The left frontal lobe is the front portion of the left cerebrum in the brain, and it controls emotion and personality. The human brain is divided into two distinct hemispheres; the frontal lobe is the first half of the brain, located in front of the parietal temporal lobes. Frontal lobe damage can change facial expressions and cause loss of fine motor control. The left side of this portion is responsible for language skills, problem solving ability, impulse control, and judgment.
The exact roles of the right and left frontal lobe change from person to person, but they tend to have the same functions. This portion is the most commonly injured area of the brain, so researchers have been able to determine what certain parts of it do. Damage of a section of the brain called Broca's area, for example, causes aphasia, or the inability to speak. Other injuries affect personality, cause depression, and result in the loss of problem solving skills.
The most famous case of an injury to this part of the brain occurred in 1848 to a man named Phineas Gage, a railroad construction foreman. One day, Gage was carrying around a tamping iron, a rod used to pack down dynamite, while working. He went to use the rod to tamp dynamite, and it exploded unexpectedly in his face. This sent the rod directly through his skull and into his left frontal lobe, straight through the top of his head, and throwing the rod far down the tracks.
Much information is known about Gage's case because it was the first recorded experience someone had survived such a severe head injury. The case is also notable because despite the massive damage to his brain, Gage was able to survive almost normally until age 36. After his accident, Gage's personality changed significantly. He become lewd and irritable, unable to hold down his former job. Prior to his accident, Gage was quiet, reserved, and a hard worker.
The left frontal lobe was one of the area's removed by lobotomies in the early 20th century. Damage to the area causes an individual to have trouble completing simple tasks formerly done with great ease. Smell and taste may also be harmed because this area has connections to the olfactory system. Individuals become distracted easily and have a hard time judging the consequences of their actions.