I do like the idea of splitting up the disparate topics. Personally, living nowhere near any meetup locations, I find those announcements to be a bit spammy.

Might consider making the brain thing more abstract and graphic design-y, something relating to an actual head silhouette like a subway map relates to a geographical map. The region edges that look like they've been drawn in freehand look particularly off to me.

The idea itself might be catchy, but I'd prefer graphic layout suggesting a brain profile drawing rather than a brain profile drawing suggesting a graphic layout.

One small change I would like regards whatever magic runs the recent comments/posts widgets. I recently loaded the site on a work computer (!) that was sufficiently ancient as to not understand any of it, and the site loaded amazingly fast (excepting recent widgets, which were disabled). So I suspect that whatever magic runs it is blocking the site from rendering immediately, as it tends to take a couple seconds on my somewhat-modern-but-still-ancient laptop that runs Chrome.

Of course, I know next to nothing about dynamic webpages, so feel free to ignore this if it's completely misguided.