neuroscience
neurophilosophy | August 1, 2007 This essay I wrote was shortlisted in the Association of British Science Writers competition in 2002. It was the first thing I posted on the old blog.
It was written as an introduction to what were generally believed to be the fundamentals of brain function, starting from the molecular level and working all the way up.
But our understanding of the brain has advanced dramatically since then, and there is now evidence to suggest that some of these assumptions are now wrong.
For example, it was, I think, taken for granted that all neurons fire action potentials, but it now appears that…
neurophilosophy | July 31, 2007 Females have a natural preference for mating with dominant males, because this confers a genetic advantage upon the offspring produced. When selecting a mate, animals rely on chemical cues called pheromones, which relay information about the social status and genetic health of a potential mate.
Reproductive success therefore depends upon the encoding and recall of olfactory memories; the neural circuitry in which these memories are formed consists of the olfactory bulb and the dentate gyrus of the hippocampus. But although both these sites are principle regions for neurogenesis (formation…
neurophilosophy | July 31, 2007 Encephalon #28 is now online at the Bohemian Scientist's blog.
The next edition will be hosted at Memoirs of a Postgrad on August 13th. If you'd like to contribute, send permalinks to your neuroscience or psychology blog posts to encephalonb.hoat{at}gmail{dot{com}, or use this submission form.
neurophilosophy | July 29, 2007Black peoples' brains are, of course, no more or less peculiar than those of any other people. The human brain is an extraordinarily complex organ, and there are just as many differences between the brains of people from the same ethnic group as there between the brains of people from different groups.
Some racial peculiarities of the Negro brain is the title of a long and technical paper by the anthropologist Robert Bennett Bean, published in the American Journal of Anatomy in 1906. It is one of a series of scientific papers written by Bean in the early 20th Century, in which he tried to…
neurophilosophy | July 28, 2007The single most famous case study in the history of neuropsychology is that of an anonymous memory-impaired man usually referred to only by the initials H.M. This patient has one of the most severe cases of amnesia ever observed; he has been followed for over 40 years by more than 100 researchers, and is the subject of dozens of research papers and book chapters. The early studies of H.M. provide a basis for modern neuropsychology, and the findings of those who have studied him are today a cornerstone in memory research.
H.M. (sometimes referred to as Henry M.) was born in Hartford,…
neurophilosophy | July 28, 2007
My recent post on prefrontal lobotomy has been the most popular thing on this blog so far, and the comments on it are worth reading.
While searching for more information about lobotomies and the neuroleptic drugs that replaced them, I came across this fantastic webpage at NobelPrize.org, which contains more information about Egas Moniz, the Portugese surgeon who first performed the procedure.
That's where I found this diagram of the instrument designed by Moniz for the prefrontal leucotomies he performed with his colleague. From the diagram, one can see how the instrument (called a…
neurophilosophy | July 27, 2007 Shelley has written a nice summary of the neuroscience of attention deficit hyperactivity disorder (ADHD).
As its name suggests, ADHD is characterized by inattention and hyperactivity. This is often accompanied by forgetfulness and an inability to control impulses.
ADHD is a developmental disorder that is believed to be neurological in nature. It presents at an early age and persists into adulthood in about 60% of cases.
The condition has proven to be highly controversial in recent years. Some believe that we are too quick to diagnose it, and that children are being over-medicated.…
omnibrain | July 27, 2007Stop smoking pot immediately! You WILL go CRAZY!!! Panic!
The study by Zammit and colleagues, published in the medical journal the Lancet, reanalyzed data from seven long-term studies on psychotic illnesses and marijuana involving 61,000 participants.
The researchers filtered out about 60 factors, such as preexisting mental illness and the use of other illicit drugs, and considered IQ and social class, to try to isolate the effect of marijuana, Zammit said.
Most of the studies that were analyzed indicated a range of increased risk for frequent users from 50% to 200%, with the average being…
clock | July 26, 2007Bjoern Brembs is at the ICN meeting and is blogging about the talks he saw. If I went, I would have probably attended a completely different set of talks, e.g., on birdsong, memory in food-caching birds, aggression in crustaceans, strange sensory systems, spatial orientation and animal cognition, but I am certainly glad that Bjoern has highlighted the best of what he saw there:
Robert de Ruyter van Steveninck: Velocity estimation and natural visual input signals
Martin Egelhaaf: Active vision: a strategy of complexity reduction in behavioral control
Roy Ritzmann: Movement through complex…
clock | July 26, 2007It is certainly possible. Compared to some people I know, I am definitely not. I have read each of the books once (more than halfway through the 7th - so do not give me spoilers yet!) and I have seen each of the movies once. I enjoy them, but do nothing on top of it: no speculations, no obsessions, no additional activity.
clock | July 26, 2007Mo is really spoiling us with exciting, well-researched posts from the history of science and medicine (remember the trepination post from a month ago?). And here he does it again: The rise & fall of the prefrontal lobotomy, the most gripping post on science blogs this week. And a Wicked Stepmother is one of the main characters!
neurontic | July 24, 2007"We saw that the group with high level of leisure activities presented 38% less risk of developing Alzheimer's symptoms."
Dr. Yaakov Stern, Professor of Clinical Neuropsychology, at the College of Physicians and Surgeons of Columbia University, New York.
Read this interview with Dr. Stern on Sharp Brains, to learn more about building up your "cognitive reserves."
j7uy5 | July 22, 2007As
reported in the journal, The Lancet, a man has
been found who had a
small brain, but a normal life. The article is subscription
only so I am not even going to link to it. But it is still
noteworthy.
There is a fair summary in the online version of
href="http://www.spiegel.de/international/zeitgeist/0,1518,495607,00.html">Der
Spiegel, and it is even in English. It
describes the case of a 44-year-old man employed in a tax office.
He was married, father of two, holding down a job, seemingly
fine.
In 2003 he noticed some weakness in his left leg.
He ultimately was seen by Dr…
neurophilosophy | July 21, 2007We live in a time in which we are overwhelmed by information obtained from multiple sources, such as the internet, television, and radio. We are usually unable to give our undivided attention to any one source of information, but instead give 'continuous partial attention' to all of them by constantly flitting between them. The limitations of cognitive processes, particularly attention and working memory, place a ceiling on the capacity of the brain to process and store information. It is these processes that some researchers are aiming to enhance with augmented cognition, an emerging field…
j7uy5 | July 21, 2007The
href="http://www.sanofi-aventis.us/live/us/en/index.jsp">Sanofi-Aventis
obesity pill,
rel="tag">rimonabant, will be labeled with
stronger warnings as a result of
href="http://www.irishhealth.com/?level=4&id=11864">a review
by The European
Medicines Agency (EMEA).
According to the
href="http://www.emea.europa.eu/humandocs/PDFs/EPAR/acomplia/32982607en.pdf">EMEA
press release on Acomplia (31 KB PDF file):
The
European Medicines Agency (EMEA) today recommended contraindicating
Acomplia (rimonabant) from sanofi-aventis, in patients with ongoing
major…
j7uy5 | July 19, 2007There
was an outbreak of botulism in the past several days in the
United States. The problem was traced to contaminated canned
chili sauce intended for use on hotdogs. Product from
Castleberry Food Company based in Augusta, Georgia is suspected.
But what is botulism, exactly, and how/why is it so lethal?
There
are actually three different ways to get botulism. The
most common occurs when a person eats improperly canned food, usually
food canned at home. It is also possible for human infants to
get botulism when they are fed something that contains live spores.
Most often, the…
neurophilosophy | July 19, 2007 Nerve cells are excitable. At rest, they are said to be polarized; the cell membrane separates the negatively and positively charged ions, so that the inside of the membrane is negatively charged with respect to the outside. In response to a stimulus, nerve cells produce action potentials, which are generated by the rapid movements of ions (negatively or positively charged atoms) across the nerve cell membrane. These ion fluxes lead to depolarization, or a transient reversal of the membrane voltage - the inside of the membrane becomes positively charged, and vice versa.
The action…
neurophilosophy | July 18, 2007
How the brain interprets complex visual scenes is an enduring mystery for researchers. This process occurs extremely rapidly - the "meaning" of a scene is interpreted within 1/20th of a second, and, even though the information processed by the brain may be incomplete, the interpretation is usually correct.
Occasionally, however, visual stimuli are open to interpretation. This is the case with ambiguous figures - images which can be interpreted in more than one way. When an ambiguous image is viewed, a single image impinges upon the retina, but higher order processing in the visual cortex…
j7uy5 | July 18, 2007
There is new information
indicating that an
rel="tag">oxytocin
nasal spray could be used to
treat shyness. Oxytocin is a peptide hormone best known for
its role in childbirth and breastfeeding. These are known as
peripheral actions, meaning they take place outside of the central
nervous system (CNS).
However,
it also is
known as a neurotransmitter, having effects within the CNS.
It
has been touted as a chemical that can increase trust and reduce fear.
It also has been claimed to have a role in the difference in
how
href="http://www.suntimes.com/lifestyles/471090,CST-FTR-…
neurophilosophy | July 17, 2007Soon after the discovery of the neuron as the basic functional unit of the nervous system, a model of how nerve cells function emerged. According to this model - the neuron doctrine - the cell body integrates nervous impulses received by the dendrites, and generates an output, in the form of a train of impulses with a specific pattern, which is propagated along the axon. When these impulses reach the nerve terminal, they elicit the release of neurotransmitters, which diffuse across the synapse and bind to receptors embedded in the dendrite membrane of the adjacent cell.
This model soon…