neurophilosophy | November 19, 2008
Fox 10 News has a rather gruesome story about the removal of a live parasitic worm from a woman's brain, which is accompanied by a film clip containing footage of the surgical procedure.
As the film explains, the woman, who lives in Arizona, first started to experience flu-like symptoms, followed by numbness in her left arm which grew progressively worse. Neurosurgeon Peter Nakaji operated, expecting to find a tumour in the brainstem, but instead found and removed a tapeworm.
It goes on to say that the woman was infected either by eating uncooked pork or unwashed food contaminated…
neurophilosophy | November 19, 2008
This beautiful image of the brain of a 5-day-old zebrafish larva, which was created by Albert Pan of Harvard University, has just won 4th place in the 2008 Olympus BioScapes Digital Imaging competition. (See a larger version here.)
It was created using the Brainbow technique, a genetic method for labelling neurons, with which individual cells can be made to express a random combination of fluorescent proteins. An image of a mouse brainstem labelled using the same method was awarded 1st prize in last year's competition.
neurophilosophy | November 19, 2008Last Thursday's episode of the Radio 4 programme In Our Time featured a very interesting discussion about recent developments in neuroscience research. Presenter Melvynn Bragg was joined by psychologist Martin Conway of Leeds University, cognitive neuroscientist Gemma Calvert of the University of Warwick and philosopher David Papineau of Imperial College, who talked about the concept of the grandmother cell, new findings which show that the brain makes decisions before we are consciously aware of them, and the relationship between mind and brain. (Download MP3, 20Mb; thanks Ross!)
The most…
neurophilosophy | November 18, 2008Optogenetics is a recently developed technique based on microbial proteins called channelrhodopsins (ChRs), which render neurons sensitive to light when inserted into them, thus enabling researchers to manipulate the activity of the cells using laser pulses.
Although still very new - the first ChR protein was isolated from a species of green algae in 2002 - optogenetics has already proven to be extremely powerful - it can be used to switch neurons on or off in an extremely precise manner and so to control simple behaviours in small organisms such as the nematode worm.
Earlier this year…
neurophilosophy | November 14, 2008
The current issue of Nature contains an interesting article about Sir Christopher Wren's contribution to neuroanatomy, by art historians Martin Kemp and Nathan Flis of Oxford University.
The article focuses on the anatomical illustrations produced by Wren for Thomas Willis's 1664 book Cerebri Anatome (The Anatomy of the Brain). This was a landmark publication in the history of neurology, not least because of Wren's detailed and accurate figures, which were among the very first modern images of brain anatomy. Even so, this aspect of Wren's work was overshadowed by his architectural designs,…
neurophilosophy | November 12, 2008It is now well established that the adult mammalian brain - including that of humans - contains at least two discrete populations of neural stem cells which continue to generate new nerve cells throughout life. These newborn neurons are quickly integrated into existing circuits and are essential for proper functioning of the brain.
A new study published in the open access journal PLoS Biology shows that inhibiting a protein called cdk5 impairs the migration of newly generated neurons into the hippocampus, and causes them to form inappropriate connections with pre-existing cells. The…
neurophilosophy | November 11, 2008Every autumn, millions of songbirds embark upon long distance southerly migrations to warmer climes. Some species migrate during the day, but the majority - including sparrows, thrushes and warblers - do so at night, leaving their daytime habitats just after dusk and spending the next 8-10 hours on the wing.
Nocturnal migration has several benefits. Cooler temperatures reduce the risk of overheating; reduced turbulence allows for a smooth flight with minimal energy expenditure; and the cover of night provides good protection from predators. These fly-by-night migratory species lose…
neurophilosophy | November 11, 2008My first contribution to the Scientific American Mind Matters website is now online. The article, called "The Power of the Memory Molecule", is about the recent study which showed that memories can be selectively erased from the brains of mice by altering levels of the enzyme αCaMKII.
neurophilosophy | November 10, 2008A team of Japanese researchers has demonstrated that embryonic stem cells obtained from mice and humans can spontaneously organize themselves into cortical tissues when grown in a culture dish under special conditions.
Reporting in the journal Cell Stem Cell, the researchers show that the neurons generated form functioning short-range and long-range connections, and can be effectively integrated into existing neuronal circuits following transplantation into the brains of experimental animals.
Yoshiki Sasai, head of the Organogenesis and Neurogenesis Group at RIKEN's Center for…
neurophilosophy | November 4, 2008The Men's Final of the 1981 Wimbledon Tennis Championships is one of the most memorable events in sporting history. John McEnroe, who was playing against Bjorn Borg, famously challenged one of the referee's calls by throwing a tantrum, during which he shouted the immortal line "You cannot be serious!"
McEnroe's outburst was controversial, and he was almost eliminated from the championship because of it. But he may have been right to challenge the referee after all: according to a new study published in Current Biology, in such close calls, professional tennis referees consistently misjudge…
neurophilosophy | November 3, 2008
Yesterday's episode of the CBS programme 60 Minutes featured this report called Brain Power, about the use of brain-computer interfaces (BCIs) by a number of patients who have been paralysed by various conditions. (The 12-minute report is preceded by a commercial.)
Generally speaking, BCIs record the electrical activity of the pre-motor or motor cortex, which are involved respectively in planning and executing movements. The activity is decoded by a computer which then translates it into commands that can be used to control an external device.
The report begins with the case of Scott…
neurophilosophy | November 3, 2008Learning and memory are widely thought to involve long-term potentiation (LTP), a form of synaptic plasticity in which a neuron's response to the chemical signals it receives is enhanced. This leads to a strengthening of the neuronal circuit, so that the memory encoded in the circuit can persist for long periods of time.
One of the mechanisms by which this synaptic strengthening occurs is an increase in the density of receptors in the membrane of the neuron receiving the signals. This process, which involves trafficking of receptors within cells, is implicated not only in learning and…
neurophilosophy | October 31, 2008
Netsuke are miniature Japanese sculptures which are most often carved from ivory or wood, and sometimes from other materials. They were first made in the early 17th century, and used to fasten a small box (the inro) containing medicines and personal belongings to the sash (or obi) worn around traditional Japanese garments such as the kimono. Later on they were made solely for ornamental purposes.
The ivory skull and wooden mask netsuke shown in the photograph above are on display at the Victoria and Albert Museum in London, which has a very nice collection of these delightful objects.…
neurophilosophy | October 28, 2008The pioneering experiments performed by Hubel and Weisel in the late 1950s and early 60s taught us much about the development of the visual system. We now know, for example, that neurons in the visual cortex are organized into alternating ocular dominance columns which receive inputs from either the left or right eye and that groups of cells within these columns respond selectively to bars or edges of a specific orientation moving in a specific direction.
Hubel and Weisel also found that the proper development of these areas of the brain is dependent upon visual information from the eyes.…
neurophilosophy | October 27, 2008The term phonagnosia refers to an inablity to recognize familiar voices or to discriminate between unfamiliar ones. This is a rare condition that is usually associated with brain damage: the ability to recognize familiar voices is impaired by damage to several regions of the right parietal lobe, and impaired voice discrimination is associated with damage to the temporal lobe in both hemispheres.
Researchers from UCL now report the first known case of developmental phonagnosia. In the journal Neuropsychologia, they document the case of a 60-year-old woman known as K.H., who says that she…
neurophilosophy | October 25, 2008
Artist Madeline von Foerster provides some insight into her extraordinary self portrait (above), in a comment posted on my article about trepanation:
During a previous period of depression in my life, I often experienced a severe sensation of pressure in my cranium. It sometimes felt so unbearable I wished I had a hole in my head! A friend told me, "Maybe you just need to be trepannated!" It was a revelation to discover that this surgery existed and was used therapeutically for centuries. My depression later abated and I never pursued that treatment, but my interest continued and I was…
neurophilosophy | October 24, 2008Erasing memories has long been a popular plot device for Hollywood scriptwriters. In the 2004 film Eternal Sunshine of the Spotless Mind, for example, Jim Carrey and Kate Winslet play a separated couple who undergo a radical treatment in order to abolish every trace of the relationship from their brains.
The ability to erase memories is no longer confined to the realms of science fiction. In the current issue of Neuron, researchers from the Medical College of Georgia, in collaboration with others from the Shanghai Institute of Brain Functional Genomics, report that they have rapidly erased…
neurophilosophy | October 22, 2008The fourth dimension - time - is essential for many cognitive processes, and for rhythmic movements such as walking. Recent research has begun to elucidate how neuronal activity encodes events that occur on the timescale of tens to hundredths of milliseconds (hundredths of a second) and contain cues which are required for processes such as visual perception, speech discrimination and fine movements.
Many organisms time events on much larger scales. However, next to nothing is known about the mechanisms by which the brain encodes longer periods of time. A new study now sheds some light on…
neurophilosophy | October 20, 2008
When confronted with threatening stimuli and predators, the crayfish responds with an innate escape machanism called the startle reflex. Also known as tailflipping, this stereotyped behaviour involves rapid flexions of the abdominal muscles which produce powerful swimming strokes that thrust the small crustacean through the water and away from danger. In the struggle for existence, the speed of this response can mean the difference between life and death, and the crayfish has evolved an incredibly fast escape mechanism which can be initiated within well under one-hundredth of a second.…
neurophilosophy | October 16, 2008Researchers from the University of Washington have demonstrated that paralysed monkeys can move using a simple neuroprosthesis consisting of an external electrical circuit which connects individual neurons in the motor cortex to muscles in the arm.
Similar prostheses have been used to move external devices such as a robotic arm, but they required sophisticated algorithms to decode the brain activity associated with generating movements. The researchers adopted the alternative strategy of creating an artificial connection by which the activity of single cells could directly stimulate the…