White Matter Flashcards
Arcuate fasciculus
Language pathway, connecting temporal, parietal and inferior frontal lobes, linking the receptive Wernicke’s and the expressive Broca’s speech centers
Uncinate fasciculus
Connecting mesial temporal structures within the orbitofrontal cortex and frontal pole
Superior longitudinal fasciculus
Major fronto-parietal connection, visuospatial, reaching grasping, SLF I, II and III
Inferior longitudinal fasciculus
Connects the temporal and occipital lobes merges with the inferior fronto-occipital fasciculus (IFOF)
Inferior fronto-occipital fasciculus
Longest association tract . Frontal lobe to occipital lobe
Frontal aslant tract
Inferior frontal gyrus (lateral) to the pre-supplementary and supplementary motor areas of the Superior frontal gurys (medial).
What is the role of commissural fibers?
Cross midline to connect the two cerebral hemispheres
Name the main commissural fibers
Corpus callosum
Anterior Commissure
Hippocampal commissure
Posterior commisure
Name the parts of the Corpus Callosum from anteriorly to posteriorly
Rostrum, genu, body, isthmus, splenium
What is the lamina terminalis ?
The most rostral aspect of the early neural tube and anterior neuropore
What does the line of Talairach-Tournoux connect?
A line through AC-PC
What are the three types of white matter fibers?
- Projection fibers (ascending or descending)
- Commisural fibers (corpus callosum)
- Association fibers (connecting cortex of the same hemisphere)
In a FA/direction DTI map which fibers are blue, green and red?
Blue = foot to head Red = Right to left Green = Anterior to posterior
Which tracts make up the Pyramidal tract?
Corticospinal tract (muscles of the body) Corticobulbar tract (muscles of the head)
Name the projection tracks
- Pyramidal tract
- Corticopontine tract
- Brainstem tract (medial lemniscus)
- Optic radiation
Corticobulbar tract
Fibers from the lateral frontal lobe (motor cortex), go to the brainstem where the innervate the nuclei of the cranial nerves. All bilateral innervation except facial and hypoglossal nerves unilatera!
Describe connection of Optic radiation
Lateral geniculate nucleus to the primary visual cortex (geniculocalcarine tract)
Name a complication of temporal lobe Epilepsy surgery
Post-operative visual field defects in 50-100%
Name the parts of the optic radiation
Posterior, central and anterior bundles
what is the Meyer’s loop?
Part of the anterior bundle of the optic radiation which curves around the temporal horn
Does DTI show lateral fibers of the corpus callosum?
No DTI , can only show medial fibers
In anterior or posterior callosal disconnection the symptoms can be often subclinical?
Anterior (genu, ant body)
What functions are projected more posteriorly in the corpus callosum?
Auditory and visual
Which association tracts are associated with language ?
SLF/Arcuate fasciculus
Uncinate Fasciculus
Inferior fronto-occipital fasciculus
Frontal Aslant Tract
what is the safe distance between a tract and a tumour on DTI?
> 1cm. If the tract is less than 1cm away from the tumour then needs electrical stimulation
Operative electrical stimulation (mapping )or DTI is more accurate?
Operative mapping is the gold standard
Depending on the location what will a lesion cause
if in Broca’s area? Wernicke’s area? Arcuate fasciculus?
Broca’s: Expressive aphasia
Wernicke’s :Receptive aphasia
AF: Conduction aphasia
Isotropic diffusion
Anisotropic diffusion
Like a ball (all directions)
Like a rugby ball (specific direction of fibers)
What is FA?
Fractional Anisotropy Map
what is the role of Projection fibers
Connect cortex with other parts of the CNS
Is the corticospinal tract purely motor?
No receives 30% of fibers from post central gyrus (sensory)
Modern model of language pathway
Ventral :semantic: anterior middle TL speech comprehension Bilateral
Dorsal: Phonological: sensorimotor Dominant
Lateralisation of AF and Frontal Aslant tracts
Left-lateralised
