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Uh, two paper reviews so close? ...

Posted Sep 13 2008 3:33pm

_blogmondaymorning.jpg Uh, two paper reviews so close? Good thing there's an abundance of interesting stuff out there. Come to think of it, we could actually run paper reviews every day! Though it would take a lot of time gathering all items, it would certainly be possible. This highlights one of the shortcomings of this (or any) kind of communication: we can only tap into a minor part of all of what's going on. Show the tip of the iceberg, so to speak. Oh well, here goes:

The journal Biological Psychology runs a special issue this month on animal vs. human cognition. Articles include comparisons of hippocampal function, fear conditioning, and the influence of maternal programming on gene expression (!).

In Cognitive Neuropsychology Iftah Biran and colleagues propose a model for understanding alien hand syndrome, in which brain-damaged patients experience their limb performing seemingly purposeful acts without their intention. They suggest a three-factor model: 1) a disinhibited and reactive limb; 2) the limb is under less volitional control; and 3) the person has a relatively intact self-monitoring system. I think that one more level should be added, in between 2 and 3; i.e. 2½) the limb performs automatisms and other unconsciously controlled behaviours.

My story about the new way to use diffusion MRI to measure brain activation really spurred some activity web-wise. We got the number of visitors reaching an all-high with this post. Just a few links here, here, here and here just to mention a few. While at it, we should not forget another promising (and well known) fMRI method, perfusion fMRI (good page here ). While this method still needs to be improved, e.g. in terms of signal intensity, it has the advantage over other methods such as BOLD, and now diffusion, fMRI in that it suffers from less susceptibility artefacts. This is a real advantage if you're studying areas close to air filled areas such as the nasal cavities. Areas such as the orbitofrontal cortex and medial temporal lobe (e.g. amygdala, hippocampus, perirhinal and entorhinal cortex, anterior fusiform gyrus and parahippocampal gyrus) are suffering from distortions during BOLD fMRI paradigms, and will do so using diffusion fMRI, too.

The obvious next step would be to compare all three methods, BOLD, diffusion and perfusion MRI, to get an estimate of the best sequences for different tasks. In addition, it could shed light on the workings of the brain, running all three paradigms on a specific cognitive task. By comparing to BOLD and perfusion fMRI we could learn more about the mechanisms behind diffusion MRI. Hm, maybe my next project?

I thought Martin was going to blog about this story (if he did, sorry for the duplicate): Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology has sequenced the first nuclear DNA from a Neanderthal! A story in Nature covers it nicely. Should this project be successful, we should have plenty of studies comparing human and Neanderthal genes. As such, they are bound to have an impact on the way we understand our own species.

-Thomas

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