cajal

Cajal’s histological preparations and drawings showing some contributions to glial cells. (A) Fibrous astrocyte in the white matter of adult brain (formalin-uranium nitrate and gold-sublimated chloride); (B) Protoplasmic astrocyte in an adult brain (silver carbonate (del Rio) and formalin-uranium nitrate); © Twin astrocytes in the human hippocampus (formalin-uranium nitrate); (D) Fibrous astrocytes from the white substance of adult brain (Golgi methods); (E) Olygodendrocytes (ammoniacal silver oxide and Nissl); (F) Microglia cells (ammoniacal silver oxide, reduced silver nitrate and silver carbonate (del Rio) methods).

Source: The Histological Slides and Drawings of Cajal

Drawing of a retinal neuron by Ramón y Cajal, my favourite neuroscientist of all time. This guy was one of the first people to systematically look at cellular brain structures under a microscope and make drawings of them in the late 1800s-early 1900s, and many of his drawing are still used in textbooks today. He was making better histological slides a century ago than I can do now! Plus, he was a bit of an anarchist and went to jail at age 11 for blowing up his town gate with a cannon.

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Got books on the brain? Why not get some books on the brain? (Work it out.)

The 2014 Society for Neuroscience Annual Meeting is taking place November 15-19 in Washington D.C. If you’re attending the meeting, stop by booth 200 to check out these books and more.

Any brainy books to add to the list? 

DO BLACK HOLES HAVE A BACK DOOR?

One of the biggest problems when studying black holes is that the laws of physics as we know them cease to apply in their deepest regions. Large quantities of matter and energy concentrate in an infinitely small space, the gravitational singularity, where space-time curves towards infinity and all matter is destroyed. Or is it?

A recent study by researchers at the Institute of Corpuscular Physics (IFIC, CSIC-UV) in Valencia suggests that matter might in fact survive its foray into these space objects and come out the other side.

Published in the journal Classical and Quantum Gravity, the Valencian physicists propose considering the singularity as if it were an imperfection in the geometric structure of space-time. And by doing so they resolve the problem of the infinite, space-deforming gravitational pull.

“Black holes are a theoretical laboratory for trying out new ideas about gravity,” says Gonzalo Olmo, a Ramón y Cajal grant researcher at the Universitat de València (University of Valencia, UV). Alongside Diego Rubiera, from the University of Lisbon, and Antonio Sánchez, PhD student also at the UV, Olmo’s research sees him analysing black holes using theories besides general relativity (GR).

Specifically, in this work he has applied geometric structures similar to those of a crystal or graphene layer, not typically used to describe black holes, since these geometries better match what happens inside a black hole: “Just as crystals have imperfections in their microscopic structure, the central region of a black hole can be interpreted as an anomaly in space-time, which requires new geometric elements in order to be able to describe them more precisely. We explored all possible options, taking inspiration from facts observed in nature.”

Using these new geometries, the researchers obtained a description of black holes whereby the centre point becomes a very small spherical surface. This surface is interpreted as the existence of a wormhole within the black hole. “Our theory naturally resolves several problems in the interpretation of electrically-charged black holes,” Olmo explains. “In the first instance we resolve the problem of the singularity, since there is a door at the centre of the black hole, the wormhole, through which space and time can continue.”

This study is based on one of the simplest known types of black hole, rotationless and electrically-charged. The wormhole predicted by the equations is smaller than an atomic nucleus, but gets bigger the bigger the charge stored in the black hole. So, a hypothetical traveller entering a black hole of this kind would be stretched to the extreme, or “spaghettified,” and would be able to enter the wormhole. Upon exiting they would be compacted back to their normal size.

Seen from outside, these forces of stretching and compaction would seem infinite, but the traveller himself, living it first-hand, would experience only extremely intense, and not infinite, forces. It is unlikely that the star of Interstellar would survive a journey like this, but the model proposed by IFIC researchers posits that matter would not be lost inside the singularity, but rather would be expelled out the other side through the wormhole at its centre to another region of the universe.

Another problem that this interpretation resolves, according to Olmo, is the need to use exotic energy sources to generate wormholes. In Einstein’s theory of gravity, these “doors” only appear in the presence of matter with unusual properties (a negative energy pressure or density), something which has never been observed. “In our theory, the wormhole appears out of ordinary matter and energy, such as an electric field” (Olmo).

The interest in wormholes for theoretical physics goes beyond generating tunnels or doors in space-time to connect two points in the universe. They would also help explain phenomena such as quantum entanglement or the nature of elementary particles. Thanks to this new interpretation, the existence of these objects could be closer to science than fiction.

Figure 1. Reproduction of an original Cajal drawing from a Golgi stained horizontal section from 20-days-old mice, showing some morphological features of the accessory and main olfactory bulb. (A) Accessory olfactory bulb; (B) Main olfactory bulb; © Cortex; (D) Vomeronasal nerve; (a) Glomerular layer; (b) mitral/tufted layer; © Plane of the lateral olfactory tract; (d) granule cells [Ramon y Cajal (1901)].

Eduardo Martín-López et al. Postnatal characterization of cells in the accessory olfactory bulb of wild type and reeler mice; Front. Neuroanat., 22 May 2012

Okay, here is the last one of my Cajal spam.  Cajal is a legend in anatomy and neuroscience.  You can find him in the first chapter or two of every modern neuroscience, psychobiology, or psychopharmacology textbook.  He taught himself to paint and draw at an early age, but turned to a medicine for a career, although he never lost his artistic passions.  Click here for the full gallery.

“Nature seems unaware of our intellectual need for convenience and unity and very often takes delight in complication and diversity.” From Nobel lecture, 1906

Cajal’s view of astrocytes (A, B, and C), cells that fill many important support roles for neurons (D) in the brain.

The majority of dreams consists of scraps of ideas, unconnected or weirdly assembled, somewhat like an absurd monster without proportions, harmony or reason… The fallow lands of the brain, that is, the cells in which unconscious images are recorded, stay awake and become excited, rejuvenating themselves with the exercise they did behind the back of the conscious mind.
— 

Nautilus uncovers the lost dream journals and dream theories of neuroscience founding father Santiago Ramón y Cajal, who set out to prove Freud wrong.

In the eight decades since his death, scientists have come to understand why we dream and have nightmares

Complement with a marvelous vintage dream book illustrated by Freud’s eccentric niece. 

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The first illustration by Camillo Golgi showing a network of neurons found in the olfactory bulb of a dog. Golgi has invented a method, now called Golgi-stain, which is used to image neurons in different tissues. Golgi-stain is based on reaction between potassium dichromate and silver nitrate, which leads to silver chromate being deposited on cell membranes and giving them dark colour. Only random and relatively few neurons are stained at a time, allowing to distinguish single cells, which are part of dense and complicated neuronal networks. Golgi has described his technique in 1873 and it provided one of the strongest evidence at that time to prove that neurons are the building blocks of the nervous system. Golgi, together with Santiago Ramón y Cajal, was awarded the Nobel Prize in 1906 in recognition of their work on the structure of the nervous system”.

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