine floods the brain. It is secreted by the hypothalamus, the brain’s most important hormone source. Dopamine acts primarily on the limbic system and also plays a major role in reward and euphoria. When we are in love, the body produces fewer stress hormones, wounds heal faster and pain is perceived less intensely. But at some point the dopamine level drops again and the “in-love” feeling can become enduring love. Now oxytocin plays a greater role. It's produced in the hypothalamus and stored in the pituitary gland. The hormone has a calming effect, reduces anxiety and aggression, and fosters feelings of closeness and trust. Physical contact is a stimulus that can cause production of oxytocin and dopamine – even if that first period of being in love passed a long time ago.

Run away or not? / Fight or flight?
Emotions trigger specific behaviour patterns. Fear for instance prepares the body for fight or flight: the heart rate and blood pressure rise, the muscles are supplied with energy, attention is concentrated on the threat. That can be very helpful or also absolutely useless – depending on the situation. Our own emotions and experiences need to be weighed up alongside the other person’s behaviour so we can react appropriately. The insular cortex, part of the cerebral cortex, plays a key role here. Nadine Gogolla and her research group at the Max Planck Institute of Neurobiology are investigating exactly what happens there. As is often the case in brain research, the scientists here are working with mice as a model. During their research they discover that mice, just like humans, have facial expressions from which emotions like joy, disgust and fear can be reliably detected. With the help of a recently developed computer-aided facial expression analysis tool, researchers can now measure the intensity and type of an emotion and compare it with the activity of nerve cells in a particular brain region.

Emotions in society
What a person feels – and the way they show or are permitted to show that towards another person – is not just an expression of an inner state, it’s also a learned behaviour and society influences how it is defined. So do emotions have a history? Do emotions even write history? Ute Frevert and her team at the Max Planck Institute for Human Development in Berlin are looking into these questions. After all, emotions like fear, anger and hope have a significant influence on politics and society as well. For instance, the researchers have analysed the meaning of shame, disgrace and public humiliation in different cultures and periods. These emotions still play a major role today: new shaming platforms are popping up almost daily on the internet. Cyber mobbing affects children and young people in particular. And insights into the different impacts of emotions are very important for living together in multicultural societies.

Soundcheck – music or noise?
Where music is concerned, everyone knows that tastes are different. But everyone can say immediately whether or not they like a piece of music. Researchers at the Max Planck Institute for Empirical Aesthetics in Frankfurt want to find out what the deciding factors determine whether someone finds music pleasant or unpleasant. To do this, they use the ArtLab, a multifunctional event space that serves as a concert hall and laboratory all in one. Sounds, facial expression and body language, as well as various physical data about the artists and up to 46 listeners, can be captured and evaluated there.

The singers in a vocal ensemble rehearse at the  Frankfurt ArtLab. Information such as EEG, ECG and respiratory rate are recorded © Max Planck Institute for Empirical Aesthetics, Frankfurt / Jörg Baumann

Max Planck scientists from Leipzig on the other hand want to find out what makes a pop song successful. Whether or not a piece of music becomes a hit is not so much down to the lyrics or tune, it’s more about the chord sequences. Especially popular songs are characterised by a mixture of predictable and surprising chord sequences. The fact is that only this combination activates the brain’s pleasure system. That also explains why we often feel better immediately after listening to the “right” music.

Love, fear, anger, sadness and joy – what’s going on in our heads?

Love
If you fall in love, the reward system in the brain is activated. A number of hormones such as dopamine, vasopressin and oxytocin are produced. The limbic system is key for the production of these positive emotions. It consists of neurons that use a neurotransmitter called dopamine. The cell bodies of these neurons are located in the brain stem, extend through the amygdala and the hippocampus and finish up in the basal forebrain in the nucleus accumbens – the reward system.

Fear
The amygdala decides in a few milliseconds whether or not we experience fear. The heart beats faster, the muscles receive more energy – we’re ready for fight or flight. The amygdala is located in the temporal lobe and is connected to the brain stem. Thus it influences the autonomous functions of the body, like breathing and circulation. A particularly thick nerve bundle leads to the hypothalamus, which triggers adrenaline production. The amygdala receives information from all the sensory regions in the cerebral cortex. The frontal lobe compares the sensory signals with past experiences and can curb the activity of the amygdala.

Anger
If we are insulted, the information is initially sent via eyes and ears to the interbrain, which passes it on to the amygdala and the frontal lobe of the cerebral cortex. But if the “emotional” amygdala decides this is something offensive, then the “rational” cerebral cortex doesn’t stand a chance: the amygdala is faster. It activates the hypothalamus, stress hormones like adrenaline and noradrenalin are secreted, the pulse rises rapidly. The limbic system ensures that this anger becomes visible too: voice, expressions and body language express that.

Sadness
If someone leaves us or a loved one dies, we feel great sadness. In the brain this causes a stress reaction. The amygdala alarm system is activated and the stress hormone cortisol is released. Grieving is a conscious emotion though. It helps us to process the stress and live with the experiences of loss. In grief, areas of the brain located in the frontal lobe are activated. They act on the amygdala to bring about a renewed state of relaxation.

Joy
Contentment, joy and happiness are closely linked with each other. Contentment is a state of inner balance that’s partly genetic and partly influenced by the environment. It is formed between the ages of five and ten, and remains largely unchanged throughout life. In biochemical terms three neurotransmitters are particularly involved: serotonin, dopamine and oxytocin. The brief high of happiness is caused by a cocktail of the brain’s own natural opioids, such as endorphin. The crucial factor for the quality of happiness is the origin of the joy. Material objects like a new item of clothing primarily activate the reward system. This feeling of happiness is only short-lived. In contrast social rewards, such as appreciation and friendship, have a longer lasting effect.