Experimental Brain Research

, Volume 82, Issue 2, pp 247–253

Local axonal trajectories in mouse barrel cortex

  • K. L. Bernardo
  • J. S. McCasland
  • T. A. Woolsey
Article

Summary

Quantitative studies were made of the distribution of labeled intracortical axons after focal injections of horseradish peroxidase (HRP) into mouse barrel cortex, in vitro. The pattern of labeled fibers was compared to that of labeled cell bodies with respect to the barrel map in layer IV. We analyzed 4 cortices with injections in supragranular layers and centered above a single barrel row. Computer microscope/image analysis routines were used to collect the data and to perform various statistical analyses on them. The distributions of both labeled cells and fibers in layer IV and in the infragranular layers show strong connectional tendencies between barrels representing a whisker row. This result is consistent with single unit recordings from barrel cortex. Fiber labeling is more widespread than cell body labeling in layer IV. In addition, the fibers show a directional bias into the adjacent anterior barrel row (e.g., C → D, D → E). In earlier 2-deoxyglucose (2-DG) studies of behaving animals, the anterior barrel rows were more heavily labeled; inter-row projections are therefore predominantly from less active to more active barrel columns. These data show that labeled fiber distribution differs from the distribution pattern of labeled cell bodies. The findings indicate that integration of information between whisker rows within barrel cortex involves asymmetrical connections within layer IV and infragranular layers.

Key words

Cortical connections Cortical columns Barrel cortex Somatosensory system Computer microscope Mice 

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Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • K. L. Bernardo
    • 1
    • 2
  • J. S. McCasland
    • 1
    • 2
  • T. A. Woolsey
    • 1
    • 2
  1. 1.Department of Neurology and Neurological Surgery, James L. O'Leary Division of Experimental Neurology and Neurological SurgeryWashington University School of MedicineSt. LouisUSA
  2. 2.McDonnell Center for Studies of Higher Brain Function, Washington University School of MedicineSt. LouisUSA
  3. 3.Department of Neurological SurgeryWashington University School of MedicineSt. LouisUSA

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