Jaak Panksepp

Jaak Panksepp coined the term affective neuroscience to describe the study of the neural mechanisms that govern emotion. He believed that animal brains shared deep, subcortical emotional systems that could be scientifically studied. His book *Affective Neuroscience* is considered a foundational text in the field.

Panksepp proposed that all mammalian brains share seven primary emotional command systems, which he capitalized to distinguish them from complex feelings: SEEKING, RAGE, FEAR, LUST, CARE, PANIC/GRIEF, and PLAY. These systems are located in deep, ancient brain structures like the periaqueductal gray. He argued these raw affects are the evolutionary building blocks of all mammalian emotion.

Panksepp famously studied rough-and-tumble play (the PLAY system) in rats, noticing that they make high-frequency vocalizations that sound like "laughter" when tickled. He showed that play is a primary process of the mammalian brain, essential for social brain development, rather than just mindless exercise. This work proved that complex social emotions could be mapped in animal models.

The SEEKING system is the brain's primary dopamine-driven motivational engine that drives mammals to explore, forage, and anticipate rewards. Panksepp argued it is not about simple pleasure, but the raw, enthusiastic drive to pursue resources. When overstimulated, it can lead to mania or addiction, and when under-stimulated, it results in severe depression.