The human brain processes emotions by turning them into a standard code that objectively represents feelings across different senses, situations and even people, according to a new study.
Although feelings are personal and subjective, Cornell University neuroscientist Adam Anderson has debunked the long-held view that emotion is represented in the brain simply by activation in specialised regions.
"We discovered that fine-grained patterns of neural activity within the orbitofrontal cortex, an area of the brain associated with emotional processing, act as a neural code which captures an individual's subjective feeling," says study author Anderson, a associate professor of human development in Cornell's College of Human Ecology.
Their findings provide insight into how the brain represents our innermost feelings – what Anderson calls the last frontier of neuroscience.
"If you and I derive similar pleasure from sipping a fine wine or watching the sun set, our results suggest it is because we share similar fine-grained patterns of activity in the orbitofrontal cortex," Anderson said.
"It appears that the human brain generates a special code for the entire valence spectrum of pleasant-to-unpleasant, good-to-bad feelings, which can be read like a 'neural valence meter' in which the leaning of a population of neurons in one direction equals positive feeling and the leaning in the other direction equals negative feeling," he explained.
For the study, the researchers presented participants with a series of pictures and tastes during functional neuroimaging.
The participants' ratings of their subjective experiences were then analysed along with their brain activation patterns.
The results showed that valence was represented as sensory-specific patterns or codes in areas of the brain associated with vision and taste, as well as sensory-independent codes in the orbitofrontal cortices (OFC).
According to the authors, this suggests our representation of our internal subjective experience is not confined to specialised emotional centers, but may be central to perception of sensory experience.
They also discovered that similar subjective feelings – whether evoked from the eye or tongue – resulted in a similar pattern of activity in the OFC, suggesting the brain contains an emotion code common across distinct experiences of pleasure or displeasure.
Furthermore, these OFC activity patterns of positive and negative experiences were partly shared across people.
"Despite how personal our feelings feel, the evidence suggests our brains use a standard code to speak the same emotional language," Anderson concluded.
The findings are published in Nature Neuroscience.