• Login
    View Item 
    •   Home
    • Theses and Dissertations
    • Theses and Dissertations
    • View Item
    •   Home
    • Theses and Dissertations
    • Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of TUScholarShareCommunitiesDateAuthorsTitlesSubjectsGenresThis CollectionDateAuthorsTitlesSubjectsGenres

    My Account

    LoginRegister

    Help

    AboutPeoplePoliciesHelp for DepositorsData DepositFAQs

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Representation of the stationary visual environment in the anterior thalamus of the leopard frog

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    Skorina_temple_0225E_11567.pdf
    Size:
    8.910Mb
    Format:
    PDF
    Download
    Genre
    Thesis/Dissertation
    Date
    2013
    Author
    Skorina, Laura
    Advisor
    Gruberg, Edward R.
    Committee member
    Sheffield, Joel B.
    Hsieh, Tonia
    Saidel, William
    Department
    Biology
    Subject
    Biology
    Frogs
    Neuroethology
    Stationary Objects
    Thalamus
    Visual System
    Permanent link to this record
    http://hdl.handle.net/20.500.12613/2406
    
    Metadata
    Show full item record
    DOI
    http://dx.doi.org/10.34944/dspace/2388
    Abstract
    The optic tectum of the leopard frog has long been known to process visual information about prey and looming threats, stimuli characterized by their movement in the visual field. However, atectal frogs can still respond to the stationary visual environment, which therefore constitutes a separate visual subsystem in the frog. The present work seeks to characterize the stationary visual environment module in the leopard frog, beginning with the hypothesis that this module is located in the anterior thalamus, among two retinorecipient neuropil regions known as neuropil of Bellonci (NB) and corpus geniculatum (CG). First, the puzzle of how a stationary frog can see the stationary environment, in the absence of the eye movements necessary for persistence of vision, is resolved, as we show that whole-head movements caused by the frog's respiratory cycles keep the retinal image in motion. Next, the stationary visual environment system is evaluated along behavioral, anatomic, and physiological lines, and connections to other brain areas are elucidated. When the anterior thalamic visual center is disconnected, frogs show behavioral impairments in visually navigating the stationary world. Under electrophysiological probing, neurons in the NB/CG region show response properties consistent with their proposed role in processing information about the stationary visual environment: they respond to light/dark and color information, as well as reverse-engineered "stationary" stimuli (reproducing the movement on the retina of the visual backdrop caused by the frog's breathing movements), and they do not habituate. We show that there is no visuotopic map in the anterior thalamus but rather a nasal-ward constriction in the receptive fields of progressively more caudal cell groups in the NB/CG region. Furthermore, each side of the anterior thalamic visual region receives information from only the contralateral half of the visual field, as defined by the visual midline, resulting from a pattern of partial crossing over of optic nerve fibers that is also seen in the mammalian thalamic visual system, a commonality with unknown evolutionary implications. We show that the anterior thalamic visual region shares reciprocal connections with the same area on the opposite side of the brain, as well as with the posterior thalamus on both sides; there is also an anterograde ipsilateral projection from the NB/CG toward the medulla and presumably pre-motor areas.
    ADA compliance
    For Americans with Disabilities Act (ADA) accommodation, including help with reading this content, please contact scholarshare@temple.edu
    Collections
    Theses and Dissertations

    entitlement

     
    DSpace software (copyright © 2002 - 2023)  DuraSpace
    Temple University Libraries | 1900 N. 13th Street | Philadelphia, PA 19122
    (215) 204-8212 | scholarshare@temple.edu
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.