Brain
Frontal Lobe
The seat of executive function and personality
Overview
The frontal lobe is the largest of the four cerebral lobes, located at the front of the brain. It is central to executive functions: planning, decision-making, impulse control, and working memory. The motor cortex—part of the frontal lobe—controls voluntary movement. Broca's area, responsible for speech production, also resides here.
Function
- Executive planning and decision-making
- Voluntary motor control via the motor cortex
- Speech production (Broca's area)
- Working memory and attention
- Emotional regulation and personality expression
Key Facts
- The prefrontal cortex is proportionally larger in humans than any other species
- Phineas Gage's accident (1848) revealed the frontal lobe's role in personality
- The frontal lobe is the last brain region to fully mature (~age 25)
- Damage can lead to impulsivity, poor judgment, and personality changes
Key Substructures
- Prefrontal cortex (PFC): executive planning, working memory, and impulse inhibition
- Primary motor cortex (M1, precentral gyrus): voluntary movement execution
- Premotor cortex (PMC): movement planning and sensory-guided movement
- Supplementary motor area (SMA): self-initiated and sequential movements
- Broca's area (left hemisphere, IFG): speech production and language syntax
Clinical Notes
- Damage causes impaired impulse control, poor judgment, and personality changes
- Phineas Gage (1848): iron rod through PFC produced dramatic personality shift
- Broca's aphasia from left frontal lesion: effortful, telegraphic, non-fluent speech
- Motor cortex damage causes contralateral hemiplegia or upper motor neuron weakness