Spyridon Komaitis1,2,3, Aristotelis V Kalyvas1,2,3, Georgios P Skandalakis1,3, Evangelos Drosos1,2, Evgenia Lani1,3, Evangelia Liouta4, Faidon Liakos1, Theodosis Kalamatianos4, Maria Piagkou3, John A Emelifeonwu5,6, George Stranjalis1,2,4, Christos Koutsarnakis1,2,3,6. 1. 1Athens Microneurosurgery Laboratory, National and Kapodistrian University of Athens School of Medicine, Athens. 2. 2Department of Neurosurgery, National and Kapodistrian University of Athens. 3. 3Department of Anatomy, National and Kapodistrian University of Athens School of Medicine, Athens, Greece. 4. 6Hellenic Center for Neurosurgical Research, "Petros Kokkalis," Athens, Greece. 5. 4Department of Clinical Neurosciences, Western General Hospital, Edinburgh. 6. 5Department of Clinical Neurosciences, Edinburgh Microneurosurgery Education Laboratory, Edinburgh, UK; and.
Abstract
OBJECTIVE: The purpose of this study was to investigate the morphology, connectivity, and correlative anatomy of the longitudinal group of fibers residing in the frontal area, which resemble the anterior extension of the superior longitudinal fasciculus (SLF) and were previously described as the frontal longitudinal system (FLS). METHODS: Fifteen normal adult formalin-fixed cerebral hemispheres collected from cadavers were studied using the Klingler microdissection technique. Lateral to medial dissections were performed in a stepwise fashion starting from the frontal area and extending to the temporoparietal regions. RESULTS: The FLS was consistently identified as a fiber pathway residing just under the superficial U-fibers of the middle frontal gyrus or middle frontal sulcus (when present) and extending as far as the frontal pole. The authors were able to record two different configurations: one consisting of two distinct, parallel, longitudinal fiber chains (13% of cases), and the other consisting of a single stem of fibers (87% of cases). The fiber chains' cortical terminations in the frontal and prefrontal area were also traced. More specifically, the FLS was always recorded to terminate in Brodmann areas 6, 46, 45, and 10 (premotor cortex, dorsolateral prefrontal cortex, pars triangularis, and frontal pole, respectively), whereas terminations in Brodmann areas 4 (primary motor cortex), 47 (pars orbitalis), and 9 were also encountered in some specimens. In relation to the SLF system, the FLS represented its anterior continuation in the majority of the hemispheres, whereas in a few cases it was recorded as a completely distinct tract. Interestingly, the FLS comprised shorter fibers that were recorded to interconnect exclusively frontal areas, thus exhibiting different fiber architecture when compared to the long fibers forming the SLF. CONCLUSIONS: The current study provides consistent, focused, and robust evidence on the morphology, architecture, and correlative anatomy of the FLS. This fiber system participates in the axonal connectivity of the prefrontal-premotor cortices and allegedly subserves cognitive-motor functions. Based in the SLF hypersegmentation concept that has been advocated by previous authors, the FLS should be approached as a distinct frontal segment within the superior longitudinal system.
OBJECTIVE: The purpose of this study was to investigate the morphology, connectivity, and correlative anatomy of the longitudinal group of fibers residing in the frontal area, which resemble the anterior extension of the superior longitudinal fasciculus (SLF) and were previously described as the frontal longitudinal system (FLS). METHODS: Fifteen normal adult formalin-fixed cerebral hemispheres collected from cadavers were studied using the Klingler microdissection technique. Lateral to medial dissections were performed in a stepwise fashion starting from the frontal area and extending to the temporoparietal regions. RESULTS: The FLS was consistently identified as a fiber pathway residing just under the superficial U-fibers of the middle frontal gyrus or middle frontal sulcus (when present) and extending as far as the frontal pole. The authors were able to record two different configurations: one consisting of two distinct, parallel, longitudinal fiber chains (13% of cases), and the other consisting of a single stem of fibers (87% of cases). The fiber chains' cortical terminations in the frontal and prefrontal area were also traced. More specifically, the FLS was always recorded to terminate in Brodmann areas 6, 46, 45, and 10 (premotor cortex, dorsolateral prefrontal cortex, pars triangularis, and frontal pole, respectively), whereas terminations in Brodmann areas 4 (primary motor cortex), 47 (pars orbitalis), and 9 were also encountered in some specimens. In relation to the SLF system, the FLS represented its anterior continuation in the majority of the hemispheres, whereas in a few cases it was recorded as a completely distinct tract. Interestingly, the FLS comprised shorter fibers that were recorded to interconnect exclusively frontal areas, thus exhibiting different fiber architecture when compared to the long fibers forming the SLF. CONCLUSIONS: The current study provides consistent, focused, and robust evidence on the morphology, architecture, and correlative anatomy of the FLS. This fiber system participates in the axonal connectivity of the prefrontal-premotor cortices and allegedly subserves cognitive-motor functions. Based in the SLF hypersegmentation concept that has been advocated by previous authors, the FLS should be approached as a distinct frontal segment within the superior longitudinal system.
Authors: Qinglu Yang; Shruti Nanivadekar; Paul A Taylor; Zulin Dou; Codrin I Lungu; Silvina G Horovitz Journal: Neurosci Lett Date: 2020-11-05 Impact factor: 3.046
Authors: Emanuele La Corte; Daniela Eldahaby; Elena Greco; Domenico Aquino; Giacomo Bertolini; Vincenzo Levi; Malte Ottenhausen; Greta Demichelis; Luigi Michele Romito; Francesco Acerbi; Morgan Broggi; Marco Paolo Schiariti; Paolo Ferroli; Maria Grazia Bruzzone; Graziano Serrao Journal: Front Neurol Date: 2021-02-24 Impact factor: 4.003