If you have ever questioned the evolutionary reasons why we tend to remember some faces more than others, a recent study published in the Journal of Neuroscience found dopamine, the pleasure hormone, to be responsible for this cognitive behavior.
Although we associate dopamine with positive feelings, what the hormone does is reinforce our organic reward system to make us more receptive to healthy lifestyles by providing positive stimuli for vital behaviors. From eating healthily, to not abusing alcohol and procreation, dopamine is responsible for a various array of cognitive processes that assure our species' survival - including the ability to recognize faces.
Facial recognition is a social and survival mechanism that allows humans and primates to identify other individuals and initiate interaction with them, and even determine is someone is a friend or a foe. This ability has made the species survive, but little is known about the brain processes involved in it.
What the new study suggests is that the ability to recognize faces is related to the natural reward system reinforced by dopamine.
The brain's fusiform gyrus has previously been documented as the portion of the neural anatomy that is responsible for recognizing faces, but it wasn't until this study that scientists have managed to formulate a firm connection between between fusiform activity and the hormone.
To show how dopamine plays a role in how people recognize faces, the researchers conducted tests involving 10 male and 10 female participants. The subjects where they were asked to remember a series of faces while the researchers monitored their neural activity vis-à-vis their dopamine levels.
The researchers used functional magnetic resonance imaging (fMRI) to monitor brain activity, which was connected to the brain's dopamine level via positron emission tomography scanning. The subjects, whose ages ranged from 22 to 30 years old, were asked to remember 24 faces shown during the tests.
The researchers found that the subjects whose brains showed a greater neural response for each dopamine unit transmitted were also the ones who were able to remember faces more easily.
"There is an intimate relationship between face recognition and the reward system. For example, you can imagine that the more sensitive someone is to social rewards, the better they feel during social interactions with familiar faces," explained Bart Rypma, co-author of the study and an associate professor at the Center for BrainHealth at The University of Texas at Dallas.
"Establishing this empirical link between fusiform activity and dopamine binding, and linking these to a cognitive process that is highly relevant for survival in a social world, was a most exciting find," added Nicholas Hubbard, co-author of the paper.
The ramifications of this finding suggest that our social endeavors are reinforced by complex cognitive reasoning. Although the clear causal mechanisms responsible for this type of brain activity remain to be further researched, this connection opens a new line of hypotheses on social activity as being organically influenced by survival mechanisms.