Microsurgical anatomy of middle longitudinal fasciculus

Aim: Middle longitudinal fasciculus (MdLF) is a cortico-cortical association pathway, and originates from the temporal pole, then extends across the superior temporal gyrus and reaches the inferior parietal lobe. The aim of this anatomical study is to delineate the microsurgical anatomy of MdLF using fiber dissection technique.Material and Methods: Four formalin-fixed cadaveric human brains were dissected by Klingler method. A step-by-step dissection was utilized to expose white matter pathways, including MdLF.Results: MdLF consists of three parts: anterior, middle and posterior. The anterior part of MdLF fibers originates from the temporal pole and extends to posterior along the superior temporal gyrus. The middle part of MdLF is extended from the posterior of the Heschl gyrus to the medial of the arcuate fasciculus. The posterior part of MdLF joined the sagittal stratum together with the posterior limb of the internal capsule and inferior frontooccipital fasciculus.Conclusion: MdLF is still being studied in terms of its anatomy and functions. Considering the connections between the cortical areas with well-known functions such as superior temporal gyrus, angular gyrus and superior parietal lobule, it can be asserted that MdLF is associated with language, auditory, visual and cognitive functions.

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1. Schmahmann JD, Smith EE, Eichler FS, et al. Cerebral white matter: Neuroanatomy, clinical neurology, and neurobehavioral correlates. Ann N Y Acad Sci 2008;1142:266-309.
2. Wakana S, Jiang H, Nagae-Poetscher LM, et al. Fiber tract-based atlas of human white matter anatomy. Radiology 2004;230:77-87.
3. Makris N, Papadimitriou GM, Kaiser JR, et al. Delineation of the middle longitudinal fascicle in humans: a quantitative, in vivo, DT-MRI study. Cereb Cortex 2009;19:777-85.
4. Menjot de Champfleur N, Lima Maldonado I, Moritz- Gasser S, et al. Middle longitudinal fasciculus delineation within language pathways: A diffusion tensor imaging study in human. Eur J Radiol 2013;82:151-7.
5. Kalyvas A, Koutsarnakis C, Komaitis S, et al. Mapping the human middle longitudinal fasciculus through a focused anatomo-imaging study: shifting the paradigm of its segmentation and connectivity pattern. Brain Struct Funct 2020;225:85-119.
6. Poremba A, Saunders RC, Crane AM, et al. Functional mapping of the primate auditory system. Science 2003;299:568-72.
7. Conner AK, Briggs RG, Rahimi M, et al. A Connectomic Atlas of the Human Cerebrum-Chapter 12: Tractographic Description of the Middle Longitudinal Fasciculus, Oper Neurosurg 2018;15:429-35.
8. Seltzer B, Pandya DN. Further observations on parieto-temporal connections in the rhesus monkey. Exp Brain Res 1984;55:301-12.
9. Schmahmann JD, Pandya DN, Wang R, et al. Association fibre pathways of the brain: parallel observations from diffusion spectrum imaging and autoradiography. Brain 2007;130:630-53.
10. Maldonado IL, de Champfleur NM, Velut S, et al. Evidence of a middle longitudinal fasciculus in the human brain from fiber dissection. J Anat 2013;223:38-45.
11. Muftah Lahirish IA, Middlebrooks EH, Holanda VM, et al. Comparison Between Transcortical and Interhemispheric Approaches to the Atrium of Lateral Ventricle Using Combined White Matter Fiber Dissections and Magnetic Resonance Tractography. World Neurosurg 2020;138:478-85.
12. Fernández L, Velásquez C, García Porrero JA, et al. Heschl's gyrus fiber intersection area: a new insight on the connectivity of the auditory-language hub. Neurosurg Focus 2020;48:7.
13. Makris N, Pandya DN. The extreme capsule in humans and rethinking of the language circuitry. Brain Struct Funct 2009;213:343-58.
14. Makris N, Preti MG, Asami T, et al. Human middle longitudinal fascicle: variations in patterns of anatomical connections. Brain Struct Funct 2013;218:951-68.
15. Hickok G, Poeppel D. The cortical organization of speech processing. Nat Rev Neurosci 2007;8:393- 402.
16. Heilman KM, Van Den Abell T. Right hemisphere dominance for attention: the mechanism underlying hemispheric asymmetries of inattention (neglect). Neurology 1980;30:327-30.
17. Palejwala AH, O’Connor KP, Pelargos P, et al. Anatomy and white matter connections of the lateral occipital cortex. Surg Radiol Anat 2020;42:315-28.
18. De Witt Hamer PC, Moritz-Gasser S, Gatignol P, et al. Is the human left middle longitudinal fascicle essential for language? A brain electrostimulation study. Hum Brain Mapp 2011;32:962-73.
19. Molholm S, Sehatpour P, Mehta AD, et al. Audiovisual multisensory integration in superior parietal lobule revealed by human intracranial recordings. J Neurophysiol 2006;96:721-9.
20. Galton CJ, Patterson K, Graham K, et al. Differing patterns of temporal atrophy in Alzheimer’s disease and semantic dementia. Neurology 2001;57:216-25.
21. Luo C, Makaretz S, Stepanovic M, et al. Middle longitudinal fascicle is associated with semantic processing deficits in primary progressive aphasia. Neuroimage Clin 2020;25:102115.
22. Rajarethinam R, Sahni S, Rosenberg DR, et al. Reduced superior temporal gyrus volume in young offspring of patients with schizophrenia. Am J Psychiatry 2004;161:1121-4.
23. Asami T, Saito Y, Whitford TJ, et al. Abnormalities of middle longitudinal fascicle and disorganization in patients with schizophrenia. Schizophr Res 2013;143:253-9.
24. Sapolsky D, Bakkour A, Negreira A, et al. Cortical neuroanatomic correlates of symptom severity in primary progressive aphasia. Neurology 2010;75:358- 66.