For the latest news and information on traumatic brain injury check out hosted by Michael Kaplen, Esq., President of the Brain Injury Association of New York State and a leading advocate for the brain injured. He is a a member of the New York State Traumatic Brain Injury Services Coordinating Council and the past chair of the Association of Trial Lawyers of America Traumatic Brain Injury Litigation Group.

Regular spatial grid mapping found in hippocampus

An area of the hippocampal formation (dMEC, dorsocaudal medial entorhinal cortex) contains neurons which fire when the animal is in a particular location (like hippocampal place cells), but which have a strikingly regular mapping from neurons to locations (that is, the “place field” to which each cell responds is very regular and geometric).

Torkel Hafting, Marianne Fyhn, Sturla Molden, May-Britt Moser and Edvard I. Moser. Microstructure of a spatial map in the entorhinal cortex. Nature, doi: 10.1038/nature03721.

Check out figure 1 from the paper, particularly the two rightmost columns in section (b):

The caption for parts (a) and (b) of this figure is: “a, Sagittal Nissl-stained section indicating the recording location (red dot) in layer II of the dMEC. Red line indicates border to postrhinal cortex. b, Firing fields of three simultaneously recorded cells at the dot in a during 30 min of running in a large circular enclosure. Cell names refer to tetrode (t) and cell (c). Left, trajectory of the rat (black) with superimposed spike locations (red). Middle, colour-coded rate map with the peak rate indicated. Red is maximum, dark blue is zero. Right, spatial autocorrelation for each rate map (see Supplementary Methods). The colour scale is from blue (r = -1) through green (r = 0) to red (r = 1). ”

Geron pursuing ES cells for spinal cord therapy

Looks like spinal cord regeneration might be the first target for embryonic stem cell therapy trials in humans. More info in the Science article.

It looks like Geron has developed a protocol to reliably induce ES cells to become oligodendrocytes, the glial cells that produce the myelin sheath. Here’s the details from the article:

For newly injured rats, the results are promising. In animals that received oligodendrocyte precursors 7 days after their injury, the cells survived and apparently helped repair the spinal cord’s myelin. Within 2 weeks, treated rats scored significantly better on standardized movement tests than control animals, which had received human fibroblasts or a cell-free injection.

Decussation explanation

Neat story in the WaPo on the evolution of decussation (the crossings — mostly in the brainstem — that cause motor/sensory information to be processed in opposite halves of the brain from where the action is).

The article quotes Denis Jabaudon as extending an explanation originally from Ramon y Cajal: That the sensorimotor system is simply following suite with the visual system, which itself reversed right and left in the brain to compensate for the 180 degree inversion of an image on the retina (due to the lens of the eye).

Nasally administered oxytocin causes trusting behavior

Subjects played a game in which “investors” could give money to “trustees”. They could make more money this way, but only if the trustee honored the investor’s trust by sharing the profits equally.

29 investors were given a nasal spray of oxytocin, and 29 weren’t. 13 (45%) of the oxytocin investors invested highly, but only 6 (21%) of the control group did.

“The researchers, led by Dr Ernest Fehr, say this suggests the chemical promotes social interaction, rather than simply encouraging people to take risks.” — BBC

The oxytocin had no effect if the trustee was a computer, instead of a person. Oxytocin had no effect on trustees.

It's all about the connections

This CNN story is a bit off the wall (the title is “Brain downloads ‘possible by 2050′”); it is mostly about how the new PlayStation 3 and other modern supercomputers are approaching the computational power of the brain. From the article:

“The new PlayStation is one percent as powerful as the human brain,” Pearson told the Observer. “It is into supercomputer status compared to 10 years ago. PlayStation 5 will probably be as powerful as the human brain.”
[Pearson is “head of British Telecom’s futurology unit”.]

But is this really an accurate estimate?

We were discussing this story in lab and my advisor came up with this analysis:

PlayStation 3 has 0.3 x 10^9 transistors and runs at 3 x 10^9 Hz.
That works out to 10^18 switching operations per second.

Your brain has 10^15 synapses running at 10^3 Hz.
That also works out to 10^18 elementary operations per second.

So it’s arguable that PlayStation 3 is just as powerful as your brain,
in terms of raw computational power. We just don’t know how to organize
that power properly.