Inferior frontal gyrus
Encyclopedia
The inferior frontal gyrus is a gyrus
of the frontal lobe
(the yellow area of the human brain image to the right). It is labelled gyrus frontalis inferior, its Latin name. In the yellow area, its superior border is the inferior frontal sulcus
(which divides it from the gyrus frontalis medius in the yellow area), its inferior border the lateral fissure
(which divides it from the gyrus temporalis superior in the green area), and its posterior border is the inferior precentral sulcus
(in the yellow area). Above it is the middle frontal gyrus
(the gyrus frontalis medius), behind it the precentral gyrus (the gyrus praecentralis), both gyri in the yellow area of the image.
The inferior frontal gyrus includes the following cytoarchitectonic areas:
The cytoarchitectonic areas very roughly correspond to the following macroanatomic structures: Brodmann area 44 to Pars opercularis, Brodmann area 45 to Pars triangularis, and Brodmann area 47 to Pars orbitalis. Brodmann area 44 corresponds to Broca's area
(sometimes Broca's area is taken to encompass Brodmann's areas 44 and 45) — for the dominant hemisphere of the brain.
The left IFG is extremely important for language production and verb comprehension. Commonly known as "Broca's Area", persons with damage in this region often have non-fluent aphasia. With non-fluent aphasia, speech is notably difficult to produce but the speech that is produced is high in content compared to Wernicke's aphasiacs (persons with damage to the posterior language regions) whose aphasia is considered "fluent" yet rambling.
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...
of the frontal lobe
Frontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
(the yellow area of the human brain image to the right). It is labelled gyrus frontalis inferior, its Latin name. In the yellow area, its superior border is the inferior frontal sulcus
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....
(which divides it from the gyrus frontalis medius in the yellow area), its inferior border the lateral fissure
Lateral sulcus
-External links:* * * http://www.uams.edu/radiology/education/residency/diagnostic/pdf/sylvian_cistern_RSNA2003.pdf...
(which divides it from the gyrus temporalis superior in the green area), and its posterior border is the inferior precentral sulcus
Precentral sulcus
The precentral sulcus lies parallel to, and in front of, the central sulcus....
(in the yellow area). Above it is the middle frontal gyrus
Middle frontal gyrus
The middle frontal gyrus makes up about one-third of the frontal lobe of the human brain....
(the gyrus frontalis medius), behind it the precentral gyrus (the gyrus praecentralis), both gyri in the yellow area of the image.
Divisions
The inferior frontal gyrus can be subdivided into the following macroanatomical structures, shown in yellow in the top image, just below the label gyrus frontalis inferior:- Pars opercularisPars opercularisIn the human brain the Pars opercularis is the part of the inferior frontal gyrus that lies between the inferior precentral sulcus and the ascending ramus of the lateral sulcus. It is called opercularis because it covers part of the insula. The pars opercularis together with the pars triangularis...
(cortex posterior to the ascending ramus of the lateral fissure) - Pars triangularisPars triangularisPars triangularis is a region of the human cortex, located in the inferior frontal gyrus of the frontal lobe in the corresponding Brodmann area 45...
(cortex between the ascending ramus and the horizontal ramus of the lateral fissure) - Pars orbitalis (cortex inferior and anterior to the horizontal ramus of the lateral fissure)
The inferior frontal gyrus includes the following cytoarchitectonic areas:
- Brodmann area 44Brodmann area 44Brodmann area 44, or BA44, is part of the frontal cortex in the human brain. Situated just anterior to premotor cortex and on the lateral surface, inferior to BA9....
- Brodmann area 45Brodmann area 45Brodmann area 45 , is part of the frontal cortex in the human brain. Situated on the lateral surface, inferior to BA9 and adjacent to BA46.This area is also known as pars triangular ...
- Brodmann area 47Brodmann area 47Brodmann area 47, or BA47, is part of the frontal cortex in the human brain. Curving from the lateral surface of the frontal lobe into the ventral frontal cortex. It is below areas BA10 and BA45, and beside BA11....
- cytoarchitectonic areas of the deep frontal operculumOperculum (brain)Operculum, derived from Latin, meaning "little lid", refers to the cerebral cortex on the outside surface of the brain bordering the lateral sulcus, and the roof and floor of the lateral sulcus. Neuroscience divides the operculum into orbital, frontal, parietal and temporal regions, after the...
The cytoarchitectonic areas very roughly correspond to the following macroanatomic structures: Brodmann area 44 to Pars opercularis, Brodmann area 45 to Pars triangularis, and Brodmann area 47 to Pars orbitalis. Brodmann area 44 corresponds to Broca's area
Broca's area
Broca'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...
(sometimes Broca's area is taken to encompass Brodmann's areas 44 and 45) — for the dominant hemisphere of the brain.
Cognitive functions
The right inferior frontal gyrus has been typically implicated in go/no go tasks. In such a task, the participant has to inhibit a prepotent response (for instance stop pressing a button when a red signal appears). It seems that the same area is also implicated in risk aversion: a study found that higher risk aversion correlated with higher activity at IFG. This might be explained as an inhibition signal to accept a risky option. Disruption of activity of this area with Transcranial Magnetic Stimulation or Direct Current Stimulation (tDCS) indeed leads to change in risk attitudes, as behaviorally demonstrated by choices over risky outcomes.The left IFG is extremely important for language production and verb comprehension. Commonly known as "Broca's Area", persons with damage in this region often have non-fluent aphasia. With non-fluent aphasia, speech is notably difficult to produce but the speech that is produced is high in content compared to Wernicke's aphasiacs (persons with damage to the posterior language regions) whose aphasia is considered "fluent" yet rambling.