Although feelings are personal and subjective, the human brain turns them into a standard code that objectively represents emotions across different senses, situations and even people, according to a new study.
"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," said Cornell University neuroscientist Adam Anderson, senior author of the study.
"Population coding of affect across stimuli, modalities and individuals," said Anderson.
The findings provide insight into how the brain represents our innermost feelings and upend the long-held view that emotion is represented in the brain simply by activation in specialised regions for positive or negative feelings, he said.
"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," Anderson said.
The researchers presented participants with a series of pictures and tastes during functional neuroimaging, then analysed 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, that representation of our internal subjective experience is not confined to specialised emotional centres, 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), they said.
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 said.
The research was published in the journal Nature Neuroscience.