Bregma standard?

Technical
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Hello,
I am trying to determine how to best replicate the stereotactic coordinates used in the connectivity atlas. It seems there are a number of different ways that Bregma can be defined and many publications do not report how they define it leading to replication issues. (See here: Where do you measure the Bregma for rodent stereotaxic surgery? - PubMed ) So, how was bregma defined for connectivity atlas coordinates? In the connectivity atlas, is DV measured from the skull surface or from the dura surface?

And in addition, what strategies do you recommend for accurate targeting of difficult deep/lateral brain structures?

It seems these are very basic, but also very critical issues in the field that are not often discussed and may not have any consensus answers, but it would be extremely helpful to hear guidance on from Allen.
Thanks!

2

Hi,

Thank you for your questions.
Below are answers from one of our scientific technical expert team members.

Thank you.

  1. How was bregma defined for connectivity atlas coordinates. The Bregma as zero point was defined by the intersection with the midline suture.

  2. In the connectivity atlas, is DV measured from the skull surface or from the dura surface? In the connectivity atlas, DV was measured from the dura surface.

  3. What strategies do you recommend for accurate targeting of difficult deep/lateral brain structures? If you target lateral cortical areas, we suggest that you do injections perpendicularly to the dura surface. By doing this way, you can reduce contamination of nearby cortical areas. If you target deep subcortical structures, we suggest using a smaller tip micropipette to avoid leakage along the injection track.