I remember years ago watching a BBC documentary (I think it was BBC) with the tabloid-type title “is your brain really necessary?” it focused on patients with severe hydrocephalus who had normal neurological examinations and normal intellect. One was, if I remember right, a university student, in geography or some-such, who had a cortical mantle thickness of about 1 cm.
A recent article, discussed by Neuroskeptic, has reported some new cases, and made ridiculous claims suggesting that this is evidence that our memories are stored in the cloud and accessed by magic (or some unknown electromagnetic wave particle).
A new case report in the Lancet is of a 62 year old with this MRI, a woman with apparently normal function:
Which just shows again how little correlation there is between images and function, under some circumstances. Another one of those circumstances for example is patients with meningomyelocele:
This very recent article for example looked at young adolescents with meningomyelocele who were all shunted for hydrocephalus. The average IQ was about 1SD below controls. The study showed poor correlation between mantle thickness in most areas and IQ, and no correlation at all in some areas of the brain. This study also looked at gyrification, and at fine motor skills. There are a number of very interesting associations, which confirm that, in general, cerebral development is disturbed in meningomyelocele, and that the more disturbed it is, the more affected are fine motor skills. Some of the associations start to get complicated, but I just wanted to point out that the statistically significant correlations are interesting from a research point of view, but are not all that strong; as in many other situations, we should be very circumspect about making individual predictions of outcome from brain imaging findings.
A child with an antenatal diagnosis of meningomyelocele can have a range of developmental and neurologic challenges, but the degree of hydrocephalus and other findings on ante- or post-natal cerebral imaging do not closely predict their eventual function.