How does the brain decide to approach another individual?

Social interactions are essential for survival, development, and reproduction, yet we still know little about how the brain transforms social information into action. In a new study from the laboratory of Dr. Lilach Avitan, PhD student Imri Lifshitz and colleagues investigated how brain-wide neural activity gives rise to social approach behavior.

To study this question, the researchers developed a new experimental setup in larval zebrafish that allowed one fish to observe and respond to another freely swimming fish (Figure A) while recording the activity of thousands of neurons across its brain at single-cell resolution (Figure B). This setup enabled the researchers to track how social information is processed before the fish moves toward another individual.

The study found that a social approach is preceded by a distinct brain-wide activity pattern that appears several seconds before movement begins. Activity increased in the pallium, a forebrain region involved in higher-order processing, while decreasing in other brain regions. Together, these coordinated dynamics could predict whether the fish was about to initiate a social approach.

These neural dynamics were also related to individual differences in sociability: fish with stronger pre-approach brain activity patterns were more likely to engage in social interactions overall. The study further showed that the pallium plays a central role in shaping these dynamics and promoting the social approach.

By identifying brain-wide activity patterns that precede social behavior, this work provides new insight into how vertebrate brains convert social cues into actions and how these processes may be altered in conditions involving social deficits.