The superior longitudinal fasciculus (SLF) is an

association Association may refer to: *Club (organization), an association of two or more people united by a common interest or goal *Trade association, an organization founded and funded by businesses that operate in a specific industry *Voluntary associatio ...

tract Tract may refer to: Geography and real estate * Housing tract, an area of land that is subdivided into smaller individual lots * Land lot or tract, a section of land * Census tract, a geographic region defined for the purpose of taking a census ...

in the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...

that is composed of three separate components. It is present in both hemispheres and can be found

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction *Lateral cricoarytenoid muscle *Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral cons ...

to the

centrum semiovale In neuroanatomy, the centrum semiovale, semioval center or centrum ovale is the central area of white matter found underneath the cerebral cortex. The white matter, located in each hemisphere between the cerebral cortex and nuclei, as a whole ha ...

and connects the

frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music * The Front (band), an American rock band signed to Columbia Records and active in the 1980s and e ...

occipital The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...

, parietal, and

temporal lobe The temporal lobe is one of the four Lobes of the brain, major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe ...

s. This bundle of tracts (fasciculus) passes from the frontal lobe through the operculum to the posterior end of the

lateral sulcus In neuroanatomy, the lateral sulcus (also called Sylvian fissure, after Franciscus Sylvius, or lateral fissure) is one of the most prominent features of the human brain. The lateral sulcus is a deep fissure in each hemisphere that separates the ...

where they either radiate to and synapse on neurons in the occipital lobe, or turn downward and forward around the

putamen The putamen (; from Latin, meaning "nutshell") is a round structure located at the base of the forebrain (telencephalon). The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that compose the basal n ...

and then radiate to and synapse on neurons in anterior portions of the temporal lobe. The SLF is composed of three distinct components SLF I, SLF II, and SLF III.

SLF I

SLF I is the dorsal component and originates in the superior and medial

parietal cortex The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus. The parietal lobe integrates sensory inform ...

, passes around the

cingulate sulcus The cingulate sulcus is a sulcus (brain fold) on the cingulate cortex in the medial wall of the cerebral cortex. The frontal and parietal lobes are separated from the cingulate gyrus by the cingulate sulcus. It terminates as the marginal sulcus o ...

and in the superior parietal and frontal white matter, and terminates in the dorsal and medial cortex of the frontal lobe ( Brodmann 6, 8, and 9) and in the supplementary motor cortex (M II). SLF I connects to the superior parietal cortex which encodes locations of body parts in a body-centric coordinate system and with M II and dorsal

premotor cortex The premotor cortex is an area of the motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex. It occupies part of Brodmann's area 6. It has been studied mainly in primates, including monkeys and humans. ...

. This suggests the SLF I is involved with regulating motor behavior, especially conditional associative tasks which select among competing motor tasks based on conditional rules.

SLF II

SLF II is the major component of SLF and originates in the caudal-inferior parietal cortex and terminates in the

dorsolateral prefrontal cortex The dorsolateral prefrontal cortex (DLPFC or DL-PFC) is an area in the prefrontal cortex of the primate brain. It is one of the most recently derived parts of the human brain. It undergoes a prolonged period of maturation which lasts until adultho ...

(Brodmann 6, 8 and 46). SLF II connects to the caudal inferior parietal cortex which controls spatial attention and visual and

oculomotor The oculomotor nerve, also known as the third cranial nerve, cranial nerve III, or simply CN III, is a cranial nerve that enters the orbit (anatomy), orbit through the superior orbital fissure and innervates extraocular muscles that enable mo ...

functions. This suggests the SLF II provides the prefrontal cortex with parietal cortex information regarding perception of

visual space Visual space is the experience of space by an aware observer. It is the subjective counterpart of the space of physical objects. There is a long history in philosophy, and later psychology of writings describing visual space, and its relationship ...

. Since these bundles are bi-directional,

working memory Working memory is a cognitive system with a limited capacity that can 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 memory, ...

(Brodmann 46) in the prefrontal cortex may provide the parietal cortex with information to focus spatial attention and regulate selection and retrieval of spatial information.

SLF III

SLF III is the ventral component and originates in the

supramarginal gyrus The supramarginal gyrus is a portion of the parietal lobe. This area of the brain is also known as Brodmann area 40 based on the brain map created by Korbinian Brodmann to define the structures in the cerebral cortex. It is probably involved wit ...

(rostral portion of the inferior parietal lobe) and terminates in the ventral premotor and

prefrontal cortex In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, ...

(Brodmann 6, 44, and 46). SLF III connects the rostral inferior parietal cortex which receives information from the ventral

precentral gyrus The precentral gyrus is a prominent gyrus on the surface of the posterior frontal lobe of the brain. It is the site of the primary motor cortex that in humans is cytoarchitecturally defined as Brodmann area 4. Structure The precentral gyrus l ...

. This suggests that the SLF III transfers somatosensory information, such as language articulation, between the ventral

, Brodmann 44 (

pars opercularis The inferior frontal gyrus (IFG), (gyrus frontalis inferior), is the lowest positioned gyrus of the frontal gyri, of the frontal lobe, and is part of the prefrontal cortex. Its superior border is the inferior frontal sulcus (which divides it from ...

), the

( Brodmann 40), and the laterial inferior prefrontal cortex working memory (Brodmann 46).

References

External links

Brainmind.com atlas, see "1. Short arcuate bundles" section. Bundle 2 is the superior longitudinal fasciculus

brain atlas sagittal images showing the SLF (bundle 2)
* - "Dissection of the Left Hemisphere" {{Authority control Central nervous system pathways Cerebral white matter