Document Detail

Non-length-tuned cells in layers II/III and IV of the visual cortex: the effect of blockade of layer VI on responses to stimuli of different lengths.
MedLine Citation:
PMID:  7621930     Owner:  NLM     Status:  MEDLINE    
We have previously shown, using a local inactivation technique, that layer VI provides a facilitatory input to the majority of hypercomplex cells located in layer IV above, and hence to layers II/III, which in many cases enhances length selectivity. However, many cells in these layers are not tuned for stimulus length, being equally responsive to long and short stimuli. Thus it is important to known whether layer VI can influence the responses of these cells. We have now used a similar paradigm of iontophoretic application of GABA to examine the effect of blockade of layer VI on the length tuning profiles of these cells in layers II-IV. During the blockade of layer VI, the most common effect, seen in 41% of the cells, was inhibition of visual responses, (i.e. commensurate with loss of a facilitatory input). An increase in response magnitude was found in 21% of the population, and responses were unaffected in 36% of cells tested. This suggests that the predominant influence of local regions of layer VI on this cell type, located in layers II/III and IV, is facilitatory, with a smaller proportion of cells receiving an inhibitory input. Such effects were seen even with the shortest lengths tested, suggesting once more that elements of layer VI are responsive to stimuli much shorter than was previously accepted. Thus these data suggest that layer VI plays a role in the generation of the response dynamics of non-length-tuned cells in overlying layers II/III and IV.
K L Grieve; A M Sillito
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Experimental brain research     Volume:  104     ISSN:  0014-4819     ISO Abbreviation:  Exp Brain Res     Publication Date:  1995  
Date Detail:
Created Date:  1995-08-31     Completed Date:  1995-08-31     Revised Date:  2013-12-13    
Medline Journal Info:
Nlm Unique ID:  0043312     Medline TA:  Exp Brain Res     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  12-20     Citation Subset:  IM    
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MeSH Terms
GABA-A Receptor Antagonists
Muscimol / pharmacology
Photic Stimulation
Visual Cortex / cytology,  drug effects,  physiology*
gamma-Aminobutyric Acid / administration & dosage,  pharmacology
Reg. No./Substance:
0/GABA-A Receptor Antagonists; 2763-96-4/Muscimol; 56-12-2/gamma-Aminobutyric Acid

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

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