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Neurophilosophy
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- October 20, 2008
- 02:40 PM
- 3,047 views
The staggering beauty of biology
by Mo in Neurophilosophy
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 and death, and the crayfish has evolved an incredibly fast escape mechanism which can be initiated within well under one-hundredth of a second.
This reflex depends on a process called coincidence detection, whereby the electrical impulses inputs from different parts of the sensory organs arrive simultaneously in the nervous system. Although this reflex has been studied intensively, the mechanism by which nervous impulses arrive in synchrony at the central nervous system was poorly understood. DeForest Mellon, Jr. and Kate Christison-Lagay of the University of Virginia now describe the simple yet ingenious and beautiful mechanism underlying this phenomenon.
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D. Mellon, & K. Christison-Lagay. (2008) A mechanism for neuronal coincidence revealed in the crayfish antennule. Proceedings of the National Academy of Sciences, 105(38), 14626-14631. DOI: 10.1073/pnas.0804385105
- April 3, 2009
- 02:11 PM
- 1,963 views
New cells in the adult brain migrate long distances by crawling along blood vessels
by Mo in Neurophilosophy
The journey undertaken by newly generated neurons in the adult brain is like the cellular equivalent of the arduous upstream migration of salmon returning to the rivers in which they were hatched. Soon after they are born in the subventricular zone near the back of the brain, these cells migrate to the front-most tip of of the olfactory bulb. This is the furthest point from their birth place, and they traverse two-thirds of the length of the brain to get there.
The first leg of this epic journey - the departure of the newborn cells from the subventricular zone - involves some of the signalling cues that guide cell migrations during development of the brain. However, these signals alone are known to be insufficient, and until now the precise mechanisms governing this migration were unclear. But a new study by Canadian researchers shows that the cells travel such long distances by crawling along the capillaries in the olfactory bulb.
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Snapyan, M., Lemasson, M., Brill, M., Blais, M., Massouh, M., Ninkovic, J., Gravel, C., Berthod, F., Gotz, M., Barker, P.... (2009) Vasculature Guides Migrating Neuronal Precursors in the Adult Mammalian Forebrain via Brain-Derived Neurotrophic Factor Signaling. Journal of Neuroscience, 29(13), 4172-4188. DOI: 10.1523/JNEUROSCI.4956-08.2009
- October 2, 2009
- 11:15 AM
- 1,869 views
Circadian and social cues regulate sodium channel trafficking in electric fish
by Mo in Neurophilosophy
SEVERAL hundred species of fish have evolved the ability to generate electric fields, which they use to navigate, communicate and home in on prey. But this ability comes at a cost - the electric field is generated continuously throughout life, so consumes a great deal of energy, and it can also attract predators which are sensitive to it. Electrogenic fish species therefore utilize various strategies to save energy and to minimize the likelihood of being detected. Some generate irregular pulses of electrical discharges whose rate can be modulated; others can also modulate the strength of the electric field.
A beautiful study published in the open access journal PLoS Biology now reveals the cellular and molecular mechanisms underlying one of these behavioural adaptations. It shows that in one species of electric fish, circadian cues and social encounters regulate the movements of proteins called voltage-gated sodium channels - which are crucial for generating the electric field - in cells of the electric organ. At night, low light levels and social interactions drive the insertion of sodium channels into the cell membranes, leading to a dramatic increase in the strength of the electric field.
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Markham, M., McAnelly, M., Stoddard, P., & Zakon, H. (2009) Circadian and Social Cues Regulate Ion Channel Trafficking. PLoS Biology, 7(9). DOI: 10.1371/journal.pbio.1000203
- January 9, 2009
- 09:26 AM
- 1,820 views
The harmonic duets of mosquitoes in love
by Mo in Neurophilosophy
The familiar buzzing sound made by a mosquito may be irritating to us humans, but it is an important mating signal. The sound, produced by the beats of the insect's wings, has a characteristic frequency called the "flight tone"; when produced by a female, it signals her presence to nearby males, thereby attracting potential mates.
Attraction is not simply a matter of the male hearing and homing in on the female's flight tone. Females were long believed to be deaf, but two years ago, it was found that courting pairs interact acoustically to create a duet: both male and female modulate the frequency of their wing beats until their flight tones are closely matched, and this process is fundamental to sexual recognition.
In today's issue of Science, researchers from Cornell University report that the hearing organ of one mosquito species is far more sensitive than was previously thought, and that the courtship duet of this species has a frequency to which the insects were believed to be deaf. Another surprising finding they made about the insects' mating behaviour may also provide a means of controlling mosquito populations. Read the rest of this post... | Read the comments on this post...... Read more »
L. J. Cator, B. J. Arthur, L. C. Harrington, & R. R. Hoy. (2009) Harmonic Convergence in the Love Songs of the Dengue Vector Mosquito. Science. DOI: 10.1126/science.1166541
- March 3, 2009
- 04:24 PM
- 1,751 views
Anatomy of a 300 million year-old brain
by Mo in Neurophilosophy
Nervous tissue is extremely fragile, and so is very well protected. The brain, which has a jelly-like consistency, is encased in the skull, and is surrounded by cerebrospinal fluid, which acts to cushion it against blows that might cause it to come into contact with the inside of its bony case. Likewise, the spinal cord is surrounded by the vertebrae, the series of bones which runs down from the base of the skull.
Being so soft, the brain and spinal cord decompose quickly. When an animal dies, the nervous system begins to disintegrate immediately, until the armour in which it was enveloped is all that remains. Thus, the organ is rarely, if ever, preserved, and brain fossilization is considered to be impossible - or so it was thought.
Now though, a team of French and American researchers report that they have found what appears to be an intact brain in a fossil specimen of Sibyrhynchus denisoni (above), a long extinct relative of the shark and ratfish which lived some 300 million years ago. Their findings are published online this week in Proceedings of the National Academy of Sciences.
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Pradel, A. et al. (2009) Skull and brain of a 300-million-year-old chimaeroid fish revealed by synchrotron holotomography. Proc. Nat. Acad. Sci.
Pradel, A. et al. (2009) Skull and brain of a 300-million-year-old chimaeroid fish revealed by synchrotron holotomography. Proc. Nat. Acad. Sci.
- December 30, 2008
- 10:40 AM
- 1,698 views
Monkeys categorize objects in the same way as humans
by Mo in Neurophilosophy
Being so closely related to our own species, monkeys serve as important model organisms, and have provided many insights into the workings of the human brain. Research performed on monkeys in the past 30 years or so has, for example, been invaluable in the development of brain-machine interfaces.
Monkeys have also contributed a great deal to our understanding of the visual system - they were the subjects in many of the classic experiments of Hubel and Wiesel, which showed that the primary visual cortex contains neurons that are responsive to edges and bars moving in specific orientations.
Yet, little is known about higher order visual processing in the monkey brain. For example, do monkeys categorize objects in the same way as we do? A new study by an international team of researchers addresses this question, and shows that the brains of monkeys and humans do indeed use a common code for categorizing objects in a hierarchical manner.
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N KRIEGESKORTE, M MUR, D RUFF, R KIANI, J BODURKA, H ESTEKY, K TANAKA, & P BANDETTINI. (2008) Matching Categorical Object Representations in Inferior Temporal Cortex of Man and Monkey. Neuron, 60(6), 1126-1141. DOI: 10.1016/j.neuron.2008.10.043
- January 20, 2009
- 12:52 PM
- 1,633 views
The delusional brain
by Mo in Neurophilosophy
Delusions are pathological beliefs which persist despite clear evidence that they are actually false. They can vary widely in content, but are always characterized by the absolute certainty with which they are held. Such beliefs reflect an abnormality of thought processes; they are often bizarre and completely unrelated to conventional cultural or religious belief systems, or to the level of intelligence of the person suffering from them.
The delusions experienced by psychiatric patients are sometimes categorized according to their theme. For example, schizophrenics often suffer from delusions of control (the belief that an external force is controlling their thoughts or actions), delusions of grandeur (the belief that they are a famous rock star or historical figure) or delusions of persecution (the belief that they are being followed, attacked or conspired against).
Although often associated with psychiatric disorders, delusions can also occur as a symptom of neurodegenerative disorders, and improved diagnostic methods have led to an increase in the identification of brain damage in patients who suffer from them. To date, however, there has not been an all-encompassing theory of how the brain generates delusions. Now though, Orrin Devinsky, a professor of neurology, neurosurgery and psychiatry at New York University, proposes that delusions are generated by a combination of right hemisphere damage and left hemisphere hyperactivity.
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O. Devinsky. (2009) Delusional misidentifications and duplications: Right brain lesions, left brain delusions. Neurology, 72(1), 80-87. DOI: 10.1212/01.wnl.0000338625.47892.74
- January 19, 2009
- 12:08 PM
- 1,609 views
Cellular "tug-of-war" breaks brain symmetry
by Mo in Neurophilosophy
The brains of vertebrates are asymmetrical, both structurally and functionally. This asymmetry is believed to increase the efficiency of information processing - one hemisphere is specialized to perform certain functions, so the opposite is left free to perform others. In the human brain, for example, the left hemisphere is specialized for speech. This has been known since the 1860s, when the French physician Paul Broca noted that the aphasia (or inability to speak) which is a common symptom of stroke is associated with damage to a discrete region of the left frontal lobe.
Very little is known about how such asymmetries develop. But now researchers from UCL report that a small population of premature neurons in the developing zebrafish brain is actively pulled from one side of the brain to the other. This cellular "tug-of-war" breaks the anatomical symmetry of the embryonic nervous system, so that cells initially located on both sides end up in a left-sided structure. The findings, which are published in the journal Neuron, shed some light on the evolution of handedness.
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J REGAN, M CONCHA, M ROUSSIGNE, C RUSSELL, & S WILSON. (2009) An Fgf8-Dependent Bistable Cell Migratory Event Establishes CNS Asymmetry. Neuron, 61(1), 27-34. DOI: 10.1016/j.neuron.2008.11.030
- December 1, 2008
- 11:30 AM
- 1,596 views
Tactile-emotion synaesthesia
by Mo in Neurophilosophy
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.
Once believed to be extremely rare, synaesthesia is now thought to be relatively common. The cross-modal connections implicated in the condition are present in all of us, to a greater or lesser extent. Thus, some researchers argue that we all experience synaesthesia-like sensations to some degree, but that these sensations are particularly intense in only some individuals.
Earlier this year, researchers from the California Institute of Technology described a new form of the condition, called hearing-touch synaesthesia, in which moving visual stimuli evoke sounds. Now Vilayanur Ramachandran and David Brang of the Center for Brain and Cognition at the University of California, San Diego report another unusual form of the condition. In the journal Neurocase, they describe the first two known cases of individuals with what they have called tactile-emotion synaesthesia, who experience a specific emotion whenever they touch a particular texture.
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V. S. Ramachandran, & David Brang. (2008) Tactile-emotion synesthesia. Neurocase, 14(5), 390-399. DOI: 10.1080/13554790802363746
- November 25, 2008
- 10:23 AM
- 1,595 views
Blind people are better at finding their way
by Mo in Neurophilosophy
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 location, movement and posture of one's own body through space, and on vestibular information regarding changes in the rotational movements of the head.To compensate for their inability to understand their environment visually, blind persons also store large amounts of non-visual information regarding the spatial organization of their environment, and are more reliant on this information than are sighted individuals. A team of Canadian researchers therefore predicted that blind people would perform better on spatial navigation tasks than sighted individuals, and that they would also show differences in the size of the hippocampus, the region on the inner surface of the temporal lobe which is involved in spatial memory. Remarkably, the study, which is published in the November issue of the journal Brain, confirmed both of these predictions. Read the rest of this post... | Read the comments on this post...... 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
- June 7, 2010
- 06:55 PM
- 1,595 views
Hair pulling is a neuroimmunological condition
by Mo in Neurophilosophy
TRICHOTILLOMANIA (or hair pulling) is a condition characterised by excessive grooming and strong, repeated urges pull out one's own hair. It is classified as an obsessive-compulsive disorder (OCD), and is relatively common, affecting about 2 in 100 people. Sufferers normally feel an increasing sense of tension before pulling out their scalp hair, facial hair, and even pubic hair, eyelashes or eyebrows. This provides gratification, but only briefly.
Hair pulling is usually thought of as being psychological in origin, but an intruiging new study now suggests that it occurs as a result of defects in the immune system. The study, which is published in the journal Neuron, shows that excessive grooming and hair pulling occur in mice because of reduced numbers of microglial cells, which are critical for the brain's immune response. It also suggests - very unexpectedly - that bone marrow transplants may be an effective treatment for trichotillomania in humans.
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Chen, S., Tvrdik, P., Peden, E., Cho, S., Wu, S., Spangrude, G., & Capecchi, M. (2010) Hematopoietic Origin of Pathological Grooming in Hoxb8 Mutant Mice. Cell, 141(5), 775-785. DOI: 10.1016/j.cell.2010.03.055
- February 19, 2009
- 07:30 PM
- 1,585 views
Reading the contents of working memory
by Mo in Neurophilosophy
Working memory refers to the process by which small amounts of information relevant to the task at hand are retained for short periods of time. For example, before cellular phones became so ubiquitous, calling someone usually involved first finding the number and then remembering it for a just few seconds by repeating it to oneself several times. Once the digits had been dialled, they are immediately forgotten.
Very little is known about the neural mechanisms underlying working memory, but very recently some advances have been made. Last month, a group from the University of Texas Medical Center described a novel mechanism by which the response of single cells in the prefrontal cortex to a stimulus can persist for many seconds after the stimulus has been removed. They suggested that this could be how cells encode information for short periods of time.
And now, researchers from Vanderbilt University have made another important finding. In an advance publication in the journal Nature, they report that the parts of the visual cortex which carry out the earliest stages of visual processing play an important part role in retaining simple images in working memory, and demonstrate that the contents of visual working memory can be accurately predicted by decoding neural activity from those parts of the brain.
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Harrison, S.A. . (2009) Decoding reveals the contents of visual working memory in early visual areas. Nature.
Harrison, S.A. . (2009) Decoding reveals the contents of visual working memory in early visual areas. Nature.
- December 22, 2008
- 07:57 AM
- 1,583 views
Rats know their limits with border cells
by Mo in Neurophilosophy
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 which the behavioural psychologist Edward Tolman described his now famous studies of rats in mazes. In that paper, Tolman postulated that "incoming impulses are usually worked over and elaborated...into a tentative, cognitive-like map of the environment...indicating routes and paths and environmental relationships." The paper provided a starting point for modern research into spatial navigation, and after decades of research, much progress has been made in our understanding of how the brain forms cognitive maps.
We now know that the circuitry encoding the cognitive map lies in the hippocampus and surrounding areas, and that these parts of the brain contain at least 3 distinct types of neurons which together encode an organism's location within its environment and the paths it takes to move through it. In the current issue of Science, researchers from the Norwegian University of Science and Technology in Trondheim report that they have discovered a fourth class of neuron involved in spatial navigation.
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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
- February 10, 2009
- 10:15 PM
- 1,577 views
Brain & behaviour of dinosaurs
by Mo in Neurophilosophy
Bones have been big news recently, following the publication of two papers which document remarkable fossil finds. First, a group of palaeontologists led by Phil Gingerich of the University of Michigan described Maiacetus inuus, a primitive whale which lived in the water but gave birth on land, and which marks the transition between modern whales and their terrestrial ancestors. This was quickly followed by the report, from Jason Head's group at the University of Toronto, of Titanoboa cerrejonesis, a prehistoric snake which is estimated to have grown to a length of 13 metres and to weigh more than a tonne.
Such spectacular discoveries always grab the headlines, and rightly so. There are, however, other recent developments in palaeontology, which have been largely overlooked, but are nevertheless equally interesting. The new findings come from Lawrence Witmer's lab at Ohio University's College of Osteopathic Medicine, where the main focus of research is the structure, function and biomechanics of the heads of vertebrates, both living and extinct.
Using sophisticated imaging techniques, Witmer's group scan the skulls of dinosaurs and compare their anatomical structure to those of modern animals. They then use these data to generate detailed three-dimensional digital reconstructions of the soft tissues inside the dinosaur skulls - the muscles, blood vessels, sinuses and brain. Analysis of the reconstructed brains enables them to make inferences about how the prehistoric beasts may have behaved. The Witmer lab is, therefore, effectively bringing dinosaurs back to life.
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Lawrence M. Witmer, & Ryan C. Ridgely. (2008) The Paranasal Air Sinuses of Predatory and Armored Dinosaurs (Archosauria: Theropoda and Ankylosauria) and Their Contribution to Cephalic Structure. The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology, 291(11), 1362-1388. DOI: 10.1002/ar.20794
- October 13, 2008
- 09:45 AM
- 1,565 views
Silver nanorod microscopy
by Mo in Neurophilosophy
Japanese researchers have developed a design concept for a light microscope which could in principle be used for imaging of nanoscale objects. The device would rely on a novel subwavelength imaging technique which allows for the visualization of objects that are smaller than the wavelength of the photons used in the device.
Once thought to be impossible, subwavelength imaging can now be performed because of the development of nanostructured metamaterials with a negative refractive index, which can act as a lens by focusing incident light. Until now though, such materials only worked at one wavelength and could only transfer images over short distances, so their potential for use as lenses was limited.Reporting in a recent issue of Nature Photonics, Satoshi Kawata of the RIKEN Nanophotonics Laboratory and his colleagues propose a lens consisting of stacked silver nanorods, which would be capable not only of colour imaging at a resolution of nanometers using visible light waves, but also of transferring the images over much longer distances. Such a device could be used to directly image viruses or the distribution of protein molecules within cell membranes.
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Satoshi Kawata, Atsushi Ono, & Prabhat Verma. (2008) Subwavelength colour imaging with a metallic nanolens. Nature Photonics, 2(7), 438-442. DOI: 10.1038/nphoton.2008.103
- October 28, 2008
- 01:15 PM
- 1,564 views
An eye-opening view of visual development
by Mo in Neurophilosophy
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 that the proper development of these areas of the brain is dependent upon visual information from the eyes. Their work showed that the visual cortex fails to develop properly if deprived of sensory input during a specific time window. This firmly established the idea of the "critical period", and immediately suggested treatments for young children with eye conditions such as amblyopia ("lazy eye") and strabismus ("crossed eyes").
Now researchers from Duke University Medical Center have observed how early visual experience drives maturation of the visual cortex. Using sophisticated in vivo imaging techniques, they have monitored the changes in the functional properties of visual cortical neurons which occur immediately following eye opening in ferrets. In this way, they show how the first stimuli to enter the eye lead to the emergence of direction selectivity in visually naïve neurons and to the organization of the cells into groups which respond to a preferred direction.
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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
- November 4, 2008
- 08:00 AM
- 1,562 views
You cannot be serious! Perceptual errors by professional tennis referees
by Mo in Neurophilosophy
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 published in Current Biology, in such close calls, professional tennis referees consistently misjudge the location of a ball's bounce because of a perceptual error caused by an inherent property of the visual system. Read the rest of this post... | Read the comments on this post...... 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
- September 11, 2008
- 07:20 PM
- 1,553 views
Neurobiology of a hallucination
by Mo in Neurophilosophy
Hallucinations are often associated with psychiatric conditions such as schizophrenia or with LSD and related drugs. Hearing voices is a characteristic symptom which is reported by about 70% of schizophrenic patients, as well as by some 15% of patients with mood disorders such as depression; and those under the influence of LSD often experience extreme spatial distortions and surreal visions.Most common are auditory and visual hallucinations, but the other senses can also produce mirages. Temporal lobe epilepsy or brain injury can lead to phantosmia, or olfactory hallucinations, during which one detects pleasing or foul smells (e.g. fresh flowers or rotting flesh) that are not actually present. More unusual is a tactile hallucination in which one experiences the sensation of insects crawling under the skin. This can be caused by shingles or cocaine abuse, and is referred to as formication (from the Latin word formica, meaning 'ant').Hallucinations arise spontaneously and are transient in nature, and so the neural activity underlying them is difficult to study. Now though, Dominic Ffytche of the Institute of Psychiatry in London has devised a novel experimental technique with which he has studied the changes that occur in brain activity as an induced visual hallucination is taking place. His findings, which are published in the September issue of the journal Cortex, provide a new theoretical understanding of what happens in the brain during a hallucination. Read the rest of this post... | Read the comments on this post...... Read more »
D FFYTCHE. (2008) The hodology of hallucinations. Cortex, 44(8), 1067-1083. DOI: 10.1016/j.cortex.2008.04.005
- January 13, 2009
- 12:55 PM
- 1,551 views
The evolution of manual dexterity
by Mo in Neurophilosophy
The unique capabilities of the human hand enable us to perform exquisite movements, such as those needed to write or to thread a needle. The emergence of these capabilities was undoubtedly essential in human evolution: a combination of individually movable fingers, opposable thumbs and the ability to rotate the smallest finger and ring finger to meet the thumb in the middle of the palm gives us dexterity that is unparalleled in the animal kingdom.
Last year, geneticists identified a stretch of DNA which has undergone rapid change in humans but not in chimps, our closest relatives, or in other organisms. This short DNA sequence, named HACNS1, regulates the activity of genes involved in limb development. In chimps, it is active only in the upper arm, but in humans, it is active in the part of the hand which is destined to become the thumb, and so it was proposed to have been involved in the evolution of thumb opposability.
Neurobiologists from the University of Pittsburgh have now discovered a neuroanatomical specialization which also seems to have been important in the emergence of manual dexterity. In Proceedings of the National Academy of Sciences, they report that the area of the brain which controls voluntary movement in the higher primates is subdivided into two distinct regions, one of which is evolutionarily more recent and is essential for highly skilled movements.
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J.-A. Rathelot, & P. L. Strick. (2009) Subdivisions of primary motor cortex based on cortico-motoneuronal cells. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.0808362106
- February 5, 2009
- 08:45 PM
- 1,547 views
The genetics of synaesthesia
by Mo in Neurophilosophy
When Sir Francis Galton first described the "peculiar habit of mind" we now call synaesthesia, he noted that it often runs in families. Modern techniques have confirmed that the condition does indeed have a strong genetic component - more than 40% of synaesthetes have a first-degree relative - a parent, sibling or offspring - who also has synaesthesia, and families often contain multiple synaesthetes.
Synaesthesia is known to affect females more than males, and although the female predominance of the condition is now known to have been exaggerated, the condition is presumed to be linked to the X chromosome. A number of genetic studies also support the theory that a single gene is responsible for synaesthesia, and that it is inherited in a dominant manner (in other words, just one copy of the gene, inherited from either parent, is sufficient to cause it).
Researchers from the University of Oxford have now conducted the first genome-wide search for genes linked to the condition. In the American Journal of Human Genetics, they report the identification of a number of genes that are likely to be involved in auditory-visual synaesthesia, in which sounds are perceived as colours. The study reveals also that synaesthesia is not X-linked, and that the genetics of this form of synaesthesia - and probably that of other forms - is far more complex than previously thought.
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Julian E. Asher,1,2,* Janine A. Lamb,3 Denise Brocklebank,1 Jean-Baptiste Cazier, Elena Maestrini,, & Laura Addis, Mallika Sen, Simon Baron-Cohen, and Anthony P. Monaco. (2009) A Whole-Genome Scan and Fine-Mapping Linkage Study of Auditory-Visual Synesthesia Reveals Evidence of Linkage to Chromosomes 2q24, 5q33, 6p12, and 12p12. TheAmericanJournal ofHumanGenetics.
Julian E. Asher,1,2,* Janine A. Lamb,3 Denise Brocklebank,1 Jean-Baptiste Cazier, Elena Maestrini,, & Laura Addis, Mallika Sen, Simon Baron-Cohen, and Anthony P. Monaco. (2009) A Whole-Genome Scan and Fine-Mapping Linkage Study of Auditory-Visual Synesthesia Reveals Evidence of Linkage to Chromosomes 2q24, 5q33, 6p12, and 12p12. TheAmericanJournal ofHumanGenetics.
Julian E. Asher,1,2,* Janine A. Lamb,3 Denise Brocklebank,1 Jean-Baptiste Cazier, Elena Maestrini,, & Laura Addis, Mallika Sen, Simon Baron-Cohen, and Anthony P. Monaco. (2009) A Whole-Genome Scan and Fine-Mapping Linkage Study of Auditory-Visual Synesthesia Reveals Evidence of Linkage to Chromosomes 2q24, 5q33, 6p12, and 12p12. TheAmericanJournal ofHumanGenetics.
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