Figure 1.

Tool use training of Rhesus macaque monkeys (A, B) and collected brain areas for gene expression analysis (C–E). Schematic representation of tool use training (A). Experimental procedure and learning curve of tool use training (B). Horizontal axis indicates learning periods. Vertical axis indicates the score of the tool use test. The score of 50 timed trial tests was calculated as follows: monkeys retrieved pieces of food on the first attempt (score 3), second attempt (score 2), multiple attempts (score 1) or more than five attempts or failed (score 0). Dissection and sample preparation of the macaque brain (C–E). Examples of dissected area from the lateral sulcus (LS) and the intraparietal sulcus (IPS) region (marked area) (D, E). RNAs were purified from the anterior region of the surrounding area of LS including SII and insula (Is), and from the posterior region of the surrounding area of the IPS. We collected both superior and inferior LS and IPS regions, because it was difficult to dissect half of these areas.