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SWEAT
He is coordinating a project called POTION which is researching these chemosignals . The researchers use videos to induce fear or happiness in people , and then collect their sweat to analyse which chemical compounds are released with each emotion .
‘ The next step is to synthesise the odours and … investigate how they induce emotions in others ,’ said Prof . Scilingo .
Eventually , fear odours and people ’ s responses to them could be used to help psychiatrists understand more about different aspects of phobias and depression . And happiness odours could be used to help in treatment .
‘ If we can use the odour of happiness in addition to the usual treatment for phobias or depression , we ( could ) increase the efficacy of the therapy ,’ said Prof . Scilingo .
The POTION researchers are also investigating how odours impact people ’ s social interactions , and sense of inclusion or exclusion from others .
Previous research has found that a person ’ s emotional state can influence how they respond to other people – and how others respond to them , Prof . Scilingo says . Someone feeling fear is less likely to approach or trust people , and others are likely to be wary of them . And the reverse is true for happiness – the happier someone is , the more likely they are both to trust others and to attract them , says Prof . Scilingo .
MAMMALS
In mammals , the sense of smell is uniquely linked to the part of the brain associated with emotions and the creation of memories , says Dr Lisa Roux , researcher at the Interdisciplinary Institute for Neuroscience in France .
Smell is important for recognition between people . A mother can recognise the smell of her child , for example , and this may be an important part of bonding , she said .
‘ We humans use our sense of smell more than we think . It ’ s more unconscious , and a little bit taboo – we are not very comfortable with it – but there is more and more evidence that smell is important in social behaviours ,’ said Dr Roux .
The first region of the brain that processes chemosignals – the olfactory bulb – is directly connected to the limbic system , which controls the ability to identify another individual , the formation of memories , and manages emotional responses . All other senses – taste , hearing , sight and touch – are processed by other regions of the brain before being linked to the limbic system .
This may be because smell has been the most important sense for the survival of species . ‘ Chemical signalling is very important , even for bacteria . It ’ s a very ancient modality , it ’ s really key ,’ Dr Roux said .
PLEASURE AND PAIN
The sense of smell is linked to pleasure and depression , possibly because of its unique link to the limbic system .
Up to a third of people with a defective sense of smell experience symptoms of depression , according to a research paper published in 2014 .
This may be partly because of their loss of sense of taste , and concerns about personal hygiene and social interactions . But it is also likely that olfactory loss affects the brain ’ s functioning and in particular its emotional control , authors of the paper said .
‘ This might be because the olfactory system is directly linked to the limbic regions – which include the amygdala that is very important for controlling emotions ,’ said Dr Roux .