Editing Frontal lobe

{{short description|Part of the brain}}
{{distinguish | Prefrontal cortex}}
{{Infobox brain
| Name            = Frontal lobe
| Latin           = lobus frontalis
| Image           = {{Cerebrum labelled map|Frontal lobe|Inline=1}}
| Caption         = Principal fissures and lobes of the [[cerebrum]] viewed laterally (Frontal lobe is shown in blue.).
| Image2          = Gray729.png
| IsPartOf        = [[Cerebrum]]
| Artery          = [[Anterior cerebral artery|Anterior cerebral]] <br/> [[Middle cerebral artery|Middle cerebral]]
| Vein            =
| Acronym         = FL
|System=|Function=|Location=}}

The '''frontal lobe''' is the largest of the four major [[lobes of the brain]] in [[mammal]]s, and is located at the front of each [[cerebral hemisphere]] (in front of the [[parietal lobe]] and the [[temporal lobe]]). It is parted from the parietal lobe by a [[Sulcus (neuroanatomy)|groove]] between tissues called the [[central sulcus]] and from the temporal lobe by a deeper groove called the [[lateral sulcus]] (Sylvian fissure). The most anterior rounded part of the frontal lobe (though not well-defined) is known as the frontal pole, one of the three [[Cerebral hemisphere#Poles|poles of the cerebrum]].<ref name="radiopaedia">{{cite web|last1=Muzio|first1=Bruno Di|title=Frontal pole {{!}} Radiology Reference Article {{!}} Radiopaedia.org|url=https://radiopaedia.org/articles/frontal-pole|website=radiopaedia.org|language=en}}</ref>

The frontal lobe is covered by the '''frontal cortex'''.<ref>{{Citation |last1=João |first1=Rafael Batista |title=Frontal Lobe: Functional Neuroanatomy of Its Circuitry and Related Disconnection Syndromes |date=2018-10-03 |url=http://www.intechopen.com/books/prefrontal-cortex/frontal-lobe-functional-neuroanatomy-of-its-circuitry-and-related-disconnection-syndromes |work=Prefrontal Cortex |editor-last=Starcevic |editor-first=Ana |access-date=2023-06-24 |publisher=InTech |language=en |doi=10.5772/intechopen.79571 |isbn=978-1-78923-903-4 |last2=Filgueiras |first2=Raquel Mattos |s2cid=149544570 |editor2-last=Filipovic |editor2-first=Branislav|doi-access=free |url-access=subscription }}</ref> The frontal cortex includes the [[premotor cortex]] and the [[primary motor cortex]] – parts of the [[motor cortex]]. The front part of the frontal cortex is covered by the [[prefrontal cortex]]. The [[nonprimary motor cortex]] is a functionally defined portion of the frontal lobe.

There are four principal [[Gyrus|gyri]] in the frontal lobe. The [[precentral gyrus]] is directly anterior to the [[central sulcus]], running parallel to it and contains the primary motor cortex, which controls voluntary movements of specific body parts. Three horizontally arranged subsections of the [[frontal gyrus]] are the [[superior frontal gyrus]], the  [[middle frontal gyrus]], and the [[inferior frontal gyrus]]. The inferior frontal gyrus is divided into three parts – the [[Orbital part of inferior frontal gyrus|orbital part]], the [[Brodmann area 44|triangular part]] and the [[Opercular part of inferior frontal gyrus|opercular part]].<ref name="Carpenter">{{cite book |last1=Carpenter |first1=Malcolm |title=Core text of neuroanatomy |date=1985 |publisher=Williams & Wilkins |isbn=978-0683014556 |pages=22–23 |edition=3rd}}</ref>

The frontal lobe contains most of the [[Dopaminergic pathways|dopaminergic neurons]] in the [[cerebral cortex]]. The [[dopaminergic pathways]] are associated with [[Reward system|reward]], [[attention]], [[short-term memory]] tasks, [[planning]], and [[motivation]]. [[Dopamine]] tends to limit and select [[sense|sensory information]] coming from the [[thalamus]] to the [[forebrain]].<ref>{{Cite web |title=Incoming Sensory Information - an overview {{!}} ScienceDirect Topics |url=https://www.sciencedirect.com/topics/psychology/incoming-sensory-information |access-date=2023-03-31 |website=www.sciencedirect.com}}</ref>

== Structure ==
[[File:Frontal lobe animation.gif|200px|thumb|right|Frontal lobe (red) of left cerebral hemisphere]]
The frontal lobe is the largest lobe of the brain and makes up about a third of the surface area of each hemisphere.<ref name="Carpenter"/> On the [[Anatomical terms of location|lateral]] surface of each hemisphere, 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 (anatomy)|orbit]]; also called basal or [[Anatomical terms of location|ventral]]), and [[Anatomical terms of location|medial]] part. Each of these parts consists of a particular [[gyrus]]:
* Lateral part: lateral part of the [[superior frontal gyrus]], [[middle frontal gyrus]], and [[inferior frontal gyrus]]
* Polar part: [[frontopolar cortex]], transverse frontopolar gyri, frontomarginal gyrus.
* [[Orbitofrontal cortex|Orbital part]]: [[Orbital gyri|Lateral orbital gyrus]], [[orbital gyri|anterior orbital gyrus]], [[posterior orbital gyrus]], [[medial orbital gyrus]], and [[gyrus rectus]]
* Medial part: Medial part of the [[superior frontal gyrus]], [[cingulate gyrus]].

The gyri are separated by [[Sulcus (neuroanatomy)|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 only after the 20s—the prefrontal cortex, in particular, continues in maturing 'til the second and third decades of life<ref>{{Cite journal |last1=Kolk |first1=Sharon M. |last2=Rakic |first2=Pasko |date=January 2022 |title=Development of prefrontal cortex |journal=Neuropsychopharmacology |language=en |volume=47 |issue=1 |pages=41–57 |doi=10.1038/s41386-021-01137-9 |issn=1740-634X |pmc=8511863 |pmid=34645980}}</ref>—which, thereafter, marks the cognitive maturity associated with adulthood. A small amount of [[atrophy]], however, is normal in the aging person's frontal lobe. Fjell, in 2009, studied atrophy of the brain in people aged 60–91 years. The 142 healthy participants were scanned using [[magnetic resonance imaging|MRI]]. Their results were compared to those of 122 participants with [[Alzheimer's disease]]. A [[clinical trial|follow-up]] one year later showed there to have been a marked volumetric decline in those with Alzheimer's and a much smaller decline (averaging 0.5%) in the healthy group.<ref>{{cite journal | vauthors = Fjell AM, Walhovd KB, Fennema-Notestine C, McEvoy LK, Hagler DJ, Holland D, Brewer JB, Dale AM | title = One-year brain atrophy evident in healthy aging | journal = The Journal of Neuroscience | volume = 29 | issue = 48 | pages = 15223–31 | date = December 2009 | pmid = 19955375 | pmc = 2827793 | doi = 10.1523/JNEUROSCI.3252-09.2009 }}</ref>  These findings corroborate those of Coffey, who in 1992 indicated that the frontal lobe decreases in volume approximately 0.5–1% per year.<ref>{{cite journal | vauthors = Coffey CE, Wilkinson WE, Parashos IA, Soady SA, Sullivan RJ, Patterson LJ, Figiel GS, Webb MC, Spritzer CE, Djang WT | title = Quantitative cerebral anatomy of the aging human brain: a cross-sectional study using magnetic resonance imaging | journal = Neurology | volume = 42 | issue = 3 Pt 1 | pages = 527–36 | date = March 1992 | pmid = 1549213 | doi = 10.1212/wnl.42.3.527 | s2cid = 20481757 }}</ref>

== Function ==
The entirety of the frontal cortex can be considered the "action cortex", much as the [[posterior cortical hot zone|posterior cortex]] is considered the "sensory cortex". It is devoted to action of one kind or another: skeletal movement, ocular movement, speech control, and the expression of emotions. In humans, the largest part of the frontal cortex, the [[prefrontal cortex]] (PFC), is responsible for internal, purposeful mental action, commonly called reasoning or [[prefrontal synthesis]].

The function of the PFC involves the ability to project future consequences that result from current actions. PFC functions also include override and suppression of socially unacceptable responses as well as differentiation of tasks.

The PFC also plays an important part in integrating longer non-task based memories stored across the brain. These are often memories associated with emotions derived from input from the brain's [[limbic system]]. The frontal lobe modifies those emotions, generally to fit socially acceptable norms.{{citation needed |date=July 2024}}

[[Psychological testing|Psychological tests]] that measure frontal lobe function include [[Tapping rate|finger tapping]] (as the frontal lobe controls voluntary movement), the [[Wisconsin Card Sorting Test]], and measures of [[language]], [[numeracy|numeracy skills]],<ref>{{cite journal | vauthors = Kimberg DY, Farah MJ | title = A unified account of cognitive impairments following frontal lobe damage: the role of working memory in complex, organized behavior | journal = Journal of Experimental Psychology. General | volume = 122 | issue = 4 | pages = 411–28 | date = December 1993 | pmid = 8263463 | doi = 10.1037/0096-3445.122.4.411 | url = http://content.apa.org/journals/xge/122/4/411 | url-access = subscription }}</ref> and decision making,<ref>{{cite journal | vauthors = Yang X, Gao M, Shi J, Ye H, Chen S | title = Modulating the Activity of the DLPFC and OFC Has Distinct Effects on Risk and Ambiguity Decision-Making: A tDCS Study | journal = Frontiers in Psychology | volume = 8 | pages = 1417 | date = 2017 | pmid = 28878714 | pmc = 5572270 | doi = 10.3389/fpsyg.2017.01417 | doi-access = free }}</ref> all of which are controlled by the frontal lobe.

==Clinical significance==
{{main|Frontal lobe disorder}}
{{main|Frontal lobe injury}}

===Damage===
Damage to the frontal lobe can occur in a number of ways and result in many different consequences. [[Transient ischemic attacks]] (TIAs) also known as mini-strokes, and [[stroke]]s are common causes of frontal lobe damage in older adults (65 and over). These strokes and mini-strokes can occur due to the blockage of [[Hemodynamics|blood flow]] to the brain or as a result of the rupturing of an [[intracranial aneurysm|aneurysm]] in a [[cerebral artery]]. Other ways in which injury can occur include [[traumatic brain injury|traumatic brain injuries]] incurred following accidents, diagnoses such as [[Alzheimer's disease]] or [[Parkinson's disease]] (which cause [[dementia]] symptoms), and [[frontal lobe epilepsy]] (which can occur at any age).<ref name="Stuss">{{cite journal | vauthors = Stuss DT, Gow CA, Hetherington CR | title = "No longer Gage": frontal lobe dysfunction and emotional changes | journal = Journal of Consulting and Clinical Psychology | volume = 60 | issue = 3 | pages = 349–59 | date = June 1992 | pmid = 1619089 | doi = 10.1037/0022-006X.60.3.349 }}</ref> Very often, frontal lobe damage is recognized in those with [[Fetal Alcohol Spectrum Disorder|prenatal alcohol exposure]].

====Symptoms====
Common effects of damage to the frontal lobe are varied. Patients who have experienced frontal lobe trauma may know the appropriate response to a situation but display inappropriate responses to those same situations in real life {{citation needed|date=May 2025}}. Similarly, emotions that are felt may not be expressed in the face or voice. For example, someone who is feeling happy would not smile, and the voice would be devoid of emotion. Along the same lines, though, the person may also exhibit excessive, unwarranted displays of emotion. Depression is common in stroke patients. Also common is a loss of or decrease in motivation. Someone might not want to carry out normal daily activities and would not feel "up to it".<ref name="Stuss" /> Those who are close to the person who has experienced the damage may notice changes in behavior.<ref>{{cite journal | vauthors = Rowe AD, Bullock PR, Polkey CE, Morris RG | title = "Theory of mind" impairments and their relationship to executive functioning following frontal lobe excisions | journal = Brain | volume = 124 | issue = Pt 3 | pages = 600–16 | date = March 2001 | pmid = 11222459 | doi = 10.1093/brain/124.3.600 | doi-access = free }}</ref> The case of [[Phineas Gage]] was long considered exemplary of these symptoms, though more [[Phineas Gage#Theoretical misuse|recent research]] has suggested that accounts of his personality change have been poorly evidenced. The frontal lobe is the same part of the brain that is responsible for [[executive functions]] such as planning for the future, judgment, decision-making skills, [[attention span]], and inhibition. These functions can decrease in someone whose frontal lobe is damaged.<ref name="Stuss" />

Consequences that are seen less frequently are also varied. [[Confabulation]] may be the most frequently indicated "less common" effect. In the case of confabulation, someone gives false information while maintaining the belief that it is the truth. In a small number of patients, uncharacteristic cheerfulness can be noted. This effect is seen mostly in patients with lesions to the right frontal portion of the brain.<ref name="Stuss" /><ref>{{cite journal | vauthors = Robinson RG, Kubos KL, Starr LB, Rao K, Price TR | title = Mood disorders in stroke patients. Importance of location of lesion | journal = Brain | volume = 107 ( Pt 1) | issue = 1 | pages = 81–93 | date = March 1984 | pmid = 6697163 | doi = 10.1093/brain/107.1.81 }}</ref>

Another infrequent effect is that of [[reduplicative paramnesia]], in which patients believe that the location in which they currently reside is a replica of one located somewhere else. Similarly, those who experience [[Capgras syndrome]] after frontal lobe damage believe that an identical "replacement" has taken the identity of a close friend, relative, or other person and is posing as that person. This last effect is seen mostly in schizophrenic patients who also have a neurological disorder in the frontal lobe.<ref name="Stuss" /><ref>{{cite journal | vauthors = Durani SK, Ford R, Sajjad SH |date=September 1991 |title=Capgras syndrome associated with a frontal lobe tumour |journal=Irish Journal of Psychological Medicine |volume=8 |issue=2 |pages=135–6 |doi=10.1017/S0790966700015093|s2cid=74081936 }}</ref>

====DNA damage====

In the human frontal cortex, a set of genes undergo reduced expression after age 40 and especially after age 70.<ref name="pmid15190254">{{cite journal | vauthors = Lu T, Pan Y, Kao SY, Li C, Kohane I, Chan J, Yankner BA | title = Gene regulation and DNA damage in the ageing human brain | journal = Nature | volume = 429 | issue = 6994 | pages = 883–91 | date = June 2004 | pmid = 15190254 | doi = 10.1038/nature02661 | bibcode = 2004Natur.429..883L | s2cid = 1867993 }}</ref>  This set includes genes that have key functions in [[synaptic plasticity]] important in learning and memory, [[vesicular transport]] and [[mitochondrion|mitochondrial function]].  During [[ageing|aging]], [[DNA damage (naturally occurring)|DNA damage]] is markedly increased in the [[promoter (genetics)|promoters]] of the genes displaying reduced expression in the frontal cortex.  In cultured human neurons, these promoters are selectively damaged by oxidative stress.<ref name="pmid15190254" />

Individuals with [[HIV]] associated neurocognitive disorders accumulate nuclear and [[mitochondrial DNA]] damage in the frontal cortex.<ref name="pmid22554480">{{cite journal | vauthors = Zhang Y, Wang M, Li H, Zhang H, Shi Y, Wei F, Liu D, Liu K, Chen D | title = Accumulation of nuclear and mitochondrial DNA damage in the frontal cortex cells of patients with HIV-associated neurocognitive disorders | journal = Brain Research | volume = 1458 | pages = 1–11 | date = June 2012 | pmid = 22554480 | doi = 10.1016/j.brainres.2012.04.001 | s2cid = 23744888 }}</ref>

===Genetic===
A report from the [[National Institute of Mental Health]] says a [[gene]] variant of [[Catechol-O-methyltransferase|(COMT)]] 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 a slightly increased risk for [[schizophrenia]].<ref>{{cite web | url=http://www.nih.gov/news/pr/may2001/nimh-29.htm | title=Gene Slows Frontal Lobes, Boosts Schizophrenia Risk | publisher=National Institute of Mental Health | date=May 29, 2001 | access-date=2013-06-20|archive-url=https://web.archive.org/web/20150404205032/http://www.nih.gov/news/pr/may2001/nimh-29.htm|archive-date=2015-04-04|url-status=dead}}</ref>

==History==

=== Psychosurgery ===
In the early 20th century, a medical treatment for [[mental illness]], first developed by [[Portugal|Portuguese]] [[neurologist]] [[Egas Moniz]], involved damaging the pathways connecting the frontal lobe to the [[limbic system]]. A frontal [[lobotomy]] (sometimes called frontal leucotomy) successfully reduced distress but at the cost of often blunting the subject's emotions, volition and [[personality psychology|personality]]. The indiscriminate use of this [[psychosurgery|psychosurgical]] procedure, combined with its severe side effects and a [[mortality rate]] of 7.4 to 17 per cent,<ref>{{cite journal | vauthors = Ogren K, Sandlund M | title = Lobotomy at a state mental hospital in Sweden. A survey of patients operated on during the period 1947–1958 | journal = Nordic Journal of Psychiatry | volume = 61 | issue = 5 | pages = 355–62 | year = 2007 | pmid = 17990197 | doi = 10.1080/08039480701643498 | s2cid = 26307989 }}</ref> earned 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 gyrus|cingulate gyri]]) and might be used to treat otherwise untreatable [[obsessive-compulsive disorder|obsessional disorders]] or [[clinical depression]].

=== Theories of function ===
Theories of frontal lobe function can be separated into four categories:
* Single-process theories, which propose that "damage to a single process or system is responsible for a number of different [[Dysexecutive syndrome|dysexecutive symptoms]]"<ref>(Burgess, 2003, p.&nbsp;309).</ref>
* Multi-process theories, which propose "that the frontal lobe executive system consists of a number of components that typically work together in everyday actions (heterogeneity of function)"<ref>(Burgess, 2003, p.&nbsp;310).</ref>
* Construct-led theories, which propose that "most if not all frontal functions can be explained by one construct (homogeneity of function) such as working memory or inhibition"<ref>(Stuss, 1999, p.&nbsp;348; cf. Burgess & Simons, 2005).</ref>
* Single-symptom theories, which propose that a specific dysexecutive symptom (e.g., confabulation) is related to the processes and construct of the underlying structures.<ref>(cf. Burgess & Simons, 2005).</ref>

Other theories include:
* Stuss (1999) suggests a differentiation into two categories according to homogeneity and heterogeneity of function.
* 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.{{Clarify|date=July 2024}} 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.&nbsp;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.

==Other primates==
Many scientists had thought that the frontal lobe was disproportionately enlarged in humans compared to other primates. This was thought to be an important feature of human evolution and seen as the primary reason why human cognition differs from that of other primates. However, this view in relation to great apes has since been challenged by [[neuroimaging]] studies. Using [[magnetic resonance imaging]] to determine the volume of the frontal cortex in humans, all extant ape species, and several [[monkey]] species, it was found that the human frontal cortex was not relatively larger than the cortex of other [[Hominidae|great ape]]s, but was relatively larger than the frontal cortex of [[Gibbon|lesser ape]]s and the monkeys.<ref name="Semendeferi">{{cite journal | vauthors = Semendeferi K, Lu A, Schenker N, Damasio H | title = Humans and great apes share a large frontal cortex | journal = Nature Neuroscience | volume = 5 | issue = 3 | pages = 272–6 | date = March 2002 | pmid = 11850633 | doi = 10.1038/nn814 | s2cid = 5921065 }}</ref> The higher cognition of the humans is instead seen to relate to a greater connectedness given by [[nerve tract|neural tracts]] that do not affect the cortical volume.<ref name="Semendeferi"/> This is also evident in the [[neural pathway|pathways]] of the [[large scale brain networks|language network]] connecting the frontal and temporal lobes.<ref name="Friederici">{{cite journal | vauthors = Friederici AD | title = Pathways to language: fiber tracts in the human brain | journal = Trends in Cognitive Sciences | volume = 13 | issue = 4 | pages = 175–81 | date = April 2009 | pmid = 19223226 | doi = 10.1016/j.tics.2009.01.001 | s2cid = 15609709 }}</ref>

== See also ==
{{Anatomy-terms}}
*[[Broca's area]]
*[[Limen insulae]]
*[[List of regions in the human brain]]

== References ==
{{reflist}}

==Further reading==
*Donald T. Stuss and Robert T. Knight (Eds.), ''Principles of Frontal Lobe Function'', Second Edition, Oxford University Press, New York, 2013.

== External links ==
{{Commons category|Frontal lobe}}
* [https://www.neuinfo.org/mynif/search.php?q=Frontal%20Lobe&t=data&s=cover&b=0&r=20 NIF Search – Frontal Lobe] {{Webarchive|url=https://web.archive.org/web/20130703215911/https://www.neuinfo.org/mynif/search.php?q=Frontal%20Lobe&t=data&s=cover&b=0&r=20 |date=2013-07-03 }} via the [[Neuroscience Information Framework]]

{{Prosencephalon}}

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{{DEFAULTSORT:Frontal Lobe}}
[[Category:Frontal lobe| ]]
[[Category:Cerebrum]]
[[Category:Brain]]
[[Category:Neurology]]