Humans have big brains and our frontal lobes, just behind the forehead, are particularly huge. The frontal lobes, the largest of the four, are in many ways the lobe which participates most in making us human (It is one of the lobes of the neocortex).
- The frontal lobes are important for voluntary movement, expressive language and for managing higher level executive functions.
- Executive functions refer to a collection of cognitive skills including the capacity to plan, organise, initiate, self-monitor and control one’s responses in order to achieve a goal. eg You rely on your frontal lobes when you do things like make plans, switch from one activity to another, or resist temptation.
- The frontal lobes are considered our behaviour and emotional control centre and home to our personality.
The frontal lobe is the largest lobe accounting for 41% of the total neocortical volume.
- The frontal lobe resides largely in the anterior cranial fossa, lying on the orbital plate of the frontal bone.
- Its most anterior part is known as the frontal pole and extends posteriorly to the central sulcus which separates it from the parietal lobe.
- Posteroinferiorly it is separated from the temporal lobe by the lateral sulcus..
- Generally, the further forward in the frontal lobe you go, the more high level the function, and the more connections to tell the rest of the brain and body what to do.
- Middle cerebral artery (MCA): lateral frontal lobe
- Anterior cerebral artery (ACA): medial frontal lobe
For many years, many scientists thought that the frontal lobe was comparatively larger in humans than in other primates. They thought that this was an important feature of human evolution and was the main reason why human cognition is different from that of the other primates.
- This view has been challenged by research. Magnetic resonance imaging was used to find the volume of the frontal cortex in humans, all living ape species and several monkey species. The human frontal cortex is not relatively larger than the cortex in the other great apes, but it is relatively larger than the frontal cortex in the lesser apes and the monkeys.
However, what sets us apart from other mammals is not so much brain size but reorganization of our brains in terms of connectivity and neurotransmitter changes. These changes may be summarized in the following manner.
- Progressive increase in size.
- Hemispheric asymmetry (ie the structural or morphological differences between the right and left hemispheres, as well as the differences in the information processing capacity between the hemispheres)
- Neuropil (ie unmyelinated axons, dendrites and glial cell processes that forms a synaptically dense region) reorganization.
- Reorganization in terms of neurotransmitter systems.
- Receptor modification
Brain size: The so-called “missing link” hominid, Australopithecus africanus (brain volume approximately 450 mL), 3 million years later Neanderthals approx. 1500 mL and subsequently a slight decrease again in modern humans Homo sapiens sapiens to 1350 mL.
The frontal lobes are considered our emotional control center and home to our personality. There is no other part of the brain where lesions can cause such a wide variety of symptoms.
The frontal lobes are extremely vulnerable to injury due to their location at the front of the cranium, proximity to the sphenoid wing and their large size. Image: Lesser wing of sphenoid bone (green). Other parts of sphenoid are colored in red.
MRI studies have shown that the frontal area is the most common region of injury following mild to moderate traumatic brain injury
- Disturbance of motor function is typically characterized by loss of fine movements and strength of the arms, hands and fingers. Complex chains of motor movement also seem to be controlled by the frontal lobes. Patients with frontal lobe damage exhibit little spontaneous facial expression, which points to the role of the frontal lobes in facial expression. Broca's Aphasia, or difficulty in speaking, has been associated with frontal damage.
- Frontal lobe damage seems to have an impact on divergent thinking, or flexibility and problem solving ability. There is also evidence showing lingering interference with attention and memory even after good recovery from a TBI
- One of the most common effects of frontal damage can be a dramatic change in social behavior. A person's personality can undergo significant changes after an injury to the frontal lobes, especially when both lobes are involved.
- Sexual behavior can also be effected by frontal lesions.
The frontal lobe collects some information from the body and environment. It also gathers information from all other parts of the brain.It then sorts out what that information means; and organises a response.
The frontal lobe manages most of what the brain does. It keeps us from doing really silly things and is responsible for the charming personality you have!
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