The genetics of emotion

The dictionary defines emotion as ‘instinctive or intuitive feeling as distinguished from reasoning or knowledge’ or ‘a strong feeling deriving from one’s circumstances, mood, or relationship with others.’

Emotion is absolutely vital to human behavior and during the course of our lives, most, if not all of our actions are determined as a result of our emotional states.

Importantly, although pretty much everybody would go ‘aawwww’ after watching cat videos on Youtube, I think it’s fair to say that we different emotional beings.

These differences in emotionality mainly arise due to the variations in the neural (nerves) systems recruited to process the stimuli that trigger emotion.

While significant advances have been made to study brain circuits that process these stimuli, the paper I am presenting here today focuses on the advances made in identifying the genetic origins of individual differences in emotion processing.

Emotion genes

The key to emotional variations from person to person lie in the genes that code for proteins that take part in these complex neural circuits, the so called ‘emotion genes.’ Studying the functional variants of these genes will be crucial in understanding alterations in emotional states.

In fact, some of these genetic variations have already been described! Prime example is the gene coding for an enzyme called COMT, that metabolizes dopamine, one of the most important neurotransmitters in our bodies. Two variants of this gene have been found on amino acid 158 in COMT’s protein structure. Variants where amino acid 158 has been switched from the standard Valine to Methionine show higher anxiety compared to individuals where there is no switch of amino acids. In fact people with this variant show a number of effects that are different, including enhanced emotionality, reduced pain thresholds and increased emotional responses to pain.

This is indeed a remarkable example of how one small change in protein composition (something that arises through what is known as a single nucleotide polymorphism (SNP) can alter emotional responses. The paper then goes on to describe a few other variants in ‘emotional genes’.

Although the example I have illustrated here shows clear-cut changes thanks to one single mutation, the genetics of emotion can be way more complicated. In fact, emotion is determined by the action of hundreds of genes, complex neural circuitries and their interaction with the environment. It will be a while before we are able to disentangle these complex networks.

However, at the rate we are moving, it wont be too long before the genetics of emotion starts to unravel.

The paper can be found here