Fetal stem cells rescue cortex after stroke

Amazing results. I hope this serves as a wake-up call to those who still haven’t realized the incredible advances that are being made possible through the use of embryonic stem cells. From the July 27, 2004 issue of PNAS:

Transplanted human fetal neural stem cells survive, migrate, and differentiate in ischemic rat cerebral cortex
S. Kelly, T. M. Bliss, A. K. Shah, G. H. Sun, M. Ma, W. C. Foo, J. Masel, M. A. Yenari, I. L. Weissman, N. Uchida, T. Palmer and G. K. Steinberg

Full article

We characterize the survival, migration, and differentiation of human neurospheres derived from CNS stem cells transplanted into the ischemic cortex of rats 7 days after distal middle cerebral artery occlusion. Transplanted neurospheres survived robustly in naive and ischemic brains 4 wk posttransplant. Survival was influenced by proximity of the graft to the stroke lesion and was negatively correlated with the number of IB4-positive inflammatory cells. Targeted migration of the human cells was seen in ischemic animals, with many human cells migrating long distances ({approx}1.2 mm) predominantly toward the lesion; in naive rats, cells migrated radially from the injection site in smaller number and over shorter distances (0.2 mm). The majority of migrating cells in ischemic rats had a neuronal phenotype. Migrating cells between the graft and the lesion expressed the neuroblast marker doublecortin, whereas human cells at the lesion border expressed the immature neuronal marker {beta}-tubulin, although a small percentage of cells at the lesion border also expressed glial fibrillary acid protein (GFAP). Thus, transplanted human CNS (hCNS)-derived neurospheres survived robustly in naive and ischemic brains, and the microenvironment influenced their migration and fate.

DNA and Molecular Computation

almost offtopic, but neat; here’s a course on “DNA and Molecular Computation”, with a list of papers such as “Chemical Kinetics is Turing Universal”. I didn’t know so much work had been done on this stuff already! cool!


(btw, if you’re interested in reading one of the actual articles, here’s Chemical implementation of finite-state machines, which goes into more (computational) detail than “Chemical Kinetics is Turing Universal” actually does).

Basic number abilities require suitable language?

In what would seem to be a sudden, surprise counterattack by the Whorfian hypothesis, a tribe of otherwise smart people have been discovered whose language doesn’t have words for specific numbers, and where the people have major trouble with the idea of specific numbers of things (even when taught & when trying very hard). The children of the tribe can pick up numbers easily, but the adults don’t.

Constance Holden. Life Without Numbers in the Amazon. Science 2004; 305 (5687) : 1093a (in News of the Week)

More information is in this CNN article.

Probabilistic classification and the basal ganglia

A supervised learning task with a probabilistic relationship between cues and correct response was shown to be impaired in Parkinson’s patients, but not in hippocampal amnesiacs.

This shows a double dissociation between declarative memory and probabilistic classification (i.e. there are two separate learning systems), and shows that the basal ganglia are somehow involved in probabalistic classification.

See NeuroWiki:ProbabilisticClassificationLearning for details and links.

Neuromarketing comes of age

Seems like applied neuroscience has reached another milestone: A company called BrightHouse in Atlanta is already selling neuroimaging-based consulting services for marketing and has apparently been doing so since 2001. Of course, as is often the case with fMRI and other imaging studies, the proof is in the interpretation and it’s debatable how much insight a company can gain from seeing some prefrontal activation with their products.

Here’s a recent New Scientist article on this new area:
They know what you want
New Scientist vol 183 issue 2458 – 31 July 2004, page 36
If neuromarketers can find the key to our consumer desires, will they
be able to manipulate what we buy, asks Emily Singer

WHY DO people who prefer the taste of Pepsi faithfully buy Coke? Will
the Catwoman movie trailer make you want to see the film? And are women
subconsciously drawn to the sight of a bikini-clad model hawking beer
on television?
Continue reading

Phase coding & working memory

Q: How can you very simply implement sequence storage, readout, and comparison using firing phase (rather than firing rate) as your neural code?

Q: Why does working memory hold 7 +- 2 items?

Q: Why is possibly transient phase-locking observed between the hippocampus and the entorhinal cortex, the cingulate cortex, and the prefrontal cortex?

Q: Why do the phases of place cells in the hippocampus (relative to the theta rhythm) precess as a rat moves further into the cell’s place field?

Read on for all this and more!
Continue reading

Bayesian Brain course in Okinawa, Nov 9-19th

Call for Applications
November 9-19, 2004. Okinawa, Japan.

The special topic for this year’s course is “Bayesian Brain: Probabilistic
Approaches to Neural Coding and Learning.” Lectures by leading theoretical
and experimental neuroscientists will be given in the morning and evening,
and the afternoon will be open for free discussions and student projects.
Continue reading

State of the art for depression

This month’s Nature Neuroscience includes an interesting editorial on what might really be happening with monoamine-targeted antidepressenants (ie. like SSRIs). The article suggests that downstream effects might be the actual regulators of emotional mood; for example, serotonin is known to both increase neurotrophin production and induce neurogenesis.

Full article is here.