neuroanatomy Neuroanatomy is the study of the structure and organization of the nervous system. In contrast to animals with radial symmetry, whose nervous system consists of a distributed network of cells, animals with bilateral symmetry have segregated, defi ...

, the superior frontal gyrus (SFG, also marginal gyrus) is a

gyrus In neuroanatomy, a gyrus (: gyri) is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci (depressions or furrows; : sulcus). Gyri and sulci create the folded appearance of the brain in humans and other mammals. ...

– a ridge on the

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays ...

– which makes up about one third of the

frontal lobe The frontal lobe is the largest of the four major lobes of the brain in mammals, 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 (neur ...

. It is bounded laterally by the superior frontal sulcus. The superior frontal gyrus is one of the frontal gyri.

Function

Self-awareness

In fMRI experiments, Goldberg ''et al.'' have found evidence that the superior frontal gyrus is involved in

self-awareness In philosophy of self, philosophy, self-awareness is the awareness and reflection of one's own personality or individuality, including traits, feelings, and behaviors. It is not to be confused with consciousness in the sense of qualia. While ...

, in coordination with the action of the

sensory system The sensory nervous system is a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory neurons (including the sensory receptor cells), neural pathways, and parts of the brain involved ...

. The medial frontal gyrus (MFG) is the medial portion of the superior frontal gyrus. The MFG plays a crucial role implicated in self-reflection and

, particularly during self-referential processing. The MFG becomes activated when individuals engage in tasks that involve evaluating traits about themselves. This process is essential for maintaining a

sense of self A sense is a biological system used by an organism for sensation, the process of gathering information about the surroundings through the detection of stimuli. Although, in some cultures, five human senses were traditionally identified as su ...

. In this study, people with

major depressive disorder Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive depression (mood), low mood, low self-esteem, and anhedonia, loss of interest or pleasure in normally ...

, also known as MDD, showed heightened and broader activation compared to healthy individuals, indicating that the connection between MDD and the medial frontal gyrus is shown through excessive self-awareness in depression that requires greater cognitive control. This heightened activation is often linked to persistent negative self-focused thoughts. While the medial frontal gyrus plays a role in self-awareness, it also demonstrates altered activity in depression that drives maladaptive self-reflection patterns, furthering the emotional distress and inability to shift focus from negative thoughts.

Language

The superior frontal gyrus (SFG) has been identified as a brain region that is crucial to

language Language is a structured system of communication that consists of grammar and vocabulary. It is the primary means by which humans convey meaning, both in spoken and signed language, signed forms, and may also be conveyed through writing syste ...

. The SFG is thought to be associated with language functions such as spontaneity and speech initiation. Research into the connection between the gyrus and language began after the tract connecting the SFG and Broca’s area was discovered and named the “frontal aslant tract”. As further research developed investigating this tract, a reciprocal corticocortical network between the two brain regions was revealed, indicating that the language system extends beyond the well-known Broca’s and Wernicke’s areas. The newfound importance of the SFG in language has prompted researchers to further evaluate the effects of

transcranial magnetic stimulation Transcranial magnetic stimulation (TMS) is a noninvasive neurostimulation technique in which a changing magnetic field is used to induce an electric current in a targeted area of the brain through electromagnetic induction. A device called a st ...

(TMS) in patients with

aphasia Aphasia, also known as dysphasia, is an impairment in a person's ability to comprehend or formulate language because of dysfunction in specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine, but aph ...

. A 2023 study found that in patients with aphasia, the treatment group that received speech and language therapy along with rTMS in the SFG exhibited greater treatment efficiency and language improvement than the sham group.

Laughter

In 1998, neurosurgeon Itzhak Fried described a 16-year-old female patient (referred to as "patient AK") who laughed when her SFG was stimulated with

electric current An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge c ...

during treatment for

epilepsy Epilepsy is a group of Non-communicable disease, non-communicable Neurological disorder, neurological disorders characterized by a tendency for recurrent, unprovoked Seizure, seizures. A seizure is a sudden burst of abnormal electrical activit ...

. Electrical stimulation was applied to the cortical surface of AK's left

while an attempt was made to locate the focus of her epileptic seizures (which were never accompanied by laughter). Fried identified a 2 cm by 2 cm area on the left SFG where stimulation produced laughter consistently (over several trials). AK reported that the laughter was accompanied by a sensation of merriment or mirth. AK gave a different explanation for the laughter each time, attributing it to an (unfunny) external stimulus. Thus, laughter was attributed to the picture she was asked to name (saying "the horse is funny"), or to the sentence she was asked to read, or to persons present in the room ("you guys are just so funny... standing around"). Increasing the level of stimulation current increased the duration and intensity of laughter. For example, at low currents only a smile was present, while at higher currents a louder, contagious laughter was induced. The laughter was also accompanied by the stopping of all activities involving speech or hand movements.

Working Memory

The superior frontal gyrus (SFG) may play a role in

executive functions In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that support goal-directed behavior, by regulating thoughts and actions thro ...

such as self-monitoring,

working memory Working memory is a cognitive system with a limited capacity that can Memory, hold information temporarily. It is important for reasoning and the guidance of decision-making and behavior. Working memory is often used synonymously with short-term m ...

organization An organization or organisation (English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-ise, -ize (-isation, -ization), see spelling differences) is an legal entity, entity—such as ...

, and

planning Planning is the process of thinking regarding the activities required to achieve a desired goal. Planning is based on foresight, the fundamental capacity for mental time travel. Some researchers regard the evolution of forethought - the cap ...

. In a 2006 study, patients with left prefrontal lesions on the SFG exhibited poorer results on working memory tasks than the control group. Mapping showed the lateral and posterior portions of the SFG contributed the most to the working memory deficit (mostly in Brodmann area 8 in front of the frontal eye field). This study suggests the SFG is involved in executive processing.

Disorders Associated with Abnormalities of the Superior Frontal Gyrus

Abnormalities in the superior frontal gyrus are implicated in emotional and behavioral symptoms.

Atrophy Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), malnutrition, poor nourishment, poor circulatory system, circulation, loss of hormone, ...

in the superior frontal gyrus, characterized by decreased cortical thickness and gray matter volume, is associated with the severe irritability observed in youth with ADHD, disruptive mood dysregulation disorder, oppositional defiant disorder, and conduct disorder. Severe irritability is characterized by excessive sensitivity to negative emotional stimuli and impaired inhibition of

anger Anger, also known as wrath ( ; ) or rage (emotion), rage, is an intense emotional state involving a strong, uncomfortable and non-cooperative response to a perceived provocation, hurt, or threat. A person experiencing anger will often experie ...

and reactive

aggression Aggression is behavior aimed at opposing or attacking something or someone. Though often done with the intent to cause harm, some might channel it into creative and practical outlets. It may occur either reactively or without provocation. In h ...

. In a 2022 study on depressed patients with severe anhedonia (the inability to feel pleasure), the left superior frontal gyrus was shown to have high efficiency as compared to depressed patients without anhedonia. This could indicate a compensatory mechanism in response to anhedonia and could serve as a potential

biomarker In biomedical contexts, a biomarker, or biological marker, is a measurable indicator of some biological state or condition. Biomarkers are often measured and evaluated using blood, urine, or soft tissues to examine normal biological processes, ...

of anhedonia in patients diagnosed with

. A 2023 study found a positive

correlation In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statistics ...

between the cortical thickness of the superior frontal gyrus and

social anxiety Social anxiety is the anxiety and fear specifically linked to being in social settings (i.e., interacting with others). Some categories of disorders associated with social anxiety include anxiety disorders, mood disorders, autism spectrum dis ...

levels in participants with subthreshold social anxiety.

Additional images

File:Superior frontal gyrus animation small.gif, Position of superior frontal gyrus (shown in red) File:Gray725 superior frontal gyrus.png, Left cerebral hemisphere seen from above File:Gray726 superior frontal gyrus.png, Lateral surface of left cerebral hemisphere File:Gray727 superior frontal gyrus.png, Medial surface of left cerebral hemisphere File:Slide2HAN.JPG, Cerebrum. Lateral view. Deep dissection. Superior frontal gyrus labelled at top-left. File:Superior Frontal - DK ATLAS.png, Medial surface of right cerebral hemisphere. File:Superior frontal gyrus coronal sections.gif, Superior frontal gyrus highlighted in green on coronal T1 MRI images File:Superior frontal gyrus sagittal sections.gif, Superior frontal gyrus highlighted in green on sagittal T1 MRI images File:Superior frontal gyrus transversal sections.gif, Superior frontal gyrus highlighted in green on transversal T1 MRI images

References

{{Authority control Gyri Frontal lobe