COMMENTARY. For the article “Confusing cortical columns,” by Pasko Rakic, which appeared in issue 34, August 26, 2008, of Proc Natl Acad Sci USA (105:12099–12100; first published August 20, 2008; 10.1073/pnas.0807271105), the authors note that, due to printer's errors, three references were omitted and a phrase appeared incorrectly. On page 12099, left column, second paragraph, line 11, “(e.g., ref. 2)” should appear as “(e.g., refs. 2, 22, and 23).” Also on page 12099, right column, line 6, “single receptive field” should instead read: “single modalities in the receptive field.” Finally, on page 12100, center column, line 21, “(15, 19)” should appear as “(15, 24)”; and in line 25, “(19–21)” should appear as “(21–24).” In addition to these errors, the authors note that in ref. 3, the author names “Herculano-Housel S, Collins CE, Wang P, Kaas J” should have appeared as “Herculano-Houzel S, Collins CE, Wong P, Kaas JH, Lent R.” The corrected and omitted references appear below.