Fig. 2.

Ocular dominance distribution of retrogradely labeled cells. Anatomical sections showing the distribution of cells retrogradely labeled with WAHG in a normally sighted (a) and a 2 d strabismic (b) kitten. The large black circles surrounded by white halos on theleft and right sides of each figure are the silver-enhanced injection sites. In sections that had not been silver-intensified, the bulk of the injection was restricted to an area of between 100 and 200 μm, which is much smaller than the region of dark precipitate present after silver intensification. Thebright granular labeling between the two injection sites are gold-labeled cells. In these two examples, two injections were made into each hemisphere. c and d show the distribution of the labeled cells from the sections in aand b (red dots) overlaid on optical maps of ocular dominance. It should be noted that a andb are photomontages of microscope fields that have been scaled and rotated by eye to approximate the computer-assisted alignment of the digitally plotted cells in c andd. In c, the injections, each marked by agray circle enclosing a green +, were targeted to two black regions of the ocular dominance map. Ind, the injections were targeted to white regions of the ocular dominance map. Scale bar: a–d, 1 mm. A quantitative distribution of labeled cells >1 mm from the injection site is shown in e–g. In e, the percentage of labeled cells that lay within ocular dominance domains dominated by the eye that dominates the injection site are graphed for normally sighted (red), 2 d strabismic (green), and 7–14 d strabismic (blue) kittens. This color scheme is maintained inf and g and in Figure3c–e. Error bars in e are SEM. Inf and g, the ocular dominance maps were divided into 10 zones of equal area. f shows the difference in the strength of the intrinsic signal between the two eyes for the pixels in each of the 10 zones. On the y-axis, a value of 0 indicates that pixels were equally driven by each of the two eyes. Values near 1 or −1 indicate that pixels were dominated by the same eye that dominates the injection site, or the other eye, respectively. On the x-axis in f andg, a value of 1 is a black region on the optical map, strongly dominated by the other eye. All injections were treated as if they were made into white regions of the ocular dominance map (10 on the x-axis). Values 6–10, therefore, represent the half of the cortex that is dominated by the eye that dominates the injection site, with 6 being most binocular and 10 being most monocular. Values 1–5, then, represent cortical domains dominated by the other eye. g plots the fraction of labeled cells per unit area in each of the 10 ocular dominance zones. A value of 1 on the y-axis indicates no difference from a random distribution. Values >1 indicate an enrichment of labeled cells per unit area, whereas values <1 indicate an impoverishment of labeled cells relative to a random distribution.