Posts from the ‘brain’ Category


All vertebrates’ eyes emerge from a single group of cells, called the eye field, located in the middle of the brain. The eye field cells evaginate to form two optic vesicles, which eventually give rise to two retinas, one on either side of the brain.

Eyes Emerge

Top image: In a ~5 somites embryo, eye field cells are stained red, and forebrain cells are outlined in green (upper left). A few hours later, in a ~10 somites embryo, the eye field (green) separates into two optic vesicles. At the same embryonic stage, the dorsal telencephalon, which sits atop the evaginating eyes, is labeled blue (bottom left). In both of these images, a midline positioned cross outlines the apical surface of the optic vesicles and the ventricular space. The animation follows the development of this same surface as the eyes emerge from the brain.

Sunrise in the Eye

Bottom image: Once the basic shape of the eye is specified, cells within the optic cup differentiate, populating the retina with neurons that sense light and refine the visual information before it is transmitted to the brain. In fish and amphibia, retinal stem cells are maintained throughout the animal’s lifetime in a stem cell niche located adjacent to the lens (yellow). Here in situ hybridization of a zebrafish eye (from a ~ 3-day-old larva) reveals gene expression patterns that distinguish retinal stem cells (red) from the cells that are becoming neurons (purple). By comparing gene expression patterns within the retinal stem cell niche in normal and mutant eyes, we gain insight into how stem cells turn into neurons.

Eyes are not only amazingly complex, but are reducibly so!


The Science of Linguistics

Linguistics is by definition the scientific study of language, but it’s been long debated whether it is a “soft” science. Science is the systematic study of the physical and natural world through observation and experiment, and hard sciences are generally perceived as more rigorous and accurate—i.e., natural, physical and computing sciences. “Soft” sciences are usually social, but linguistics seems to blur the line between the two—language is a social construct, but it’s also a complex, ever-evolving natural phenomenon, made up of dozens of sounds that combine to create thousands of words in thousands of different languages. Linguists study the use of language almost like animal behaviour is studied, and in recent years, modern linguistics has gravitated towards a “hard” science approach, focusing on accuracy, objectivity, and empirical data. Its many specialised subfields help enforce the rigour, such as phonology (the study of sound), syntax (the study of sentences), and semantics (the study of meaning), and linguistics also crosses disciplines to study the psychology, the neuroscience, and even the computer science of languageenabling the creation of language databases to analyse written and spoken patterns. However, hard sciences also have the capability to draw strong conclusions and make accurate predictions, and linguistics often deals with too many non-quantifiable variables to achieve either of these. For now, linguistics remains a soft science—but that doesn’t make it any less fascinating. After all, without language, we wouldn’t be able to communicate scientific ideas at all.

(Image Credit: 1, 2)

I only have some historical background knowledge on linguistics, mostly on how it shows human migrations, but the entire field seems fantastically interesting.


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.


6th Prize – Thomas J. Deerinck

National Center for Microscopy & Imaging Research – University of California – San Diego – La Jolla, California, USA

Specimen: Rat retina astrocytes and blood vessels (160x)
Technique: Fluorescence and Confocal

Astrocytes (yellow) are glial cells in the brain and spinal cord. They are so named for their “star” shape. They are the most abundant types of cell in their cell and give it its physical structure. Among other biochemical and metabolic processes, they are associated with neural synapses that help the brain communicate with itself, and other parts of the body.

(The red and blue stains are blood vessels that supply the area with oxygen and nutrients.)


This is a corrosion cast of the blood vascular system of the human brain. Basically, they fill the blood vessels with a kind of plastic material and then remove the organic tissue, so you can see all the blood vessels without anything else to get in the way. We know that the brain is a huge drain on oxygen and so needs a lot of blood, but I think this is really cool that you can see how well vascularized it really is and how very many blood vessels and capillaries there are in the brain.

[Image Source]


A neuronal kiss

A basket cell kissing a pyramidal cell
from the Blue Brain Project
-by Henry Markram


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?