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Comer JD, Alvarez S, Butler SJ, Kaltschmidt JA. Commissural axon guidance in the developing spinal cord: from Cajal to the present day. Neural Dev 2019; 14:9. [PMID: 31514748 PMCID: PMC6739980 DOI: 10.1186/s13064-019-0133-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 08/23/2019] [Indexed: 12/11/2022] Open
Abstract
During neuronal development, the formation of neural circuits requires developing axons to traverse a diverse cellular and molecular environment to establish synaptic contacts with the appropriate postsynaptic partners. Essential to this process is the ability of developing axons to navigate guidance molecules presented by specialized populations of cells. These cells partition the distance traveled by growing axons into shorter intervals by serving as intermediate targets, orchestrating the arrival and departure of axons by providing attractive and repulsive guidance cues. The floor plate in the central nervous system (CNS) is a critical intermediate target during neuronal development, required for the extension of commissural axons across the ventral midline. In this review, we begin by giving a historical overview of the ventral commissure and the evolutionary purpose of decussation. We then review the axon guidance studies that have revealed a diverse assortment of midline guidance cues, as well as genetic and molecular regulatory mechanisms required for coordinating the commissural axon response to these cues. Finally, we examine the contribution of dysfunctional axon guidance to neurological diseases.
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Affiliation(s)
- J D Comer
- Neuroscience Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA.,Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA.,Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, USA
| | - S Alvarez
- Department of Neurobiology, University of California, Los Angeles, Los Angeles, CA, 90095, USA.,Molecular Biology Interdepartmental Graduate Program, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - S J Butler
- Department of Neurobiology, University of California, Los Angeles, Los Angeles, CA, 90095, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - J A Kaltschmidt
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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DeMar J, Sharrow K, Hill M, Berman J, Oliver T, Long J. Effects of Primary Blast Overpressure on Retina and Optic Tract in Rats. Front Neurol 2016; 7:59. [PMID: 27199884 PMCID: PMC4842954 DOI: 10.3389/fneur.2016.00059] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 04/08/2016] [Indexed: 12/19/2022] Open
Abstract
Blast has been the leading cause of injury, particularly traumatic brain injury and visual system injury, in combat operations in Iraq and Afghanistan. We determined the effect of shock tube-generated primary blast on retinal electrophysiology and on retinal and brain optic tract histopathology in a rat model. The amplitude of a- and b-waves on the electroretinogram (ERG) for both right and left eyes were measured prior to a battlefield simulation Friedlander-type blast wave and on 1, 7, and 14 days thereafter. Histopathologic findings of the right and left retina and the right and left optic tracts (2.8 mm postoptic chiasm) were evaluated 14 days after the blast. For two experiments in which the right eye was oriented to the blast, the amplitude of ERG a- and b-waves at 7 days post blast on the right side but not on the left side was diminished compared to that of sham animals (P = 0.005–0.01) Histopathologic injury scores at 14 days post blast for the right retina but not the left retina were higher than for sham animals (P = 0.01), and histopathologic injury scores at 14 days for both optic tracts were markedly higher than for shams (P < 0.0001). Exposure of one eye to a blast wave, comparable to that causing human injury, produced injury to the retina as determined by ERG and histopathology, and to both postchiasmatic optic tracts as determined by histopathology. This model may be useful for analyzing the effect of therapeutic interventions on retinal damage due to primary blast waves.
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Affiliation(s)
- James DeMar
- Blast Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research , Silver Spring, MD , USA
| | - Keith Sharrow
- Medical Countermeasures Systems, Ft. Detrick , Frederick, MD , USA
| | - Miya Hill
- Blast Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research , Silver Spring, MD , USA
| | - Jonathan Berman
- Clinical Pharmacology Department, Walter Reed Army Institute of Research , Silver Spring, MD , USA
| | - Thomas Oliver
- Clinical Research Unit, Uniformed Services University of the Health Science (USUHS) , Bethesda, MD , USA
| | - Joseph Long
- Blast Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research , Silver Spring, MD , USA
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Banihani SM. Loss of binocular vision as direct cause for misrouting of temporal retinal fibers in albinism. Med Hypotheses 2015; 85:458-62. [PMID: 26163060 DOI: 10.1016/j.mehy.2015.06.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 06/23/2015] [Accepted: 06/28/2015] [Indexed: 10/23/2022]
Abstract
In humans, the nasal retina projects to the contralateral hemisphere, whereas the temporal retina projects ipsilaterally. The nasotemporal line that divides the retina into crossed and uncrossed parts coincides with the vertical meridian through the fovea. This normal projection of the retina is severely altered in albinism, in which the nasotemporal line shifted into the temporal retina with temporal retinal fibers cross the midline at the optic chiasm. This study proposes the loss of binocular vision as direct cause for misrouting of temporal retinal fibers and shifting of the nasotemporal line temporally in albinism. It is supported by many observations that clearly indicate that loss of binocular vision causes uncrossed retinal fibers to cross the midline. This hypothesis may alert scientists and clinicians to find ways to prevent or minimize the loss of binocular vision that may occur in some diseases such as albinism and early squint. Hopefully, this will minimize the misrouting of temporal fibers and improve vision in such diseases.
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Affiliation(s)
- Saleh M Banihani
- Anatomy Dept., Medical School, Jordan University of Science and Technology, Irbid 22110, Jordan.
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Whitehead L, Banihani S. The evolution of contralateral control of the body by the brain: Is it a protective mechanism? Laterality 2013; 19:325-39. [DOI: 10.1080/1357650x.2013.824461] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Larsson M. Binocular Vision and Ipsilateral Retinal Projections in Relation to Eye and Forelimb Coordination. BRAIN, BEHAVIOR AND EVOLUTION 2011; 77:219-30. [DOI: 10.1159/000329257] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 04/11/2011] [Indexed: 11/19/2022]
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