title: Vertical meridian representation on the prelunate gyrus in area V4 of macaque.
abstract: The representation of the lower quadrant in area V4 is presently thought to extend along the prelunate gyrus from a foveal representation laterally all the way to the dorsal end of the superior temporal sulcus. However, several studies suggest the possibility of a more complex organization. To see if the visuotopic organization on the crown of the gyrus was relatively homogeneous or instead contained inhomogeneities indicative of more complex organization, we recorded from a grid of points over the prelunate gyrus. Receptive-field size and scatter in the region are large, making it difficult to infer topography from simple inspection of receptive-field sequences. We developed an averaging procedure using data from all recording sites to detect an inhomogeneity in topography with respect to the vertical meridian. With this procedure, we found a vertical meridian representation just medial to the medial end of the lateral sulcus. We also found a significant difference in the incidence of orientation sensitivity on either side of the meridian representation. The results show that the crown of the prelunate gyrus cannot be described as a single homogeneous region, but instead contains at least two different sub-regions adjoining along a shared representation of the vertical meridian.
authors.affiliation: Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14214, USA.
authors.forename: M
authors.initials: M
authors.lastname: Youakim
authors.forename: D B
authors.initials: DB
authors.lastname: Bender
authors.forename: J S
authors.initials: JS
authors.lastname: Baizer
mesh_terms: D000818:Animals; D001931:Brain Mapping; D003118:Color Perception / Q000502:physiology; D005074:Evoked Potentials, Visual / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D008254:Macaca nemestrina / Q000033:anatomy & histology / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D009949:Orientation / Q000502:physiology; D010775:Photic Stimulation; D014793:Visual Cortex / Q000166:cytology / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*