Every complex organism has a control center. In humans, that center isn’t just the prefrontal cortex — it’s far deeper. The motivational core of who we are is nestled in the midbrain, in a small, ancient structure called the nucleus accumbens.
This is where drive begins. “The nucleus accumbens is central to motivation and reinforcement learning,” write Salamone and Correa (2012). Without this core, there is no pleasure, no desire, and arguably, no self.
Long before we evolved into Homo sapiens with abstract thoughts and social networks, we were driven by one thing: movement toward reward. Hunger, reproduction, and survival all required one thing — motivation. And that, quite literally, originates in the midbrain.
The self doesn’t need language to exist. Think worms. Even they show basic motivation. In fact, researchers have found that “motivational systems are evolutionarily conserved across species” (Panksepp, 1998). The worm doesn’t think — it seeks. And what it seeks is determined by rudimentary neurology that resembles our own motivational engine.
So much of what we interpret as conscious choice is prewired by circuits in the thalamus and nucleus accumbens. These structures tag memories with emotional relevance — a process essential for survival. According to Rolls (2013), “emotion-related learning gives priority to information that is biologically significant.”
Basic memory in the midbrain encodes location and valence — the “where” and “was it good or bad?” That’s enough to find food and avoid predators. But one floor up, still hardwired into the midbrain, is the ultimate biological drive: reproduction.
Sexual motivation is not just one drive among many — it is the evolutionary endgame. Once an organism has fed and survived, its genes demand passage to the next generation. Everything else is optional.
In modern life, the struggle to feed oneself has become trivial. Most humans no longer fight daily battles against predators or starvation. What remains? Sex. And its neurochemical promise of reward.
Sigmund Freud wasn't wrong. Much of human ambition — careers, fame, wealth — can be reframed as secondary strategies in the competition for reproductive success. As Freud (1920) put it, “sexuality is the key to understanding the entire psychic life of man.”
The modern cortex may pretend to be in charge, but it’s merely justifying what the midbrain already decided. The “self” — the motivational self — resides not in lofty thought, but in ancient brain structures that predate speech and reason.
Freud, S. (1920). Three Essays on the Theory of Sexuality. Basic Books.
Panksepp, J. (1998). Affective Neuroscience: The Foundations of Human and Animal Emotions. Oxford University Press.
Rolls, E. T. (2013). Emotion and Decision-Making Explained. Oxford University Press.
Salamone, J. D., & Correa, M. (2012). The mysterious motivational functions of mesolimbic dopamine. Neuron, 76(3), 470–485. https://doi.org/10.1016/j.neuron.2012.10.021