neuroscience
j7uy5 | November 2, 2007
rel="tag">Anhedonia
is one of the most important symptoms of depression. I wrote
href="http://scienceblogs.com/corpuscallosum/2007/03/basic_concepts_anhedonia.php">a
post about it a while back, so I won't go into the definition
in this post, other than to summarize by saying that it is the
inability to experience pleasure in response to activities or events
that otherwise would be pleasurable.
It is difficult to do studies on the brain mechanisms involved in the
genesis of individual symptoms. Progress has been made, but
it has been slow.
When I was in residency, toward the end…
neurophilosophy | November 2, 2007
On November 4th, 1906, during a lecture at the 37th Conference of South-West German Psychiatrists in Tubingen, the German neuropathologist and psychiatrist Alois Alzheimer (1864-1915, right) described "eine eigenartige Erkrankung der Hirnrinde" (a peculiar disease of the cerebral cortex). In the lecture, he dicussed "the case of a patient who was kept under close observation during institutionalisation at the Frankfurt Hospital and whose central nervous system had been given to me by director Sioli for further examination". This was the first documented case of the form of dementia that…
purepedantry | November 2, 2007
Every so often, I encounter a technical advance that is simply so crazy-cool that I have to talk about it. Dombeck et al. publishing in Neuron offer such an advance.
They found a way to image the activity of whole fields of neurons using two-photon fluorescent microscopy -- a technique that I will define in a second. They can do this with in mice that are actually behaving by mounting the mouse in an apparatus that lets the mouse run on a track ball floating on air -- just like air hockey. (I want to meet the person who came up with that. There had to be high-fives all-around.)…
neurophilosophy | November 1, 2007
The ability to attend to multiple moving objects simultaneously is fundamental to many of the tasks we perform regularly, such as driving, or taking part in team sports.
Numerous studies in which participants are asked to track dots moving around on a screen have led researchers to the conclusion that 4 is the maximum number of objects that can be tracked. It is therefore widely believed that the "magical number" 4 is the fixed upper limit of visual attention.
This has, therefore, led to the assumption that the visual system has a "fixed architecture" which places a limit on the number of…
neurophilosophy | October 31, 2007
Researchers from Harvard University have developed a remarkable genetic technique that enabled them to visualize complete neuronal circuits in unprecedented detail, by using multiple distinct colours to label individual neurons.
The technique, called Brainbow, works in much the same way as a television uses the three primary colours to generate all the colour hues. With multiple combinations of up to four differently coloured fluorescent proteins, a palette of approximately 100 labels has been produced.
To develop Brainbow, the researchers used the Cre/loxP site-specific recombination…
neurophilosophy | October 31, 2007Fear, that most primitive of emotions, is good, at least when it is kept under control. It is essential for survival, allowing an organism to detect a potential threat to its life. Too much fear, however, can lead to pathological conditions such as anxiety, phobia, paranoia, or post-traumatic stress disorder.
The neural circuitry which processes information about fear is well mapped, but otherwise, little else is known about the biological basis of this emotion. In recent years, however, neuroscientists elucidated some of the cellular and molecular mechnisms underlying fear. A greater…
omnibrain | October 31, 2007
Ahh Halloween - when neuroscientists find all sorts of fake brains for sale and recipes to create them. This is our yearly reposting of the greatest brain recipe of all time.
This recipe was inspired by the one Alton Brown did a few years back. I liked the idea but wasn't thrilled with the recipe, so I came up with my own. By the way, I would suggest getting this mold - it looks a lot more lifelike.
Panna Cotta (brain style) with Pomegranite Sauce
Get the recipe below the fold!
1 cup milk
5 teaspoons unflavored gelatin
4 cups heavy cream
1 cup + 1 Tb sugar, divided
pinch salt
2 Tablespoons…
neurophilosophy | October 30, 2007
An article about Oliver Sacks, from the current issue of Seed magazine, has just just been made available online.
Author Jonah Lehrer, who met with Sacks to research the article, provides interesting biographical details about the neurologist, including how he started out as a science writer.
In the late 1960s, Sacks carried out a clinical study in which a new drug called L-dopa was used to treat patients with encephalitis-induced Parkinsonian symptoms. The study drew heavy criticism, because the treatment had severe side effects, and the symptoms eventually returned in all of the patients.…
j7uy5 | October 30, 2007Medscape
has an article about a study that shows a relationship between the
amount of eduction a person has, and how rapidly memory loss occurs
when they get senile dementia of the Alzheimer type (SDAT).
The more education a person has, the faster the memory loss
occurs. (
href="http://www.medscape.com/viewarticle/564996">Higher
Education Delays Dementia Onset but Is Linked to More Rapid Progression,
free registration required)
At first this seems counterintuitive. But think about it.
Speaking
of memory, I remember when I was in college, there was a newspaper
article about a kid who…
neurophilosophy | October 29, 2007
Bertalan has found the Virtual Labs Series, a fantastic educational resource produced for science teachers and students by researchers at the Howard Hughes Medical Institute.
The series includes the Transgenic Fly Virtual Lab, the Bacterial Identification Lab, the Cardiology Lab, the Immunology Lab and - my favourite - the virtual Neurophysiology Lab.
Each of the virtual labs has an interactive set of the appropriate apparatus, which comes complete with background information about the experimental setup to be used and the underlying biological concepts.
At the virtual neurophysiology…
neurophilosophy | October 27, 2007The Guardian reports that the Ministry of Defence has just started a major study into traumatic brain injury (TBI) in British troops returning from Iraq and Afghanistan.
In an accompanying article, the behavioural, cognitive, emotional and physical symptoms of this "silent injury" are described by the father of an American soldier who sustained TBI during a 24-month tour of duty in Iraq.
The official figures on TBI in American troops are based only on cases involving a penetrative head wound, and evidence published earlier this year in the Journal of Neurosurgery suggests that the high…
neurophilosophy | October 26, 2007The new issue of Current Biology has a freely available primer on the amygdala by Joseph LeDoux of the Center for Neural Science at New York University.
The amgdala is a small, almond shaped structure found on the medial surface of the temporal lobe, just anterior to the hippocampus. Functionally, it can be thought of as junction between the neural circuits involved in memory and emotion. These two phenomena are intimately linked, and the amygdala is now known to be crucial for that link.
LeDoux is the ideal person to write a primer on this brain structure, as he is one of the world's…
neurophilosophy | October 26, 2007
Some 365 million years ago, during the early Devonian period, the Sarcopterygian (or lobe-finned) fish emerged from the sea and gave rise to the first terrestrial tetrapods.
During the course of their evolution, the tetrapods became adapted to life on land. One big challenge faced by the earliest tetrapods was how to interpret the rich tapestry of visual information to which their aquatic ancestors were all but oblivious.
One would think that, having evolved from fish, the visual systems of the early tetrapods would have been poorly adapted to life on land. But new research, just…
j7uy5 | October 26, 2007The Clean Air Act was passed in 1970, and amended in 1977
and 1990.
It has been mildly controversial, but most people supported
it then and support it now.
A retrospective
economic analysis done in the early 1990's indicated that the
cost of implementation from 1970 to 1990 had been about $523 billion in
1990 dollars. What did we get for that money? The
same study indicated that the economic benefit had been somewhere
between $5.6 to $49.4 trillion,
with a mean (among various scenarios) of $22.2 trillion.
Allowing for various uncertainties, it was estimated that the
benefit/cost ratio…
neurophilosophy | October 25, 2007
This film from the Technology, Entertainment and Design (TED) website features a 24-minute talk called A Journey to the Center of the Mind, by neuroscientist and neurologist V.S. Ramachandran, who heads the Center for Brain and Cognition at the University of California in San Diego.
In his talk, "Rama" discusses synaesthesia, phantom limb syndrome (including the case of a woman who experienced phantom menstrual cramps after having her uterus surgically removed), and Capgras Syndrome, a bizarre condition in which patients with damage to the fusiform gyrus believe…
neurophilosophy | October 25, 2007David Chalmers, a professor of philosophy at the Australian National University and director of the Center for Consciousness, has just announced the launch of MindPapers, an online database of papers about the philosophy of mind.
The database is very comprehensive indeed - it includes about 18,000 published and online papers, subdivided into sections such as the philosophy of neuroscience, perception, synaesthesia, language and thought and vegetative states, coma and the minimally conscious state (which are disorders of consciousness).
cortex | October 24, 2007An intriguing new hypothesis that seeks to explain all of the diverse psychological symptoms associated with autism. Here's the abstract:
While significant advances have been made in identifying the neuronal structures and cells affected, a unifying theory that could explain the manifold autistic symptoms has still not emerged. Based on recent synaptic, cellular, molecular, microcircuit, and behavioral results obtained with the valproic acid (VPA) rat model of autism, we propose here a unifying hypothesis where the core pathology of the autistic brain is hyper-reactivity and hyper-plasticity…
neurophilosophy | October 24, 2007
(Image credit: Alex Klochkov)
Here is a rather macabre set of photographs by Alex Klochkov, apparently taken in an abandoned Russian brain research laboratory.
neurophilosophy | October 23, 2007According to Efstratios Manousakis, a professor of condensed matter physics at Florida State University in Tallahassee, the key to consciousness could be lie in the quantum effects that occur in the brain when one is viewing ambiguous figures like the spinning silhouette (or Rubin's vase or the Necker Cube).
These optical illusions are ambiguous because at any one instant they can be perceived either in one way, or in the other, but not in both. The image is said to "flip" when our perception changes from one interpretation of the image to the other. In the case of the spinning silhouette…
neurophilosophy | October 23, 2007The New York Times science section has a special issue devoted to sleep.
The feature contains about 10 articles about recent findings in sleep research, including one by Carl Zimmer on how studies carried out on birds are informing us about the functions of sleep.
The title of the post is from a quote that is often attributed to Edgar Allan Poe: "Sleep, those little slices of death; Oh how I loathe them."