Posts from the ‘Molecular Biology’ Category


Retinal Fireworks

Retinal ganglion cells transmit signals from the rods and cones in the eye to the brain. The retinal ganglion cells shown here have the extraordinary property that their dendrites all point in a single direction. Remarkably, these neurons respond best to objects moving in the direction that the cells “point.”

In this particular image, a mouse retina is seen with “J” retinal ganglion cells marked by the expression of a fluorescent protein. Of course, in real eyes it’s not that simple – the millions of other neurons that these are entangled with are not marked, and thus appear invisible. The image was obtained with a confocal scanning microscope, and pseudocoloured.

Part of the Cell Picture Show’s amazing Brainbow series.


Meet Phineas Gage, more commonly known as neuroscience’s most intriguing case.

On September 18th, 1848, the unfortunate 25-year-old railroad worker was using an iron rod to tamp down blasting powder when it exploded, sending the 43-inch-long, 13-pound cylinder through his left cheek and out the top of his head.

While the accident was certainly ghastly, what baffled scientists was both Gage’s survival, and, even stranger, his profound personality changes following the incident. John Harlow, a doctor who treated the once-affable Gage, wrote that he “could not stick to plans, uttered ‘the grossest profanity’ and showed ‘little deference for his fellows,’” as reported by Smithsonian magazine in 2010. Through the remainder of his life, Gage worked at a stable in New Hampshire and then as a stagecoach driver in Chile before moving to San Francisco. He died there after a series of seizures 12 years after the accident.

Even now, 152 years after Gage’s death, he still remains intriguing to neuroscientists – so intriguing, in fact, that his head is prompting a new wave of research. In a new study, published in the May 16 issue of the journal PLoS One, scientists at UCLA used brain-mapping data from computed tomography (CT) and magnetic resonance imaging (MRI) scans to determine the specific damage inflicted on the neurological “pathways” in Gage’s brain.

“What we found was a significant loss of white matter connecting the left frontal regions and the rest of the brain,” said study co-author Jack Van Horn, an assistant professor of neurology at UCLA. “We suggest that the disruption of the brain’s ‘network’ considerably compromised it [the white matter]. This may have had an even greater impact on Mr. Gage than the damage to the cortex alone in terms of his purported personality change.”

Only about 4% of Gage’s cerebral cortex was directly affected by the rod, the study showed. But more than 10 percent of the white matter was damaged. The white matter is the fatty tissue within the brain that coordinates communication between its different regions.

In addition to helping explain Gage’s deterioration, the study showcases the power of brain mapping – a technology that neurologists believe will lead eventually to an understanding of the links between the brain’s “wiring” and specific mental disorders. Even more intriguingly, the study managed to draw parallels between Gage’s case and several modern neurological traumas, including Alzheimer’s disease.

He may have died in 1860, but I have a feeling that we haven’t seen the last of Phineas Gage – or his ghastly accident’s lasting contributions to modern neuroscience.

For more information on Gage and the study, check out the PopSci article here.

Upper image: A computer-generated 3D rendering of the iron rod through Gage’s brain as estimated from his skull (which is on display at Warren Anatomical Museum in Boston, along with the tamping rod).

Lower Images: Left, a circular representation of cortical anatomy and WM connectivity in a normal 25 to 36-year-old male. Right, the mean connectivity affected by the presence of the tamping iron combined across subjects. (And an estimate of Gage’s neural connectivity).

The things we can do with neuroscience these days is incredible. The possibilities even more so! 

Plus those neuroscientists put out some pretty cool images, and who doesn’t love that?


Rival bacterial colonies create a toxic “no-man’s-land” between them when they come too close to each other.

Image Source: PopSci, originally by Eshel Ben-Jacob.

I’d really be interested in seeing what the effect of adding another rival colony to one of the ends would be. Would a peace sign of buffer zone appear? After a few generations, would they start encroaching on the zone as they established resistance? Bacterial evolution is fun!