Iso- and cross-oriented columns in cat striate cortex: a study with simultaneous single- and multi-unit recordings.
The constancy of orientation tuning in vertical columns of the visual cortex of the cat was examined with conventional and newly developed multi-electrode methods. Preferred orientation was measured with single- and multi-unit recordings in 68 penetrations approximately perpendicular to the cortical layers and with inter-recording steps of only 40-70 microns. The tuning curves obtained revealed three types of penetration sequences: no-shift penetrations (37%), one-shift penetrations (41%) and double-shift penetrations (22%). Particular attention was paid to the orientation tuning at the transition zones below layer IV. The use of the multi-unit recording technique enabled the measurement of cross-oriented activity within a single electrode position mostly around the border between layers IV and V. Altering the type of anaesthesia (ventilation with room air or nitrous oxide-oxygen) produced only a quantitative change in the percentage of the encountered penetration types. The results suggest that upper and lower layers follow different principles of functional organization. As a consequence different types of columns, especially iso- and cross-oriented ones, are produced in a systematic way.
Philipps-University, Department of Applied Physics and Biophysics, Marburg, F.R.G.
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R
Bauer
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Eckhorn
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Jordan
D000818:Animals; D002415:Cats; D005074:Evoked Potentials, Visual; D005556:Form Perception / Q000502:physiology*; D009039:Motion Perception / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D014793:Visual Cortex / Q000502:physiology*