Neuronal pairs with similar orientation preferences were estimated to have stronger interactions than pairs preferring different stimulus orientations.
In this coordinate system, a voxel at 0° polar angle having a 0° orientation preference is a horizontal-meridian voxel preferring horizontal orientation, and a voxel at 90° polar angle having a −90° or 90° orientation preference is a vertical-meridian voxel preferring vertical orientation; both voxels can be regarded as having radial-angle orientation preferences.
Fig. 1 Layout of orientation preferences in the visual cortex of a tree shrew (modified from Bosking et al. [10]).
Iso-orientation domains form continuous bands or patches around pinwheels and, on average, a region of about 1 mm2 (hypercolumn) will contain all possible orientation preferences.
If z is to produce a quasi-periodic layout of orientation preferences with characteristic distance Λ, this seems to leave no room for systematic correlations at a much longer or much shorter distance than Λ.
In many species including primates and carnivores (but no rodent, even though some of them have rather elaborated vision [4, 5]), these orientation preferences are arranged in an ordered map along the cortical surface.
In other words, it is reasonable to say that monochromatic invariant random fields provide as good a description for the layout of orientation preferences as invariant fields with more realistic spectra do (perhaps even better; see [34]).
These changes in DNA charge had converse effects on the orientation preferences of heterodimers in which charged amino acid residues adjacent to the basic regions were exchanged between Fos and Jun.
The spatial precision of this approach was in the range of 100 μm and experiments in cat primary visual cortex revealed a close correlation between the desired and the actually recorded orientation preferences of the targeted columns.
With this in mind, it seems very striking that the functional architecture of V1 should rely on a structure, the "association field" (see [13], Chap. 4) and its condition of "coaxial alignment" of orientation preferences, which simultaneously uses Euclidean geometry at several of these levels.
(c) How are the orientation preferences for both eyes matched [36]?
