neuroscience
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…
grrlscientist | November 14, 2008tags: neurobiology, neuroscience, animal communication, birdsong, premotor nucleus HVC, brain temperature, neural circuitry, motor behaviors, bioacoustics
Captive-bred Zebra Finch, Taeniopygia guttata, at
Bodelwyddan Castle Aviary, Denbighshire, Wales.
Image: Adrian Pingstone/Wikipedia [larger view].
Birdsong is the primary model system that helps scientists understand how the brain produces complex sequences of learned behavior, such as playing the piano. In songbirds, there are many interconnected brain regions that play specific and important role in the production of song. These…
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…
purepedantry | November 5, 2008Michael Shermer, editor of Skeptic magazine, has a great article in Scientific American about the limits of interpreting fMRI scanning studies -- particularly how they are presented in the media. The biggest point is that the brain is not a collection of modules isolated from one another; rather, it is a collection of interconnected systems with diverse roles in diverse tasks:
A number of interconnected neural networks may in some cases be localized and bundled into modulelike units, but in most ways they are better described as being splayed out over, under or through the brain's crevasses…
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 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 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…
clock | October 20, 2008You know I have a soft spot for crayfish, so I was excited to read about the new study about their nervous system, nicely explained by Mo:
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 response can mean the difference between life…
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.…
edyong | October 19, 2008
We've all acted impulsively before, and we have the horrendous clothes, echoing bank accounts and hilarious memories to show for it. But science is beginning to show that impulsive people may be particularly vulnerable to drug addiction, and there is little funny or harmless about that.
According to Government statistics, half a million people in the UK are addicted to class A drugs like cocaine, heroin and amphetamines. All too often, drug addiction and other compulsive disorders like obesity are dismissed as issues of 'willpower' and those who succumb to temptation are labelled as '…
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…
purepedantry | October 15, 2008The scientific process is composed of generating hypotheses and testing those hypotheses through experiment. Yet we don't know a whole lot about how about hypothesis generation happens on the level of the brain.
Recognizing that I am dealing with a loaded term -- scientists have strong opinions on the meaning of the term hypothesis -- I would like to talk about a study that looked hypothesis generation in the brain. Kwon et al. used fMRI to look at the brain activation associated with hypothesis generation (as opposed to being just told a hypothesis), with and without training.
Before…
clock | October 14, 2008Or so says this BBC article:
A University of California Los Angeles team found searching the web stimulates centres in the brain that control decision-making and complex reasoning. The researchers say this might even help to counter-act the age-related physiological changes that cause the brain to slow down.