The brain in question belongs to neuroscientist Russ Poldrack, and he’s one of the authors of the paper. Poldrack was fMRI scanned a total of 84 times over a period of 532 days. The goal of this intense scanning schedule was to provide a detailed analysis of the functional connectivity of an individual brain...
On the other hand, to understand an individual brain, one scan is not enough, because “an observed pattern of functional brain organization in an individual may reflect persistent traits shaped by development and genetics, but may also relate to current state or environmental effects.” Hence this study.
So what did they find? One important result was that the degree of session-to-session (within subject) variability in connectivity was higher in some brain regions than in others:
Within-subject variability was non-uniformly distributed across systems, with higher variability observed in correlations within and between somatomotor and visual regions. Relatively less variability was observed between frontoparietal, default mode, ventral attention, and medial parietal regions.It’s notable that while visual cortex connectivity is one of the most variable networks in Poldrack’s brain, it’s one of the most stable across individuals.,,
We don’t know whether this pattern of variability is, itself, invariant across subjects, or whether Poldrack’s visual cortex is just unusually variable.
Laumann et al. performed several other analyses, on Poldrack’s data and also on data from Nico Dosenbach (another of the authors, who was scanned ten times). However, they refrain from reading too much into the results, concluding that
Any study reporting observations in one or two subjects has necessarily limited generality… Therefore, we do not assign specific meaning to the detailed features observed here. However, we believe that the reliable presence of these detailed features in each individual must motivate further studies of this type…Then again, convincing these patients to undergo dozens of MRI scans might be tricky, though, and so would finding money to pay for them.
In particular, we believe that the subject-specific approach outlined here may be essential for understanding the functional brain organization of unique or rare subjects (e.g., cognitive savants, rare disease populations, or brain-injured subjects like H.M.).
Courtesy of: http://www.medpagetoday.com/Neurology/GeneralNeurology/52922?xid=nl_mpt_DHE_2015-08-05&eun=g906366d0r
Laumann TO, Gordon EM, Adeyemo B, Snyder AZ, Joo SJ, Chen MY, Gilmore AW,
McDermott KB, Nelson SM, Dosenbach NU, Schlaggar BL, Mumford JA, Poldrack RA,
Petersen SE. Functional System and Areal Organization of a Highly Sampled
Individual Human Brain. Neuron. 2015 Jul 22. pii: S0896-6273(15)00600-5. doi:
10.1016/j.neuron.2015.06.037. [Epub ahead of print]