Precuneus and chimps

Bruner et al 2016 - Brain Structure and FunctionWe modern humans have larger parietal bones and large parietal lobes when compared with extinct human species and living apes. We also have an ontogenetic parietal bulging stage, a stage which is absent in apes and Neandertals. Interestingly, a main factor of variability in our brain morphology is the size of the precuneus, in terms of proportions and cortical surface area. Now we have compared human and chimp brains, and here it goes again: the main difference is a much larger precuneus in our species. It doesn’t look like an allometric issue, being possibly associated with that bulging stage specific of modern humans, and even absent in large-brained Neandertals. The precuneus is essential in visuospatial integration, coordinating brain, body, and environment, and bridging the somatosensorial experience with simulation and self-awareness. It is a key element to integrate space, time, and  social perception. It is also worth noting that parietal lobes are particularly vascularized in our species, and the precuneus is a high-metabolic and heat-accumulating element. This may be interesting when considering that it suffers early metabolic impairments in Alzheimer’s disease, a pathology particularly associated with our species. The precuneus is also a central hub of the default mode network. Interestingly, at least in adult modern humans the size of the parietal lobes is inversely correlated with the size of the frontal and temporal lobes, introducing some phylogenetic issues on the evolution of the fronto-parietal system.

For a long time we have been looking for subtle differences between human and ape brain. This one looks not that subtle. Any functional or histological change behind this expansion, at inter-specific and intra-specific level, is still to be investigated. But most of all, it remains to be established the nature of such morphological variations. Genetic factors and selective processes cannot be excluded, but these areas are also particularly sensitive to environmental influences, including training and cultural effects.

Advertisements

2 Responses to “Precuneus and chimps”


  1. 1 Evie January 15, 2016 at 23:04

    I’m strongly interested in paleoneurology and, as a student, am wondering what I could do which would help in pursuing this as a career?

  2. 2 emilianobruner January 16, 2016 at 11:31

    Well, in terms of academic career, biology is probably the most direct road. Paleoneurology deals with anatomy, morphology, skulls and brains, integrating all this with information from neuroscience and paleontology. So biology looks the best background needed to begin with.

    However, paleoneurology in the strictest sense may be too “narrow” as discipline, because if one limits the study to fossils and endocasts the information is probably not that much to allow the development of complete and self-sustainable research lines. In my view, paleoneurology is a relevant component of a wider field: evolutionary neuroanatomy.

    For example, we have to take seriously into account that most traits and characters investigated in paleoneurology are not really known even for modern species. We cannot study on few fragmented fossils some complex and complicated features and processes that are not even known for billions of living people!

    Furthermore, the small sample sizes available in paleontology are almost never sufficient to test in quantitative terms a scientific hypothesis. So in general we have to use information form living species to develop a proper theoretical and quantitative framework, and then tests fossils within this framework, as “special case-studies”. Working only with fossils can just give descriptive results, and this can be interesting and important, but not sufficient in science.

    That’s why paleoneurology must be interpreted as a complementary part of something definitely more comprehensive.

    You probably know Springer has recently published this book:
    http://www.springer.com/gp/book/9783319084992

    The University of Colorado has a Center for Cognitive Archaeology with on-line courses, including paleoneurology:
    http://www.uccs.edu/cca/index.html

    Thanks for your interest, Evie, and do not hesitate to ask more!


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s




Enter your email address to follow this blog and receive notifications of new posts by email.

RSS Brain News

RSS Cognitive archaeology

  • DECODING MIMBRES PAINTING
    This extended abstract represents a summary introduction to a work in progress, which will culminate in a publication and exhibition at The Los Angeles County Museum of Art in 2018. It briefly outlines our discoveries and interpretations, which will be more fully presented, referenced and discussed in the forthcoming catalog. This presentation is available f […]

RSS The Skull Box

  • Brain Volume Database
    The Internet Brain Volume Database (IBVD) is an online collection of neuroimaging data funded as a part of the international initiative, the Human Brain Project. The IBVD provides access data for both individual and among-group comparisons that allow total volume comparisons with parallelization of the brain into hemispheres, specific lobes or grey matter vo […]

RSS Anthropology

RSS Human Evolution

  • An error has occurred; the feed is probably down. Try again later.

RSS Neurophilosophy

  • How to become a super memorizer – and what it does to your brain
    New research shows that we can train our brains to become memory champions To many of us, having to memorize a long list of items feels like a chore. But for others, it is more like a sport. Every year, hundreds of these ‘memory athletes’ compete with one another in the World Memory Championships, memorising hundreds of words, numbers, or other pieces of inf […]

Disclaimer

This blog publishes texts and comments of the author, which can not be referred to institutions or contexts outside of the blog itself. The published material may be partly derived or reported from the Web, and therefore evaluated in the public domain. If some content violates copyright or if it is considered inappropriate, please contact me, to promptly remove it. On the other hand, please cite this source whenever using images or texts from this website.

%d bloggers like this: