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Synchiria is a neurological condition in which a stimulus applied to one side of the body is referred to both sides. If, for example, one's left hand is touched, he experiences tactile sensations on both hands. People with intact brains do not experience this, probably because of inhibitory mechanisms which prevent activity in one hemisphere of the brain from crossing over to the other.
This phenomenon is therefore very rare, and has only been reported in a small number of brain-damaged patient........ Read more »
J MEDINA, & B RAPP. (2008) Phantom Tactile Sensations Modulated by Body Position. Current Biology, 18(24), 1937-1942. DOI: 10.1016/j.cub.2008.10.068
Spatial navigation is the process on which we rely to orient ourselves within the environment and to negotiate our way through it. Our ability to do so depends upon cognitive maps, mental representations of the surrounding spaces, which are constructed by the brain and are used by it to calculate one's present location, based on landmarks in the environment and on our movements within it, and to plan future movements.
The term "cognitive map" was first used in a landmark 1948 paper, in wh........ Read more »
T. Solstad, C. N. Boccara, E. Kropff, M.-B. Moser, & E. I. Moser. (2008) Representation of Geometric Borders in the Entorhinal Cortex. Science, 322(5909), 1865-1868. DOI: 10.1126/science.1166466
One of the bigger challenges facing researchers who are developing artificial limbs is to create prostheses that not only act but also feel like real limbs. This is especially true for the hand, which is one of the most sensitive parts of the human body, and although advanced prosthetic hands with fully articulated digits which move independently of one another are now available, they would be far more useful if they provided the user with sensory feedback.
Last year, surgeons from the Rehabili........ Read more »
H. H. Ehrsson, B. Rosen, A. Stockselius, C. Ragno, P. Kohler, & G. Lundborg. (2008) Upper limb amputees can be induced to experience a rubber hand as their own. Brain. DOI: 10.1093/brain/awn297
Recent advances in functional neuroimaging have enabled researchers to predict perceptual experiences with a high degree of accuracy. For example, it is possible to determine whether a subject is looking at a face or some other category of visual stimulus, such as a house. This is possible because because we know that specific regions of the brain respond selectively to one type of stimulus but not another.
These studies have however been limited to small numbers of visual stimuli in specified ........ Read more »
Y MIYAWAKI, H UCHIDA, O YAMASHITA, M SATO, Y MORITO, H TANABE, N SADATO, & Y KAMITANI. (2008) Visual Image Reconstruction from Human Brain Activity using a Combination of Multiscale Local Image Decoders. Neuron, 60(5), 915-929. DOI: 10.1016/j.neuron.2008.11.004
In The Expression of the Emotions in Man and Animals, Charles Darwin noted that facial expressions vary little across cultures. We all recognize that someone whose eyes and mouth are wide open, and whose eyebrows are raised, is afraid. This characteristic expression is a social signal, which warns others of a potential threat and serves as a plea for help. It also enhances our ability to sense potential threats, by increasing the range of vision and enhancing the sense of smell.
R........ Read more »
Joan Y. Chiao1, Tetsuya Iidaka2, Heather L. Gordon, Junpei Nogawa,, & Moshe Bar, Elissa Aminoff , Norihiro Sadato5, and Nalini Ambady. (2008) Cultural Specificity in Amygdala Response to Fear Faces. J. Cog. Neuro, 2167-2174.
Body ownership - the sense that one's body belongs to one's self - is central to self-awareness, and yet is something that most of us take completely for granted. We experience our bodies as being an integral part of ourselves, without ever questioning how we know that our hands belong to us, or how we can distinguish our body from its surroundings.
These issues have long intrigued philosophers and psychologists, but had not been investigated by neuroscientists until recently. Now res........ Read more »
Petkova V.I. . (2008) If I Were You: Perceptual Illusion of Body Swapping. PLoS One, 3(12). DOI: http://dx.plos.org/10.1371/journal.pone.0003832
Petkova V.I. . (2008) If I Were You: Perceptual Illusion of Body Swapping. PLoS One, 3(12). DOI: http://dx.plos.org/10.1371/journal.pone.0003832
Synaesthesia is a neurological condition in which stimuli of one sensory modality evoke experiences in another modality. This is thought to occur as a result of insufficient "pruning" during development, so that most of the pathways connecting parts of the brain mediating the different senses remain in place instead of being eliminated. Consequently, there is too much cross-talk between sensory systems, such that activation of one sensory pathway leads simultaneously to activity in another........ Read more »
The term body image was coined by the great neurologist Henry Head and refers to a mental representation of one's physical appearance. Constructed by the brain from past experience and present sensations, the body image is a fundamental aspect of both self-awareness self-identity, and can be disrupted in many conditions.
Disruption of the body image can have profound physical and psychological effects. For example, body image distortion is implicated in eating disorders such as anorexia nervosa........ Read more »
G MOSELEY, T PARSONS, & C SPENCE. (2008) Visual distortion of a limb modulates the pain and swelling evoked by movement. Current Biology, 18(22). DOI: 10.1016/j.cub.2008.09.031
For most of us, visual perception is crucial for spatial navigation. We rely on vision to find our way around, to position ourselves and localize objects within the surroundings, and to plan our trajectory on the basis of the layout of the environment. Blind people would therefore seem to be at a disadvantage. Unable to rely on vision, they depend instead upon different sorts of cues to form their representations of space. They rely, for example, proprioception, which provides a sense of the loc........ Read more »
M. Fortin, P. Voss, C. Lord, M. Lassonde, J. Pruessner, D. Saint-Amour, C. Rainville, & F. Lepore. (2008) Wayfinding in the blind: larger hippocampal volume and supranormal spatial navigation. Brain, 131(11), 2995-3005. DOI: 10.1093/brain/awn250
Prosopagnosia is a neurological condition characterised by an inability to recognize faces. In the most extreme cases, the prosopagnosic patient cannot even recognize their own face in the mirror or a photograph, and in his 1985 book The Man Who Mistook His Wife For A Hat, the neurologist Oliver Sacks describes the extraordinary case of a farmer who lost the ability to recognize the faces of his cows!
Also known as face blindness, prosopagnosia is associated with damage to specific parts of........ Read more »
Cibu Thomas, Galia Avidan, Kate Humphreys, Kwan-jin Jung, Fuqiang Gao, & Marlene Behrmann. (2008) Reduced structural connectivity in ventral visual cortex in congenital prosopagnosia. Nature Neuroscience. DOI: 10.1038/nn.2224
Optogenetics 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 ........ Read more »
W. J. Alilain, X. Li, K. P. Horn, R. Dhingra, T. E. Dick, S. Herlitze, & J. Silver. (2008) Light-Induced Rescue of Breathing after Spinal Cord Injury. Journal of Neuroscience, 28(46), 11862-11870. DOI: 10.1523/JNEUROSCI.3378-08.2008
It 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 h........ Read more »
Sebastian Jessberger, Stefan Aigner, Gregory D. Clemenson, Nicolas Toni, D. Chichung Lie, Özlem Karalay, Rupert Overall, Gerd Kempermann, & Fred H. Gage. (2008) Cdk5 Regulates Accurate Maturation of Newborn Granule Cells in the Adult Hippocampus. PLoS Biology, 6(11). DOI: 10.1371/journal.pbio.0060272
Every 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........ Read more »
T. Fuchs, D. Maury, F.R. Moore, & V.P. Bingman. (2008) Daytime micro-naps in a nocturnal migrant: an EEG analysis. Biology Letters, -1(-1), -1--1. DOI: 10.1098/rsbl.2008.0405
A 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 exper........ Read more »
M EIRAKU, K WATANABE, M MATSUOTAKASAKI, M KAWADA, S YONEMURA, M MATSUMURA, T WATAYA, A NISHIYAMA, K MUGURUMA, & Y SASAI. (2008) Self-Organized Formation of Polarized Cortical Tissues from ESCs and Its Active Manipulation by Extrinsic Signals. Cell Stem Cell, 3(5), 519-532. DOI: 10.1016/j.stem.2008.09.002
The 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 publis........ Read more »
D WHITNEY, N WURNITSCH, B HONTIVEROS, & E LOUIE. (2008) Perceptual mislocalization of bouncing balls by professional tennis referees. Current Biology, 18(20). DOI: 10.1016/j.cub.2008.08.021
Learning 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, ........ Read more »
Z WANG, J EDWARDS, N RILEY, D PROVANCEJR, R KARCHER, X LI, I DAVISON, M IKEBE, J MERCER, & J KAUER. (2008) Myosin Vb Mobilizes Recycling Endosomes and AMPA Receptors for Postsynaptic Plasticity. Cell, 135(3), 535-548. DOI: 10.1016/j.cell.2008.09.057
The 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 each of these columns respond selectively to bars or edges of a specific orientation moving in a specific direction.
Hubel and Weisel also found tha........ Read more »
Ye Li, Stephen D. Van Hooser, Mark Mazurek, Leonard E. White, & David Fitzpatrick. (2008) Experience with moving visual stimuli drives the early development of cortical direction selectivity. Nature. DOI: 10.1038/nature07417
The 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 Ne........ Read more »
L GARRIDO, F EISNER, C MCGETTIGAN, L STEWART, D SAUTER, J HANLEY, S SCHWEINBERGER, J WARREN, & B DUCHAINE. (2008) Developmental phonagnosia: A selective deficit of vocal identity recognition. Neuropsychologia. DOI: 10.1016/j.neuropsychologia.2008.08.003
Erasing 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 othe........ Read more »
X CAO, H WANG, B MEI, S AN, L YIN, L WANG, & J TSIEN. (2008) Inducible and Selective Erasure of Memories in the Mouse Brain via Chemical-Genetic Manipulation. Neuron, 60(2), 353-366. DOI: 10.1016/j.neuron.2008.08.027
The 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 me........ Read more »
Germán Sumbre, Akira Muto, Herwig Baier, & Mu-ming Poo. (2008) Entrained rhythmic activities of neuronal ensembles as perceptual memory of time interval. Nature. DOI: 10.1038/nature07351
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