NEUROSCIENCE

Rendezvous in Hedonia

Morten Kringelbach © Isak Hoffmeyer
Morten Kringelbach
© Isak Hoffmeyer
Looking at a baby (superior image) instantly triggers neural activity in a specific area of the medial orbitofrontal region of our brain. This does not happen when looking at an adult. Morten Kringelbach’s team sees such a signal as a
Looking at a baby (superior image) instantly triggers neural activity in a specific area of the medial orbitofrontal region of our brain. This does not happen when looking at an adult. Morten Kringelbach’s team sees such a signal as a "reward", as a sort of "parental instinct" programmed in our neurons. In a different region of the brain, the fusiform face area (inferior images) points to another form of recognition, used when looking at either adults or children.
Source: Morten Kringelbach

Understanding the nature of pleasure in order to be able to treat affective disorders: this is the quest of Morten Kringelbach and his TrygFonden Research Group. “The lack of pleasure is a very common problem in mental illnesses such as depression. By better understanding the brain circuitry that pleasure is dependent on, we hope to be able to restore the balance of these fundamental brain networks in the short and long term”, says the Oxford University (UK) and University of Aarhus (DK) neuroscientist. Let’s take a look at this adventure in Hedonia, the land of hedonism.

Food, sex and social life

“Our basic pleasures are caused by feelings intimately related to food, sex and social interaction. On a neural level, such sensations are first detected by sensory receptors located throughout the body. These are then decoded in the sensory regions of the brain”, says psychiatrist Morten Kringelbach(1). And contrary to what one might imagine, pleasure is not just a mere stimulation of such receptors, but the result of interactions between anticipation, evaluation and stored away sensations. Pleasure can therefore be seen as a sweet mix of desire, pleasant sensations and learning.

“Several studies conducted on humans and animals have pinpointed the brain regions crucial for this mix. Some are buried deep in the brain, such as the nucleus accumbens or the hypothalamus, while others are located in the cerebral cortex.” This is the region of the brain the TrygFonden Research Group researchers are concentrating on. Consisting of 10 scientists from Oxford University and the University of Aarhus, the research team is multidisciplinary and international. Neuroscientists, physicians, psychologists, engineers and computer scientists from Scotland, Ireland, Denmark, Bangladesh, France, England, Germany and South Africa are collaborating to better understand pleasure, our pleasure.

“Our work is mainly focused on the study and understanding of the functional anatomy of the human brain. To do this, we use stateof- the-art neuroimaging techniques such as magneto-encephalography (MEG).” With such techniques, the researchers hope soon to reveal the as yet undiscovered role of the orbitofrontal cortex, located just behind the eyes. Why this particular area? Because it is significantly bigger in human beings than in other primates. But in terms of hard facts, what can we learn from this area and how can it be useful from a medical standpoint?

Children’s faces

A baby’s face has always attracted more attention than an adult’s. Most of us will be more enraptured by a close relative’s offspring than by his or her new friend! For Morten Kringelbach’s team, understanding this phenomenon presented an opportunity to help women suffering from postnatal depression. Aided by fellow researcher Alan Stein and other colleagues, Morten Kringelbach and his team examined the brain activity of men and women when shown pictures of children’s and adults’ faces. The result: researchers detected a surge of activity in the medial orbitofrontal cortex just one seventh of a second after showing someone a child's face. By contrast, no such observations were made when showing adult faces.

“The medial orbitofrontal cortex is clearly responsible for a reward mechanism and it is quite possible that babies’ faces and social pleasures in general are good for our wellbeing.” It has been found that women suffering from ‘baby blues’(2) fail to react like other women to babies’ faces, even when their own baby is involved. “Activity in this brain region may change during postnatal depression. This could serve as a warning signal, helping to identify and treat women susceptible to this type of depression. In addition, treating mothers and fathers suffering from baby blues would help reduce the risk of their own children ending up suffering from depression.”

The pleasures of eating

Kringelbach and his colleagues are also interested in the vital role played by food in survival and pleasure. As part of the research conducted in this area, they have identified a network of brain regions, again including the orbitofrontal cortex, which appears to drive us to seek the pleasure of eating. “An imbalance in this network would seem to be a likely cause of eating disorders”, says the researcher, who has also sought to understand why we always have a little room left for a dessert at the end of a meal even when we are full up. “We have found that the orbitofrontal cortex is primarily responsible and that its activity is linked to our subjective attraction to food.” In addition, researchers have shown that this region is involved in the subjective experience of all forms of pleasure, including those provided by drugs, music and orgasms. “This all leads us to think that the orbitofrontal cortex may have a role to play in treating eating disorders and other addictive behaviour.”

Deep cerebral stimulation

“Stimulating specific brain regions in animals or human beings may lead to immediate changes in the sensation of pleasure and desire.” Tipu Aziz, an Oxford University neurosurgeon, has demonstrated that deep brain stimulation in the grey matter significantly reduces pain in chronic pain patients. However, for such a discovery to be useful in the long term, we need to know how the stimulation affects the brain. Using magneto-encephalography, Morten Kringelbach’s team has examined closely the action of deep brain stimulation, observing a specific activation of the brain network involved in emotion. Here again, the orbitofrontal cortex is involved.

“What is particularly interesting in the context of this project is that the same results have been observed in people suffering from depression.” Furthermore, deep brain stimulation can be used in treating many pathologies like dystonia, Parkinson’s disease, obsessive compulsive disorders, palsy, etc. “For this technique to be effective, it is crucial for us to know the exact role of each brain region, and which region needs stimulating to alleviate the symptoms of a particular disease.”

Élise Dubuisson

  1. All quotes are from Morten Kringelbach
  2. A much-used expression for postnatal depression.

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From pleasure to empathy…

With Morten Kringelbach interested in people having difficulty experiencing pleasure, Tania Singer and her colleagues at the University of Zurich are focussing on the feeling of empathy. This team of researchers believe that, in a society where crime and human rights violations are on the increase, the ability to influence the capacity for empathy could be beneficial.

The project, running under the name EMPATHICBRAIN, is looking into the possibility of strengthening our ability to understand our own feelings and those of others. Tania Singer is attempting to find an answer to this question using an innovative multidisciplinary approach. EMPATHICBRAIN is in fact a mixture of neuroscience, economics, psychology and psychobiology (the study of the relationships between the psyche and biological functions).

The first step of this long journey to the heart of the brain involves detecting functional and structural differences in the brains of people with a distinct capacity for empathy. However, the researchers are not just content with making observations. They are also developing a whole learning programme for empathy, cultivating equanimity, empathic joy, compassion and loving kindness .

www.forschungsportal.uzh.ch/unizh/p11582.htm


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