Superior longitudinal fasciculus
Encyclopedia
The superior longitudinal fasciculus (also called the superior longitudinal fascicle or SLF) is a pair of long bi-directional bundles of neurons connecting the front and the back of the cerebrum. Each association fiber bundle is lateral to the centrum ovale of a cerebral hemisphere
and connects the frontal, occipital, parietal, and temporal lobe
s. The neurons pass from the frontal lobe
through the operculum to the posterior end of the lateral sulcus where numerous neurons radiate into the occipital lobe
and other neurons turn downward and forward around the putamen
and radiate to anterior portions of the temporal lobe.
6, 8, and 9) and in the supplementary motor cortex (M II).
(Brodmann 6, 8 and 46).
(Brodmann 6, 44, and 46).
and passes next to the neurons of SLF II above the Sylvian fissure and insula
in non-human primates. In humans, neurons that originate from the caudal superior temporal gyrus and the superior temporal sulcus pass around the caudal Sylvian fissure and along with the SLF bundle and terminate in the dorsal prefrontal cortex
(Brodmann areas 8 and 46).
, Brodmann 44 (pars opercularis
), the supramarginal gyrus
(Brodmann 40), and the laterial inferior prefrontal cortex working memory (Brodmann 46).
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 connects the frontal, occipital, parietal, and 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. The neurons pass from 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...
through the operculum to the posterior end of the lateral sulcus where numerous neurons radiate into the occipital lobe
Occipital lobe
The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1...
and other neurons turn downward and forward around the putamen
Putamen
The putamen is a round structure located at the base of the forebrain . The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that comprises the basal ganglia. Through various pathways, the putamen is connected to the substantia nigra and globus pallidus...
and radiate to anterior portions of the temporal lobe.
Anatomy
The SLF is composed of four distinct components SLF I, SLF II, SLF III, and arcuate fascicle (AF). In humans, these four components are bundled together although they are functionally separate. In non-human primates, the SLF and AF are anatomically separate and have separate trajectories.SLF I
SLF I is the dorsal component and originates in the superior and medial parietal cortex, passes around the cingulate sulcus and in the superior parietal and frontal white matter, and terminates in the dorsal and medial cortex of the frontal lobe (BrodmannBrodmann
Brodmann may refer to:* Korbinian Brodmann, German neurologist* Brodmann area, a region in the brain cortex...
6, 8, and 9) and in the supplementary motor cortex (M II).
SLF II
SLF II is the major component of SLF and originates in the caudal-inferior parietal cortex and terminates in the dorsolateral prefrontal cortexDorsolateral prefrontal cortex
The dorsolateral prefrontal cortex , according to a more restricted definition, is roughly equivalent to Brodmann areas 9 and 46. According to a broader definition DL-PFC consists of the lateral portions of Brodmann areas 9 – 12, of areas 45, 46, and the superior part of area 47. These regions...
(Brodmann 6, 8 and 46).
SLF III
SLF III is the ventral component and originates in the supramarginal gyrus (rostral portion of the inferior parietal lobe) and terminates in the ventral premotor and prefrontal cortexPrefrontal 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...
(Brodmann 6, 44, and 46).
AF
The AF originates in the caudal area of the superior temporal gyrusSuperior temporal gyrus
The superior temporal gyrus is one of three gyri in the temporal lobe of the human brain, which is located laterally to the head, situated somewhat above the external ear.The superior temporal gyrus is bounded by:* the lateral sulcus above;...
and passes next to the neurons of SLF II above the Sylvian fissure and insula
Insular cortex
In each hemisphere of the mammalian brain the insular cortex is a portion of the cerebral cortex folded deep within the lateral sulcus between the temporal lobe and the frontal lobe. The cortical area overlying it towards the lateral surface of the brain is the operculum...
in non-human primates. In humans, neurons that originate from the caudal superior temporal gyrus and the superior temporal sulcus pass around the caudal Sylvian fissure and along with the SLF bundle and terminate in the dorsal 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...
(Brodmann areas 8 and 46).
SLF I
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. 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 connects to the caudal inferior parietal cortex which controls spatial attention and visual and oculomotor functions. This suggests the SLF II provides the prefrontal cortex with parietal cortex information regarding perception of visual space. Since these bundles are bi-directional, working 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 connects the rostral inferior parietal cortex which receives information from the ventral precentral gyrus. This suggests that the SLF III transfers somasensory information, such as language articulation, between the ventral premotor cortexPremotor cortex
The premotor cortex is an area of motor cortex lying within the frontal lobe of the brain. It extends 3 mm anterior to the primary motor cortex, near the Sylvian fissure, before narrowing to approximately 1 mm near the medial longitudinal fissure, which serves as the posterior border for...
, Brodmann 44 (pars opercularis
Pars opercularis
In 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...
), the supramarginal gyrus
Supramarginal gyrus
The supramarginal gyrus is a portion of the parietal lobe. It is probably involved with language perception and processing, and lesions in it may cause Wernicke's aphasia or transcortical sensory aphasia.-External links:...
(Brodmann 40), and the laterial inferior prefrontal cortex working memory (Brodmann 46).
