The front of the brain is called the frontal lobe. It’s the largest of the brain’s four lobes, sitting behind your forehead and stretching back to a groove called the central sulcus, which separates it from the parietal lobe behind it. A second groove along the side of the brain, the lateral sulcus, marks its border with the temporal lobe below. The frontal lobe handles an enormous range of tasks, from planning your day to controlling your muscles to producing speech.
What the Frontal Lobe Does
The frontal lobe manages what neuroscientists call executive function, which is essentially your brain’s command center for thinking and behaving in organized, goal-directed ways. Executive function breaks down into three core abilities: working memory, cognitive flexibility, and inhibition control.
Working memory is what lets you hold information in mind long enough to use it, like keeping a phone number in your head while you walk across the room to write it down. Cognitive flexibility is your ability to shift gears smoothly between tasks or adapt when circumstances change. Inhibition control governs how well you manage your impulses, emotions, and focus. Together, these three abilities underpin nearly everything people think of as higher-level thinking: reasoning, planning, organizing, problem-solving, and making decisions.
The Prefrontal Cortex
The very front portion of the frontal lobe, the area closest to your forehead, is called the prefrontal cortex. This region is especially important for complex thought and personality. Within it, different subregions handle different jobs. One well-studied area, the dorsolateral prefrontal cortex, plays a central role in working memory, abstract reasoning, planning, and the ability to suppress unhelpful responses. Other subregions deeper and lower in the prefrontal cortex are more involved in emotional processing, reward evaluation, and social decision-making.
The prefrontal cortex is one of the last brain regions to fully mature. According to the National Institute of Mental Health, the brain doesn’t finish developing until the mid-to-late 20s, and the prefrontal cortex is among the final areas to reach maturity. This is a big part of why teenagers and young adults tend to be more impulsive and more prone to risky decisions than older adults, even when they intellectually understand the consequences.
Movement and the Motor Cortex
Not all of the frontal lobe is about thinking. A strip of brain tissue at the very back of the frontal lobe, just in front of the central sulcus, is the primary motor cortex. This region controls voluntary movement. It doesn’t typically fire individual muscles one at a time. Instead, it coordinates sequences of movements that require multiple muscle groups working together, like reaching for a cup or kicking a ball.
The motor cortex is organized like a map of the body. Regions near the top of the brain control the legs and feet, while regions along the side control the hands, face, and tongue. The areas devoted to the hands and mouth are disproportionately large compared to, say, the trunk, which reflects how much fine motor control those body parts require.
Speech Production and Broca’s Area
In most people, the left frontal lobe contains a region called Broca’s area, which is critical for producing speech. This area controls the ability to articulate ideas, form words, and use language accurately in both spoken and written form. Damage to Broca’s area typically leaves a person able to understand what others say but struggling to produce fluent speech themselves. Words come out slowly, effortfully, and often in short fragments, even though the person knows exactly what they want to say.
What Happens When the Frontal Lobe Is Damaged
Because the frontal lobe handles so many different functions, damage to it can look very different depending on exactly where the injury occurs. Some of the most common effects include personality changes, difficulty controlling impulses (including what you say or do), trouble with reasoning and planning, problems switching attention between tasks, certain types of memory loss, and difficulty controlling muscles used for movement or speech.
Personality changes are often the most striking symptom to the people around someone with frontal lobe damage. A person who was cautious and polite might become impulsive and socially inappropriate, not because they’ve changed who they “are” in some deep sense, but because the brain region responsible for filtering behavior is no longer functioning properly. These changes can result from traumatic brain injury, stroke, tumors, or degenerative diseases that affect the frontal lobe.
How the Human Frontal Lobe Compares to Other Species
There’s a popular idea that humans have unusually large frontal lobes compared to other animals, and that this explains our advanced cognitive abilities. The reality is more nuanced. A large-scale analysis published in the Proceedings of the National Academy of Sciences found that the human frontal lobe is roughly the size you’d predict for a primate brain of our overall volume. In other words, our frontal lobes aren’t disproportionately large. They’re big because our whole brain is big. Several non-human primates actually have frontal lobes that make up a larger percentage of their total brain volume than ours do.
What does seem to set the human brain apart is not sheer frontal lobe size but the complexity of the connections within and between brain regions. The density of wiring, and the way different areas of the frontal lobe communicate with the rest of the brain, likely matters more than volume alone.