In this Article, some of the histological sections displayed in Extended Data Figs. 2b and 7 were mistakenly imaged twice and considered as distinct data points (two image pairs in Extended Data Fig. 2b and five image pairs in Extended Data Fig. 7, highlighted by coloured boxes in Fig. 1 of this Amendment). This error happened because the images in question were taken several days or weeks apart by two distinct investigators; differences in image acquisition and processing led to different image properties, resulting in their misclassification. Returning to the original sections and images, we have now corrected this error by removing one copy of the images that were acquired twice and ascribing the corresponding neurons to their proper oligoclones (see Fig. 1 of this Amendment). As a result, 2 cells (out of 403) in the AP 12→12 condition and 11 cells (out of 716) in the AP 12→15 condition have been removed from the dataset. The significance of all statistical analyses following this correction remains unchanged (see the statistical table and summary of figure changes in the Supplementary Information of this Amendment). The Supplementary Table of this Amendment describes the changes to the original Supplementary Table, in which affected values are highlighted using the same colour code as in Fig. 1 . In sections of the original Methods, some values have changed slightly (the changes to the affected paragraphs are detailed in the Supplementary Information to this Amendment). In addition, the legend of Extended Data Fig. 3b now cites Extended Data Fig. 2 instead of Extended Data Fig. 4 and the legend of Extended Data Fig. 6 now mentions 79 oligoclones (AP 12→15 ) instead of 78. The original Supplementary Table 1 and Extended Data Figs. 2b and 7 of the original Article have been corrected online, in addition to the text changes described above (but not the original figures).

Fig. 1: This figure shows the as-published, incorrect panels of Extended Data Figs. 2b and 7 and the corresponding corrected panels. a, b, In this part of Extended Data Fig. 2b, the sections that were imaged twice (in ‘Donor litter 2’ and in ‘Donor litter 4’) are boxed in blue and brown, respectively (a) and the retained images are boxed (b). c, d, In this part of Extended Data Fig. 7, the five sections that were imaged twice (in ‘Donor litter 6’) are boxed in matching colours (c) and the retained images are boxed (d). Full size image