Author
Kyle P. O'Connor
Other affiliations: University of Oklahoma
Bio: Kyle P. O'Connor is an academic researcher from University of Oklahoma Health Sciences Center. The author has contributed to research in topics: Craniotomy & Aneurysm. The author has an hindex of 6, co-authored 36 publications receiving 95 citations. Previous affiliations of Kyle P. O'Connor include University of Oklahoma.
Topics: Craniotomy, Aneurysm, Clipping (medicine), Occipital lobe, Embolization
Papers
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TL;DR: In this paper, a detailed cortical model elucidating the white matter connectivity associated with this area could improve our understanding of the interacting brain networks that underlie complex human processes and postoperative outcomes related to vision and language.
48 citations
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TL;DR: The fusiform gyrus is an important region implicated in such tasks as the visual processing of human faces and bodies, as well as the perception of stimuli with high spatial frequencies, and post-surgical outcomes related to this region may be better understood in the context of the fiber-bundle anatomy highlighted by this study.
Abstract: The fusiform gyrus is understood to be involved in the processing of high-order visual information, particularly related to faces, bodies, and stimuli characterized by high spatial frequencies. A detailed understanding of the exact location and nature of associated white-tracts could significantly improve post-operative morbidity related to declining capacity. Through generalized q-sampling imaging (GQI) validated by gross dissection as a direct anatomical method of identifying white matter tracts, we have characterized these connections based on relationships to other well-known structures. We created the white matter tracts using GQI and confirmed the tracts using gross dissection. These dissections demonstrated connections to the occipital lobe from the fusiform gyrus along with longer association fibers that course through this gyrus. The fusiform gyrus is an important region implicated in such tasks as the visual processing of human faces and bodies, as well as the perception of stimuli with high spatial frequencies. Post-surgical outcomes related to this region may be better understood in the context of the fiber-bundle anatomy highlighted by this study.
36 citations
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TL;DR: The complex functional processes attributed to the lateral occipital lobe, including object recognition, facial recognition, and motion perception are likely related to the subcortical white matter tracts described within this study.
Abstract: White matter tracts link different regions of the brain, and the known functions of those interconnected regions may offer clues about the roles that white matter tracts play in information relay. The authors of this report discuss the structure and function of the lateral occipital lobe and how the lateral occipital lobe communicates with other regions via white matter tracts. The authors used generalized q-sampling imaging and cadaveric brain dissections to uncover the subcortical white matter connections of the lateral occipital lobe. The authors created GQI of ten healthy controls and dissected ten cadaveric brains. The middle longitudinal fasciculus, vertical occipital fasciculus, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, optic radiations, and a diverse array of U-shaped fibers connect the lateral occipital lobe to itself, parts of the temporal, parietal, and medial occipital cortices. The complex functional processes attributed to the lateral occipital lobe, including object recognition, facial recognition, and motion perception are likely related to the subcortical white matter tracts described within this study. There was good concordance between the white matter tracts generated using GQI and the white matter tracts that were found after dissection of the cadaveric brains. This article presents the anatomic connections of the lateral occipital lobe and discusses the associated functions.
26 citations
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TL;DR: Tethered cord syndrome should be included in the differential diagnosis in patients presenting with back or leg pain, somatosensory symptoms of the lower extremities, muscular weakness, urodynamic dysfunction, or bowel dysfunction, and patients should be counseled about surgical de-tethering as an option.
22 citations
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TL;DR: The emerging use of CIRT to treat skull base chordomas and chondrosarcomas appear promising with regard to tumor control, overall survival, and risk profile of early and late toxicity.
Abstract: Carbon ion radiotherapy (CIRT) is an emerging radiation therapy to treat skull base chordomas and chondrosarcomas. To date, its use is limited to a few centers around the world, and there has been no attempt to systematically evaluate survival and toxicity outcomes reported in the literature. Correspondingly, the aim of this study was to qualitatively and quantitatively assess these outcomes. A systematic search of seven electronic databases from inception to November 2019 was conducted following PRISMA guidelines. Articles were screened against pre-specified criteria. Outcomes were then pooled by random-effects meta-analyses of proportions. A total of nine studies provided unique metadata for assessment, with six originating from Heidelberg, Germany. The surveyed cohort size was 632 patients, with 389 (62%) chordomas and 243 (38%) chondrosarcomas of the skull base. Across all studies, median cohort age at therapy and female proportion were 46 years and 51% respectively. Estimates of local control incidence at 1-, 5-, and 10-years in chordoma-only studies were 99%, 80%, and 56%, and in chondrosarcoma-only studies were 99%, 89%, and 88%. Estimates of overall survival probability at 1-, 5-, and 10-years in chordoma-only studies were 100%, 94%, and 78%, and in chondrosarcoma-only studies were 99%, 95%, and 79%. The incidence of early and late toxicity (Grade ≥ 3) ranged from 0 to 4% across all study groups. The emerging use of CIRT to treat skull base chordomas and chondrosarcomas appear promising with regard to tumor control, overall survival, and risk profile of early and late toxicity. The current literature suffers from the fact only a few centers in the world currently employ this technology.
21 citations
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01 Jan 1995
TL;DR: Evidence for an intermediate link in the chain of processing stages leading to object recognition in human visual cortex is reported, which suggests that the enhanced responses to objects were not a manifestation of low-level visual processing.
Abstract: Thestages ofintegration leading fromlocal feature analysis toobject recognition wereexplored inhuman visual cortex byusing thetechnique offunctional magnetic resonance imaging. Herewereport evidence forobject-related activation. Suchactivation waslocated atthelateral-posterior aspect oftheoccipital lobe, just abutting theposterior aspect ofthemotion-sensitive areaMT/V5,inaregion termed the lateral occipital complex (LO). LOshowedpreferential acti- vation toimages ofobjects, compared toawiderangeof texture patterns. Thisactivation wasnotcaused byaglobal difference intheFourier spatial frequency content ofobjects versus texture images, since object images produced enhanced LOactivation compared totextures matched inpowerspectra butrandomized inphase. Thepreferential activation toob- jects alsocould notbeexplained bydifferent patterns ofeye movements: similar levels ofactivation wereobserved when subjects fixated ontheobjects andwhentheyscanned the objects withtheir eyes. Additional manipulations suchas spatial frequency filtering anda4-fold change invisual size didnotaffect LO activation. Theseresults' suggest thatthe enhanced responses toobjects werenotamanifestation of low-level visual processing. A striking demonstration that activity inLOisuniquely correlated toobject detectability was produced bythe"Lincoln" illusion, inwhichblurring of objects digitized intolarge blocks paradoxically increases their recognizability. Suchblurring ledtosignificant en- hancement ofLOactivation. Despite thepreferential activa- tion toobjects, LO didnotseemtobeinvolved inthefinal, "semantic," stages oftherecognition process. Thus,objects varying widely intheir recognizability (e.g., famous faces, commonobjects, andunfamiliar three-dimensional abstract sculptures) activated ittoasimilar degree. Theseresults are thusevidence foranintermediate linkinthechainofpro- cessing stages leading toobject recognition inhumanvisual cortex.
118 citations
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TL;DR: In this paper, a detailed cortical model elucidating the white matter connectivity associated with this area could improve our understanding of the interacting brain networks that underlie complex human processes and postoperative outcomes related to vision and language.
48 citations
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TL;DR: Understanding the mechanisms by which RT modulates immune signaling and the key players involved in modulating the RT-mediated immune response will help to improve therapeutic efficacy and to identify novel immunomodulatory drugs that will benefit cancer patients undergoing targeted RT.
Abstract: Radiation therapy (RT), an integral component of curative treatment for many malignancies, can be administered via an increasing array of techniques. In this review, we summarize the properties and application of different types of RT, specifically, conventional therapy with x-rays, stereotactic body RT, and proton and carbon particle therapies. We highlight how low-linear energy transfer (LET) radiation induces simple DNA lesions that are efficiently repaired by cells, whereas high-LET radiation causes complex DNA lesions that are difficult to repair and that ultimately enhance cancer cell killing. Additionally, we discuss the immunogenicity of radiation-induced tumor death, elucidate the molecular mechanisms by which radiation mounts innate and adaptive immune responses and explore strategies by which we can increase the efficacy of these mechanisms. Understanding the mechanisms by which RT modulates immune signaling and the key players involved in modulating the RT-mediated immune response will help to improve therapeutic efficacy and to identify novel immunomodulatory drugs that will benefit cancer patients undergoing targeted RT.
30 citations
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TL;DR: In this article, a detailed understanding of the subcortical white matter tracts connected within the MFG can facilitate improved navigation of white matter lesions in and around this gyrus and explain the postoperative morbidity after surgery.
30 citations
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TL;DR: A systematic review of studies that associate functions and clinical symptoms with individual tracts using diffusion tractography suggests that tract-function correlations might be a promising biomarker for precision medicine as it characterises variations in brain anatomy, differences in functional organisation and predict resilience or recovery in patients.
Abstract: Inter-individual differences can inform treatment procedures and - if accounted for - can significantly improve patient outcomes. However, when studying brain anatomy, these inter- individual variations are largely unaccounted for, despite reports of differences in gross anatomical features, cross-sectional and connectional anatomy. Brain connections are essential to mediate brain functional organisation and, when severed, cause functional impairments or complete loss of function. Hence the study of cerebral white matter may be an ideal compromise to capture inter-individual variability in structure and function. Here we reviewed the wealth of studies that associate functions and clinical symptoms with individual tracts using diffusion tractography. Our systematic review indicates that tractography has proven to be a sensitive method in neurology, psychiatry and healthy populations to identify variability and its functional correlates. However, the literature may be biased, as we identified that the most commonly reported tracts are not necessarily those with the highest sensitivity to cognitive functions and pathologies. Finally, we demonstrate that tracts, as we define them, are not usually correlated with only one, but rather multiple cognitive domains or pathologies. While our systematic review identified some methodological caveats, it also suggests that tract-function correlations might be a promising biomarker for precision medicine as it characterises variations in brain anatomy, differences in functional organisation and predict resilience or recovery in patients.
26 citations