Description
- Abstract:
- The likelihood of functional recovery following neural injury decreases with species complexity, maturity, and whether the injury affects the CNS or PNS. Adult vertebrates unlikely to successfully regenerate injured neurites into the CNS. This is most evident in adult mammals. Whereas there is moderate success in regenerating injured neurites peripherally, often growth cones immediately collapse upon reaching the PNS/CNS border rarely entering the transitional zone. Nonpermissive molecules located within the CNS are thought responsible for ineffective regeneration, as is the lack of limited growth-permissive/instructive molecules. Adult anurans (frogs and toads) express many of these nonpermissive molecules within their CNS, but they are able to regenerate and functionally recover into the CNS targets after nerve lesion (optic and vestibuloauditory nerve lesion (n.II and n.VIII; Sperry 1945; Zakon, 1983.) To understand how effective CNS regeneration occurs in the adult, with the goal of finding a future clinical application, we must further understand how regenerating neurites can effectively "override" nonpermissive signals and recover function without experimenter interference. Regeneration of lesioned cranial nerve (n.VIII) in anurans is studied during pre-determined recovery times. All experiments were also carried out in controls for the opportunity to compare between recovery time and treatment groups:, as follows : 1) cell "birth dating" experiments to investigate differences in mitotic patterns, new cell retention, and post-mitotic phenotypes in n.VIII targets within the medulla; 2) the anatomical extent of regeneration and target connectivity was also explored using lipophilic fluorescent tracers; 3) the vestibular postural deficits from unilateral n.VIII crush (head tilt, limb sprawl) was quantified over recovery time ; 4) and, finally, since the discovery of new genes (or transcriptomes) are expected to be central in understanding permissive regeneration within the nonpermissive CNS, the final experiment included the gene discovery technique, DD-PCR. This technique found differences in mRNA transcripts between lesioned and sham frog tissues homologous to mammalian cDNA s sequences function unknown.
- Notes:
- Thesis (Ph.D.) -- Brown University (2008)
Access Conditions
- Rights
- In Copyright
- Restrictions on Use
- Collection is open for research.
Citation
Chapman, Judith A.,
"Plasticity in the vertebrate central auditory system: Changes during development and after injury in the adult"
(2008).
Psychology Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z01J982H
