You are exactly right about the frontal lobe of the brain having the most influence on both our personalities and behaviors. It is the seat of our emotions and our personality traits. According to the Centre for Neuro Skills,
[t]he frontal lobes are involved in motor function, problem solving, spontaneity, memory, language, initiation, judgement, impulse control, and social and sexual behavior.
This is why an injury to the frontal lobe can cause such a wide variety of symptoms in people.
Because of their location, at the front of the cranium, and their large size, the frontal lobes are especially susceptible to damage through falls, in particular. Of course this is why protective helmets are required for any sports or activities in which a traumatic brain injury could occur. This includes everything from bicycle riding to football.
The two halves of the frontal lobe are asymmetrical, and each side controls some specific things. The left frontal lobe primarily controls all language-related movement, and the right frontal lobe is concerned with non-verbal skills and abilities. Because the science is not exact and because this division is not strictly true for all people, the results of any frontal lobe damage can vary from person to person.
Once a frontal lobe has been traumatically injured, one or more dramatic changes might occur. These are generalities, remember, and may not apply to every patient suffering a frontal lobe trauma.
- Motor function: this usually shows itself in the loss of arm, hand, and finger strength. Fine motor movements and complex series of motor movements may also be impaired. Often patients will have trouble showing "spontaneous facial expression" or have some difficulty speaking.
- Spatial orientation: a person who has suffered a traumatic brain injury often loses his connectedness to his surroundings. For example, he misjudges how much space he is leaving between himself and the person to who he is talking or how close he is to a chair when he tries to sit down in it.
- Intelligence: while IQ does not seem to be significantly impacted, problem-solving skills and memory do seem to be affected.
- Social skills: one significant result of a traumatic brain injury is the patient's inability to interpret feedback from his environment. This shows itself in rule-breaking and excessive or protracted responses to questions. The injured person is unable to accurately reed the social signals that most of us have no trouble reading. For example, we can sense when our listeners are bored with our stories or when someone is asking a question our of politeness rather than a sincere desire to start a deep conversation.
- Sexual behaviors: depending on where the damage occurred, the patient may act sexually in abnormal ways or he may lose interest in sexual activity altogether. Obviously everything in between these two extremes is possible.
Both physical changes and changes in social behaviors are hallmarks of damage to frontal lobe damage. Knowing good from bad or understanding the consequences of any given action are likely to be impaired by such an injury, as well. According to the Brain Injury Institute,
The frontal lobe controls motor skills like hand/eye coordination, conscious thought, emotions, and even your personality. As a result of a brain injury, frontal lobe damage may impair your attention span, motivation, judgment, and organizational capacity.
These are compelling reasons to wear a helmet to alleviate the risk of such an injury.