title: Spatial frequency-dependent feedback of visual cortical area 21a modulating functional orientation column maps in areas 17 and 18 of the cat.
abstract: The feedback effect of activity of area 21a on orientation maps of areas 17 and 18 was investigated in cats using intrinsic signal optical imaging. A spatial frequency-dependent decrease in response amplitude of orientation maps to grating stimuli was observed in areas 17 and 18 when area 21a was inactivated by local injection of GABA, or by a lesion induced by liquid nitrogen freezing. The decrease in response amplitude of orientation maps of areas 17 and 18 after the area 21a inactivation paralleled the normal response without the inactivation. Application in area 21a of bicuculline, a GABAa receptor antagonist caused an increase in response amplitude of orientation maps of area 17. The results indicate a positive feedback from high-order visual cortical area 21a to lower-order areas underlying a spatial frequency-dependent mechanism.
authors.affiliation: Vision Research Laboratory and Liren Laboratory, Center for Brain Science Research, School of Life Sciences, Fudan University, Shanghai 200433, PR China.
authors.forename: Luoxiu
authors.initials: L
authors.lastname: Huang
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.forename: Tiande
authors.initials: T
authors.lastname: Shou
mesh_terms: D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D001931:Brain Mapping; D002415:Cats; D005246:Feedback / Q000502:physiology; D018756:GABA Antagonists / Q000494:pharmacology; D021621:Imaging, Three-Dimensional; D008845:Microinjections; D009434:Neural Pathways / Q000502:physiology*; D010775:Photic Stimulation; D014793:Visual Cortex / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
chemical_list: D018756:GABA Antagonists; D005680:gamma-Aminobutyric Acid; D001640:Bicuculline