Figure 3: Visual imprinting localized the population of cells responsive to the imprinting stimulus.

(a) Experimental design. Chicks were subjected to two sessions of exposure. During the 1st session, chicks were exposed to the black monitor without any image (CT), the moving red square (RT), or the moving blue square (BT). During the 2nd session, chicks were exposed to the moving red (R) or blue square (B). (b) RT–R and BT–B chicks showed significant preference to the 2nd stimulus. Number of chicks used are indicated in each bar. (c). Schema showing the pathway for visual imprinting in the chick telencephalon (left) and Arc expression in the enclosed region of the left schema (right). This photograph is identical to the one presented in Fig. 1b. The rectangular area shows analysed region. (d) An example of Arc expression of CT–R and RT–R chicks in the analysed regions. (e) Schema of the analysed region that was divided into 8 rostral-caudal × 32 dorsal-ventral areas. The percentages of Cyto cells, Nuc cells, and Nuc + Cyto cells to the total number of cells were calculated in each small area. (f) Heat maps were created from the mean value of the calculated percentages of Cyto cells. (g) Percentages of Cyto cells in each of the 8 rostral-caudal rectangular areas are plotted. Numerous Cyto cells are broadly distributed in each condition, except for in CT–R chicks. (h) Heat maps of Nuc cells. (i) Nuc cells are gathered in the rostral area in each condition, except for in CT–R chicks. (j) Heat maps of Nuc + Cyto cells. (k) In RT–R and BT–B chicks, Nuc + Cyto cells are gathered in the rostral area. (l) Venn diagrams and table created similarly as Fig. 2d, for the position 2. (m) Number of cells in the 8 rostral-caudal rectangular areas is shown for each condition. No significant differences were found among positions. *p < 0.05; **and ^##p < 0.01. Scale bar = 250 μm (c) and 100 μm (d).