HUMAN BRAIN
(Anatomy)

FRONTAL LOBES

Motor – responsible for making movements

Premotor – selects movements, selection and direction of motor sequences, choose behavior in response to clues, frontal eye fields

Prefrontal (PFC) – controls the cognitive processes so that appropriate movements are selected at the correct time and place

PFC -- Short term memory (internalized record of what just occurred) 3 areas of the PFC

1. Dorsal lateral
• receives input from posterior parietal and superior temporal sulcus,
• extensive connections to cingulate gyrus , basal ganglia, and superior colliculus
• selection of behavior based on short term memory
2. Inferior orbital
• receives inputs from temporal lobes (auditory and visual aspects), somatosensory
• cortex, amygdala, gustatory cortex in insula, and olfactory regions
• projects to amygdala and hypothalamus
• difficulty with context, especially in social situations
• notorious for making social gaffes
• rule breaking

Functions of the PFC (executive control)

• attention span
• perseverance
• planning
• judgment
• impulse control
• organization
• self-monitoring and supervision
• problem solving
• critical thinking
• forward thinking
• learning from experience and mistakes
• ability to feel and express emotions
• influences the limbic system
• empathy
• internal supervision

Problems of the PFC (executive dyscontrol)

• short attention span
• distractibility
• lack of perseverance
• impulse control problems
• hyperactivity
• chronic lateness, poor time management
• poor organization and planning
• procrastination
• unavailability of emotions
• misperceptions
• poor judgement
• trouble learning from experience
• short term memory problems
• social and test anxiety
• lying
• misperceptions

Frontal lobe injury – problems with:

• Planning         
• Time
• Persistence
• Diligence
• Inhibiting behavior
• Controlled by external clues
• Distracted easily

The prefrontal cortex (pfc) is the most evolved part of the brain.  It occupies the front third of the brain, underneath the forehead.  It is often divided into three sections: the dorsal lateral section (on the outside surface of the pfc), the inferior orbital section (on the front undersurface of the brain) and the cingulate gyrus (which runs through the middle of the frontal lobes).  The cingulate gyrus, often considered as part of the limbic system, will be covered in its own chapter.  The dorsal lateral and inferior orbital gyrus are often termed the executive control center of the brain and will be discussed together in this chapter.  When necessary, I’ll distinguish what is known about their function. 

Overall, the pfc is the part of the brain that watches, supervises, guides, directs and focuses your behavior.  It contains “executive functions,” such as time management, judgment, impulse control, planning, organization and critical thinking.  Our ability as a species to think, plan ahead, use time wisely and communicate with others is heavily influenced by this part of the brain.  The pfc is responsible for behaviors that are necessary for you to be appropriate, goal directed, socially responsible and effective. 

North Carolina neuropsychiatrist Thomas Gualtieri, MD succinctly summarized the human functions of the pfc, “…the capacity to formulate goals, to make plans for their execution, to carry them out in an effective way, and to change course and improvise in the face of obstacles or failure, and to do so successfully, in the absence of external direction or structure.  The capacity of the individual to generate goals and to achieve them is considered to be an essential aspect of a mature and effective personality.  It is not a social convention or an artifact of culture.  It is hard wired in the construction of the prefrontal cortex and its connections.” (In The Neuropsychiatry of Personality Disorders, 1996, Edited by John Ratey. MD.)

The pfc helps you think about what you say or do before you say or do it (especially the inferior orbital pfc).  The pfc helps you, in accordance with your experience, select actions between alternatives in social and work situations.  For example, if you are having a disagreement with your spouse and you have good pfc function you are more likely to give a thoughtful response that helps the situation.  If you have poor pfc function you are more likely to do or say something that will make the situation worse.  Likewise, if you’re a check out clerk in a grocery store and a difficult, complaining person comes through your line (who has poor pfc function) and you have good pfc function you are more likely to keep quiet or give a thoughtful response that helps the situation.  If you have poor pfc function you are more likely to do or say something that will inflame the situation.  The pfc helps you problem solve, see ahead of a situation and, through experience, pick between the most helpful alternatives.  Effectively playing a game such as chess requires good pfc function.

This is also the part of the brain that helps you learn from mistakes.  Good pfc function doesn’t that mean you won’t make mistakes.  Rather, it generally means you won’t make the same mistake over and over.  You are able to learn from the past and apply its lessons.  For example, a student with good pfc function is likely to learn that if he or she starts a long term project early, there is more time for research and less anxiety over getting it done.  A student with decreased pfc function doesn’t learn from past frustrations and may tend to put everything off until the last minute.  Poor pfc function tends to be involved in people who have trouble learning from experience.  They tend to make repetitive mistakes.  Their actions are not based on experience, but rather on the moment, and immediate wants and needs.   

The pfc is also involved with sustaining attention span (especially the dorsal lateral pfc).  It helps you focus on important information while filtering out less significant thoughts and sensations.  Attention span is required for short term memory and learning.  The pfc, through its many connections within the brain, helps you keep on task and allows you to stay with a project until it is finished.  The pfc actually sends quieting signals to the limbic and sensory parts of the brain.  When there is a need to focus, the pfc decreases the distracting input from other brain areas.  It helps to inhibit or filter out distractions.  When the pfc is underactive there is less of a filtering mechanism available and distractibility becomes common (this will be discussed in detail under attention deficit disorder).

The pfc is also the part of the brain that allows you to feel and express emotions; to feel happiness, sadness, joy, and love (especially the dorsal lateral pfc).  It is different from the limbic system, which is a more primitive part of the brain.  Even though the limbic system controls mood and libido, the prefrontal cortex is able to translate the feelings of the limbic system into recognizable feelings, emotions and words, such as love, passion or hate.  Underactivity or damage in this part of the brain often leads to a decreased ability to express thoughts and feelings.

Thoughtfulness and impulse control is heavily influenced by the pfc. The ability to think through the consequences of behavior is essential to effective living, in nearly every aspect of human life.  Common examples of the need for forethought include: choosing a good mate, interacting with customers, dealing with difficult children, spending money and driving on the freeway.  Without proper function in this part of the brain it is difficult to act in consistent thoughtful ways and impulses can take over. 

The pfc has many connections to the limbic system.  It sends inhibitory messages that help keep it under control.  It helps you “use your head along with your emotions.”  When there is damage or underactivity in this part of the brain, especially on the left side,  the pfc cannot appropriately inhibit the limbic system, causing an increased vulnerability to depression if the limbic system becomes overactive.  A classic example of this problem occurs in people who have had left frontal lobe strokes.  Sixty percent of patients with these strokes develop a major depression within a year.