Document Detail

Visual thresholds in albino and pigmented rats.
MedLine Citation:
PMID:  1390398     Owner:  NLM     Status:  MEDLINE    
Albino rats have recently been reported to have increment thresholds against dim backgrounds that are two log units higher than those of pigmented rats. We, on the other hand, have failed to confirm these differences using electroretinogram b-waves and pupillary light reflexes. This paper reports on experiments using evoked potentials from cortex and colliculus and single-unit recordings from colliculus. We recorded visual-evoked potentials from cortex and superior colliculus in the strains of albino (CD) and pigmented (Long-Evans) rats used in the earlier studies. Thresholds were determined on eight fully dark-adapted animals by extrapolating intensity-response curves to the point at which there was zero evoked potential. The average dark-adapted threshold for the visual-evoked cortical potential was -5.6 log cd/m2 in pigmented and -5.80 log cd/m2 in albino animals. The average dark-adapted threshold for the superior colliculus evoked response was -5.54 log cd/m2 in pigmented and -5.84 log cd/m2 in albinos. The differences were not statistically significant. On the same apparatus, the average absolute threshold for three human observers was -5.3 log cd/m2, a value close to the rat dark-adapted thresholds. Thus, visual-evoked cortical potentials and superior collicular evoked potentials failed to confirm the report of higher dark-adapted thresholds for albinos. In addition, we find that single units in superior colliculus in the albino rat respond to very dim flashes.
P Herreros de Tejada; D G Green; C Muñoz Tedó
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Visual neuroscience     Volume:  9     ISSN:  0952-5238     ISO Abbreviation:  Vis. Neurosci.     Publication Date:    1992 Sep-Oct
Date Detail:
Created Date:  1992-11-02     Completed Date:  1992-11-02     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8809466     Medline TA:  Vis Neurosci     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  409-14     Citation Subset:  IM    
Department of Ophthalmology, University of Michigan, Ann Arbor 48104-1687.
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MeSH Terms
Albinism / physiopathology
Dark Adaptation
Evoked Potentials, Visual
Sensory Thresholds*
Superior Colliculi / physiology*
Visual Cortex / physiology*
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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