Frontal lobe
Encyclopedia
The frontal lobe is an area in the brain
of humans and other mammal
s, located at the front of each cerebral hemisphere
and positioned anterior to (in front of) the parietal lobe
and superior and anterior to the temporal lobe
s. It is separated from the parietal lobe by a space between tissues called the central sulcus, and from the temporal lobe by a deep fold called the lateral (Sylvian) sulcus. The precentral gyrus, forming the posterior border of the frontal lobe, contains the primary motor cortex
, which controls voluntary movements of specific body parts.
The frontal lobe contains most of the dopamine-sensitive neurons in the cerebral cortex
. The dopamine
system is associated with reward, attention, short-term memory tasks, planning, and motivation. Dopamine tends to limit and select sensory information arriving from the thalamus
to the fore-brain. A report from the National Institute of Mental Health says a gene variant that reduces dopamine activity in the prefrontal cortex
is related to poorer performance and inefficient functioning of that brain region during working memory tasks, and to slightly increased risk for schizophrenia
.
surface of the human brain
, the central sulcus
separates the frontal lobe from the parietal lobe. The lateral sulcus separates the frontal lobe from the temporal lobe
.
The frontal lobe can be divided into a lateral
, polar, orbital (above the orbit
; also called basal or ventral
), and medial
part. Each of these parts consists of particular gyri
:
The gyri are separated by sulci
. E.g., the precentral gyrus is in front of the central sulcus
, and behind the precentral sulcus
. The superior and middle frontal gyri are divided by the superior frontal sulcus
. The middle and inferior frontal gyri are divided by the inferior frontal sulcus
.
In humans, the frontal lobe reaches full maturity around only after the 20s, marking the cognitive maturity associated with adulthood.
Dr. Arthur Toga, a UCLA professor of neurology, found increased myelin
in the frontal lobe white matter of young adults compared to that of teens. A typical onset of schizophrenia in early adult years correlates with poorly myelinated and thus inefficient connections between cells in the fore-brain.
The frontal lobes also play an important part in retaining longer term memories which are not task-based. These are often memories associated with emotions derived from input from the brain's limbic system
. The frontal lobe modifies those emotions to generally fit socially acceptable norms.
Psychological tests that measure frontal lobe function include finger tapping, Wisconsin Card Sorting Task, and measures of verbal and figural fluency.
, first developed by Portuguese
neurologist
Egas Moniz
, involved damaging the pathways connecting the frontal lobe to the limbic system
. Frontal lobotomy
(sometimes called frontal leucotomy) successfully reduced distress but at the cost of often blunting the subject's emotions, volition and personality
. The indiscriminate use of this psychosurgical
procedure, combined with its severe side effects and dangerous nature, gained it a bad reputation. The frontal lobotomy has largely died out as a psychiatric treatment. More precise psychosurgical procedures are still used, although rarely. They may include anterior capsulotomy (bilateral thermal lesions of the anterior limbs of the internal capsule
) or the bilateral cingulotomy
(involving lesions of the anterior cingulate gyri) and might be used to treat otherwise untreatable obsessional disorders
or clinical depression
Stuss (1999) suggests a differentiation into two categories according to homogeneity and heterogeneity of function.
Further theoretical approaches to frontal lobe function include:
It may be highlighted that the theories described above differ in their focus on certain processes/systems or construct-lets. Stuss (1999) remarks that the question of homogeneity (single construct) or heterogeneity (multiple processes/systems) of function “may represent a problem of semantics and/or incomplete functional analysis rather than an unresolvable dichotomy” (p. 348). However, further research will show if a unified theory of frontal lobe function that fully accounts for the diversity of functions will be available.
to determine the volume of the frontal cortex in humans, all extant ape species and several monkey
species, Semendeferi et al. found that the human frontal cortex was not relatively larger than the cortex in the other great ape
s but was relatively larger than the frontal cortex in the lesser ape
s and the monkeys.
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
of humans and other mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s, located at the front of each cerebral hemisphere
Cerebral hemisphere
A cerebral hemisphere is one of the two regions of the eutherian brain that are delineated by the median plane, . The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter called the cerebral cortex that is...
and positioned anterior to (in front of) the parietal lobe
Parietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
and superior and anterior to the temporal lobe
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
s. It is separated from the parietal lobe by a space between tissues called the central sulcus, and from the temporal lobe by a deep fold called the lateral (Sylvian) sulcus. The precentral gyrus, forming the posterior border of the frontal lobe, contains the primary motor cortex
Primary motor cortex
The primary motor cortex is a brain region that in humans is located in the posterior portion of the frontal lobe. Itworks in association with pre-motor areas to plan and execute movements. M1 contains large neurons known as Betz cells, which send long axons down the spinal cord to synapse onto...
, which controls voluntary movements of specific body parts.
The frontal lobe contains most of the dopamine-sensitive neurons in the cerebral cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
. The dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
system is associated with reward, attention, short-term memory tasks, planning, and motivation. Dopamine tends to limit and select sensory information arriving from the thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
to the fore-brain. A report from the National Institute of Mental Health says a gene variant that reduces dopamine activity in the prefrontal cortex
Prefrontal cortex
The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...
is related to poorer performance and inefficient functioning of that brain region during working memory tasks, and to slightly increased risk for schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
.
Anatomy
On the lateralAnatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
surface of the human brain
Human brain
The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...
, the central sulcus
Central sulcus
-External links:* via the Neuroscience Information Framework...
separates the frontal lobe from the parietal lobe. The lateral sulcus separates the frontal lobe from the temporal lobe
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
.
The frontal lobe can be divided into a lateral
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
, polar, orbital (above the orbit
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
; also called basal or ventral
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
), and medial
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
part. Each of these parts consists of particular gyri
Gyrus
A gyrus is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci .-Notable gyri:* Superior frontal gyrus, lat. gyrus frontalis superior* Middle frontal gyrus, lat. gyrus frontalis medius...
:
- Lateral part: Precentral gyrus, lateral part of the superior frontal gyrusSuperior frontal gyrusThe superior frontal gyrus makes up about one-third of the frontal lobe of the human brain. It is bounded laterally by the superior frontal sulcus....
, middle frontal gyrusMiddle frontal gyrusThe middle frontal gyrus makes up about one-third of the frontal lobe of the human brain....
, inferior frontal gyrusInferior frontal gyrusThe inferior frontal gyrus is a gyrus of the frontal lobe . It is labelled gyrus frontalis inferior, its Latin name...
. - Polar part: Transverse frontopolar gyri, frontomarginal gyrus.
- Orbital partOrbitofrontal cortexThe orbitofrontal cortex is a prefrontal cortex region in the frontal lobes in the brain which is involved in the cognitive processing of decision-making...
: Lateral orbital gyrus, anterior orbital gyrus, posterior orbital gyrus, medial orbital gyrus, gyrus rectusGyrus rectusThe portion of the frontal lobe medial to the medial orbital gyrus is named the gyrus rectus , and is continuous with the superior frontal gyrus on the medial surface....
. - Medial part: Medial part of the superior frontal gyrusSuperior frontal gyrusThe superior frontal gyrus makes up about one-third of the frontal lobe of the human brain. It is bounded laterally by the superior frontal sulcus....
, cingulate gyrus.
The gyri are separated by sulci
Sulcus (neuroanatomy)
In neuroanatomy, a sulcus is a depression or fissure in the surface of the brain.It surrounds the gyri, creating the characteristic appearance of the brain in humans and other large mammals....
. E.g., the precentral gyrus is in front of the central sulcus
Central sulcus
-External links:* via the Neuroscience Information Framework...
, and behind the precentral sulcus
Precentral sulcus
The precentral sulcus lies parallel to, and in front of, the central sulcus....
. The superior and middle frontal gyri are divided by the superior frontal sulcus
Superior frontal sulcus
The superior frontal sulcus is a sulcus between the superior frontal gyrus and the middle frontal gyrus....
. The middle and inferior frontal gyri are divided by the inferior frontal sulcus
Inferior frontal sulcus
The inferior frontal sulcus is a sulcus between the middle frontal gyrus and the inferior frontal gyrus....
.
In humans, the frontal lobe reaches full maturity around only after the 20s, marking the cognitive maturity associated with adulthood.
Dr. Arthur Toga, a UCLA professor of neurology, found increased myelin
Myelin
Myelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination...
in the frontal lobe white matter of young adults compared to that of teens. A typical onset of schizophrenia in early adult years correlates with poorly myelinated and thus inefficient connections between cells in the fore-brain.
Function
The executive functions of the frontal lobes involve the ability to recognize future consequences resulting from current actions, to choose between good and bad actions (or better and best), override and suppress unacceptable social responses, and determine similarities and differences between things or events. Therefore, it is involved in higher mental functions.The frontal lobes also play an important part in retaining longer term memories which are not task-based. These are often memories associated with emotions derived from input from the brain's limbic system
Limbic system
The limbic system is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which seemingly support a variety of functions including emotion, behavior, long term memory, and olfaction. The term "limbic" comes from the Latin...
. The frontal lobe modifies those emotions to generally fit socially acceptable norms.
Psychological tests that measure frontal lobe function include finger tapping, Wisconsin Card Sorting Task, and measures of verbal and figural fluency.
Psychosurgery
In the early 20th century, a medical treatment for mental illnessMental illness
A mental disorder or mental illness is a psychological or behavioral pattern generally associated with subjective distress or disability that occurs in an individual, and which is not a part of normal development or culture. Such a disorder may consist of a combination of affective, behavioural,...
, first developed by Portuguese
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
neurologist
Neurologist
A neurologist is a physician who specializes in neurology, and is trained to investigate, or diagnose and treat neurological disorders.Neurology is the medical specialty related to the human nervous system. The nervous system encompasses the brain, spinal cord, and peripheral nerves. A specialist...
Egas Moniz
Egas Moniz
António Caetano de Abreu Freire Egas Moniz , known as Egas Moniz , was a Portuguese neurologist and the developer of cerebral angiography...
, involved damaging the pathways connecting the frontal lobe to the limbic system
Limbic system
The limbic system is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which seemingly support a variety of functions including emotion, behavior, long term memory, and olfaction. The term "limbic" comes from the Latin...
. Frontal lobotomy
Lobotomy
Lobotomy "; τομή – tomē: "cut/slice") is a neurosurgical procedure, a form of psychosurgery, also known as a leukotomy or leucotomy . It consists of cutting the connections to and from the prefrontal cortex, the anterior part of the frontal lobes of the brain...
(sometimes called frontal leucotomy) successfully reduced distress but at the cost of often blunting the subject's emotions, volition and personality
Personality psychology
Personality psychology is a branch of psychology that studies personality and individual differences. Its areas of focus include:* Constructing a coherent picture of the individual and his or her major psychological processes...
. The indiscriminate use of this psychosurgical
Psychosurgery
Psychosurgery, also called neurosurgery for mental disorder , is the neurosurgical treatment of mental disorder. Psychosurgery has always been a controversial medical field. The modern history of psychosurgery begins in the 1880s under the Swiss psychiatrist Gottlieb Burckhardt...
procedure, combined with its severe side effects and dangerous nature, gained it a bad reputation. The frontal lobotomy has largely died out as a psychiatric treatment. More precise psychosurgical procedures are still used, although rarely. They may include anterior capsulotomy (bilateral thermal lesions of the anterior limbs of the internal capsule
Internal capsule
The internal capsule is an area of white matter in the brain that separates the caudate nucleus and the thalamus from the lenticular nucleus. The internal capsule contains both ascending and descending axons....
) or the bilateral cingulotomy
Bilateral cingulotomy
Bilateral cingulotomy is a form of psychosurgery, introduced in 1948 as an alternative to lobotomy. Today, it is mainly used in the treatment of obsessive-compulsive disorder, depression and addiction. It is also, rarely, used in the treatment of chronic pain...
(involving lesions of the anterior cingulate gyri) and might be used to treat otherwise untreatable obsessional disorders
Obsessive-compulsive disorder
Obsessive–compulsive disorder is an anxiety disorder characterized by intrusive thoughts that produce uneasiness, apprehension, fear, or worry, by repetitive behaviors aimed at reducing the associated anxiety, or by a combination of such obsessions and compulsions...
or clinical depression
Clinical depression
Major depressive disorder is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities...
Theories of function
Theories of frontal lobe function can be differentiated into four categories:- Single-process theories. Posit "that damage to a single process or system is responsible for a number of different dysexecutive symptoms” (Burgess, 2003, p. 309).
- Multi-process theories. Propose “that the frontal lobe executive system consists of a number of components that typically work together in everyday actions [(heterogeneity of function)]“ (Burgess, 2003, p. 310).
- Construct-led theories. Assume “that most if not all frontal functions can be explained by one construct (homogeneity of function) such as working memory or inhibition” (Stuss, 1999, p. 348; cf. Burgess & Simons, 2005).
- Single-symptom theories. Suggest that a specific dysexecutive symptom (e.g., confabulation) is related to the processes and construct of the underlying structures (cf. Burgess & Simons, 2005).
Stuss (1999) suggests a differentiation into two categories according to homogeneity and heterogeneity of function.
Further theoretical approaches to frontal lobe function include:
- Grafman's managerial knowledge units (MKU) / structured event complex (SEC) approach (cf. Wood & Grafman, 2003)
- Miller & Cohen's integrative theory of prefrontal functioning (e.g. Miller & Cohen, 2001)
- Rolls's stimulus-reward approach and Stuss's anterior attentional functions (Burgess & Simons, 2005; Burgess, 2003; Burke, 2007).
It may be highlighted that the theories described above differ in their focus on certain processes/systems or construct-lets. Stuss (1999) remarks that the question of homogeneity (single construct) or heterogeneity (multiple processes/systems) of function “may represent a problem of semantics and/or incomplete functional analysis rather than an unresolvable dichotomy” (p. 348). However, further research will show if a unified theory of frontal lobe function that fully accounts for the diversity of functions will be available.
Damage
Damage to the frontal lobes can lead to a variety of results:- Mental flexibility and spontaneity are impaired, but IQ is not reduced.
- Talking may increase or decrease dramatically.
- Perceptions regarding risk-taking and rule-abiding are impaired.
- Socialization can diminish or increase.
- Orbital frontal lobe damage can result in peculiar sexual habits.
- Dorsolateral frontal lobe damage reduces sexual interest.
- Creativity is diminished or increased as well as problem solving skills.
- Distraction occurs more frequently.
- Loss of smell and/or taste.
Evolution
For many years, many scientists thought that the frontal lobe was disproportionately enlarged in humans compared to other primates. They thought that this was an important feature of human evolution and was the primary reason why human cognition is different from that of the other primates. However, this view has been challenged by newer research. Using magnetic resonance imagingMagnetic resonance imaging
Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...
to determine the volume of the frontal cortex in humans, all extant ape species and several monkey
Monkey
A monkey is a primate, either an Old World monkey or a New World monkey. There are about 260 known living species of monkey. Many are arboreal, although there are species that live primarily on the ground, such as baboons. Monkeys are generally considered to be intelligent. Unlike apes, monkeys...
species, Semendeferi et al. found that the human frontal cortex was not relatively larger than the cortex in the other great ape
Hominidae
The Hominidae or include them .), as the term is used here, form a taxonomic family, including four extant genera: chimpanzees , gorillas , humans , and orangutans ....
s but was relatively larger than the frontal cortex in the lesser ape
Gibbon
Gibbons are apes in the family Hylobatidae . The family is divided into four genera based on their diploid chromosome number: Hylobates , Hoolock , Nomascus , and Symphalangus . The extinct Bunopithecus sericus is a gibbon or gibbon-like ape which, until recently, was thought to be closely related...
s and the monkeys.
Additional images
See also
- Brain lobesLobes of the brainBrain lobes were originally a purely anatomical classification, but have been shown also to be related to different brain functions. The telencephalon , the largest portion of the human brain, is divided into lobes, but so is the cerebellum...
- Broca's AreaBroca's areaBroca's area is a region of the hominid brain with functions linked to speech production.The production of language has been linked to the Broca’s area since Pierre Paul Broca reported impairments in two patients. They had lost the ability to speak after injury to the posterior inferior frontal...
- Limen insulaeLimen insulaeThe Limen insulae is the point at which the Insular cortex is continuous with the cortex of the Frontal lobe.-External links:*http://www.uams.edu/radiology/education/residency/diagnostic/pdf/sylvian_cistern_RSNA2003.pdf...
- Regions in the human brain
- Phineas GagePhineas GagePhineas P. Gage was an American railroad construction foreman now remembered for his improbablesurvival of an accident in which a large iron rod was driven completely through his head, destroying much of his brain's left frontal lobe, and for that injury's reported effects on his personality and...
- Railroad worker who survived a metal rod being driven through his forebrain
External links
- NIF Search - Frontal Lobe via the Neuroscience Information FrameworkNeuroscience Information FrameworkThe Neuroscience Information Framework is a repository of global neuroscience web resources, including experimental, clinical, and translational neuroscience databases, knowledge bases, atlases, and genetic/genomic resources.-Description:...