Document Detail

Visual thalamotelencephalic pathways in the sturgeon Acipenser, a non-teleost actinopterygian fish.
MedLine Citation:
PMID:  10085481     Owner:  NLM     Status:  MEDLINE    
Terrestrial vertebrates (amphibians, reptiles, birds, and mammals) possess two visual systems, the geniculate and extrageniculate pathways to the telencephalon. In cartilaginous fishes (e.g. sharks) both retinal and tectal neurons project to neurons in the thalamus, which themselves project to a single area in the telencephalon. The condition in ray-finned fishes (Actinopterygii) is ambiguous. In many teleosts there is a well developed extrageniculate pathway but no obvious geniculate system. This study reports on the thalamotelencephalic projections of a sturgeon, a non-teleost ray-finned fish. Several tract tracing methods (e.g., HRP, WGA-HRP, biocytin, BDA, DiI) were employed in conjunction with normal techniques for identifying neural structures (e.g., Nissl, Golgi). After injections of tracer into retinal and tectal recipient areas of the thalamus, labeled terminals were observed in the ventrolateral region of the caudal telencephalon, an area referred to as the thalamic projection area. After injections of tracer into the telencephalon, populations of retrogradely filled neurons were located in both the dorsal and ventral thalamus. These data demonstrate that thalamic neurons in both retinal and tectal pathways project directly to the telencephalon. These results support the view that two visual pathways are a primitive feature of vertebrate brain organization. These results are also consistent with the hypothesis that the ancestor of Acipenser and Teleostei (Actinopteri) acquired a novel visual pathway to the telencephalon through the ventral portion of the thalamus.
J S Albert; N Yamamoto; M Yoshimoto; N Sawai; H Ito
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Brain, behavior and evolution     Volume:  53     ISSN:  0006-8977     ISO Abbreviation:  Brain Behav. Evol.     Publication Date:  1999  
Date Detail:
Created Date:  1999-05-06     Completed Date:  1999-05-06     Revised Date:  2006-04-04    
Medline Journal Info:
Nlm Unique ID:  0151620     Medline TA:  Brain Behav Evol     Country:  SWITZERLAND    
Other Details:
Languages:  eng     Pagination:  156-72     Citation Subset:  IM    
Department of Anatomy and Laboratory for Comparative Neuromorphology, Nippon Medical School, Tokyo, Japan.
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MeSH Terms
Fishes / anatomy & histology*,  physiology*
Telencephalon / physiology*
Thalamus / physiology*
Visual Pathways / physiology*

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