Feelings are personal and subjective, just like all of psychology, but the human brain turns them into a standard code that objectively represents emotions across different senses, situations and even people, according to a new paper.

The authors set out to gain insight into how the brain represents our innermost feelings – what they call the last frontier of neuroscience – and upend the long-held view that emotion is represented in the brain simply by activation in specialized regions for positive or negative feelings. 

"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 senior author Adam Anderson, associate professor of human development in Cornell University's College of Human Ecology. "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 says.

How the brain processes emotion. Credit: Cornell University

For the study, the researchers presented participants with a series of pictures and tastes during functional neuroimaging, then analyzed participants' ratings of their subjective experiences along with their brain activation patterns.

They found 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), suggesting, the authors say, that representation of our internal subjective experience is not confined to specialized emotional centers, but may be central to perception of sensory experience.

"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," Anderson explains.

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), they say. 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 concludes.