Vol.:(0123456789) 1 3 Brain Structure and Function https://doi.org/10.1007/s00429-018-01822-4 ORIGINAL ARTICLE Sledge runner fasciculus: anatomic architecture and tractographic morphology Christos Koutsarnakis 1,2,3,7  · Aristotelis. V. Kalyvas 1,3,7  · Georgios P. Skandalakis 1,6  · Efstratios Karavasilis 4  · Foteini Christidi 4,5  · Spyridon Komaitis 1,3,7  · George Velonakis 4  · Faidon Liakos 1  · John Emelifeonwu 1,2  · Zoi Giavri 8  · Theodosis Kalamatianos 7  · Nikolaos Kelekis 4  · George Stranjalis 1,3,7 Received: 16 March 2018 / Accepted: 19 December 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract The sledge runner fasciculus (SRF) has been recently identifed as a discrete fber tract of the occipital lobe and has been allegedly implicated in the axonal connectivity of cortical areas conveying spatial navigation and visuospatial imagery. However, detailed knowledge regarding its anatomic and tractographic morphology is lacking. We thus opted to investigate the anatomy and connectivity of the SRF through cadaveric dissections and DTI studies. Twenty normal, adult, cerebral, cadaveric hemispheres treated with the Klingler’s method were dissected through the fber microdissection technique and 35 healthy participants from the MGH-USC Adult Difusion Dataset (Human Connectome available dataset) underwent a tailored DTI protocol aiming to investigate the structural architecture of the SRF. SR was identifed as a discrete fber path- way, just under the U fbers of the medial occipital lobe, exhibiting a dorsomedial–ventrolateral trajectory and connecting the cortical areas of the anterior cuneus, anterior lingula, isthmus of the cingulum and posterior parahippocampal gyrus. The topography of the SR in relation to adjacent fber pathways such as the cingulum, major forceps and stratum calcari- num is clearly delineated. Dissection and tractographic fndings showed a good correspondence regarding SR topography, morphology and axonal connectivity. Our results support the hypothesis that the SRF is involved in the structural axonal connectivity of cerebral areas that strongly activate during spatial navigation and visuospatial imagery. Furthermore detailed anatomo-imaging evidence is provided on the microanatomic architecture of this newly discovered fber tract. Keywords Sledge runner · Brain connectivity · White matter anatomy · Occipital lobe · Visuospatial imagery · Spatial navigation Christos Koutsarnakis and Aristotelis. V. Kalyvas contributed equally to this study. * Christos Koutsarnakis ckouts@hotmail.co.uk 1 Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece 2 Edinburgh Microneurosurgery Education Laboratory, Department of Clinical Neurosciences, Western General Hospital, Edinburgh, UK 3 Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece 4 2nd Department of Radiology, Medical School, General University Hospital “Attikon”, National and Kapodistrian University of Athens, Athens, Greece 5 1st Department of Neurology, Medical School, Aeginition Hospital, National and Kapodistrian University of Athens, Athens, Greece 6 Medical School, National and Kapodistrian University of Athens, Athens, Greece 7 Hellenic Center for Neurosurgical Research, “Petros Kokkalis”, Athens, Greece 8 Department of Electrical and Computer Engineering, National Technical University of Athens, Athens, Greece