all neurobiology stories

Neurons created from skin cells of elderly patients with ALS

404132862 — Sun, 27 Jul 2008 12:02:00 -0400

Less than 27 months after announcing that he had institutional permission to attempt the creation of patient and disease-specific stem cell lines, Harvard Stem Cell Institute (HSCI) Principal Faculty member Kevin Eggan today proclaimed the effort a success - though politically imposed restrictions and read more

Newly discovered class of mouse retinal cells detect upward motion

404132862 — Mon, 31 Mar 2008 12:10:06 -0400

Harvard researchers have discovered a previously unknown type of retinal cell that plays an exclusive and unusual role in mice: detecting upward motion. The cells reflect their function in the physical arrangement of their dendrites, branch-like structures on neuronal cells that form a communicative network with other dendrites and neurons in the brain.

The work, led by neuroscientists Joshua R. Sanes and Markus Meister, is described in a letter in the journal Nature.

Transitivity, the orbitofrontal cortex, and neuroeconomics

404132862 — Mon, 10 Dec 2007 10:58:28 -0500

You study the menu at a restaurant and decide to order the steak rather than the salmon. But when the waiter tells you about the lobster special, you decide lobster trumps steak. Without reconsidering the salmon, you place your order — all because of a trait called "transitivity."

Researchers create colorful "Brainbow" images of the nervous system

404132862 — Wed, 31 Oct 2007 14:07:16 -0400

By activating multiple fluorescent proteins in neurons, neuroscientists at Harvard University are imaging the brain and nervous system as never before, rendering their cells in a riotous spray of colors dubbed a "Brainbow."

Scientists identify switch for brain's natural anti-oxidant defense

70652986 — Mon, 26 Mar 2007 05:46:37 -0400

Scientists at Dana-Farber Cancer Institute report they have found how the brain turns on a system designed to protect its nerve cells from toxic "free radicals," a waste product of cell metabolism that has been implicated in some degenerative brain diseases, heart attacks, strokes, cancer, and aging.

Potentially, the researchers say, it may be possible to use drugs to strengthen the anti-oxidant system in the brain as a treatment for presently incurable diseases like Parkinson's, Huntington's, Alzheimer's, and possibly other maladies.

Important signal uncovered in brain development

Thu, 12 Jul 2007 10:51:55 -0400

Nobody has counted them, but the best estimates put the number of human brain cells in the trillions. The best known among them, called neurons, do the heavy thinking and remembering. Each of these cells can connect to 10 or more others, forming a vast network of feelings, thoughts, memories, prejudices, and PINS.

But neurons don't do their jobs alone. They are supported and regulated by an immense system of star cells, called astrocytes, because of their shape. New research has discovered how these stars are born. The discovery also hints at how defective astrocytes may contribute to Alzheimer's disease.

It has been known for years that both neurons and astrocytes come from the same brain stem cells. But how do these cells know whether and when to make one or the other?

Nanowire arrays can detect signals along individual neurons

Thu, 12 Jul 2007 15:58:22 -0400

Opening a whole new interface between nanotechnology and neuroscience, scientists at Harvard University have used slender silicon nanowires to detect, stimulate, and inhibit nerve signals along the axons and dendrites of live mammalian neurons.

Harvard chemist Charles M. Lieber and colleagues report on this marriage of nanowires and neurons this week in the journal Science.

Attention shoppers: Researchers find neurons that encode the value of different goods

70652986 — Mon, 26 Mar 2007 06:26:35 -0400

Researchers at Harvard Medical School report in the April 23, 2006 issue of Nature that they have identified neurons that encode the values that subjects assign to different items. The activity of these neurons might facilitate the process of decision-making that occurs when someone chooses between different goods.

"We have long known that different neurons in various parts of the brain respond to separate attributes, such as quantity, color, and taste. But when we make a choice, for example, between different foods, we combine all these attributes -- we assign a value to each available item," says Camillo Padoa-Schioppa, PhD, HMS research fellow in neurobiology and lead author of the paper. "The neurons we have identified encode the value individuals assign to the available items when they make choices based on subjective preferences, a behavior called 'economic choice.'"

Everyday examples of economic choice include choosing between working and earning more or enjoying more leisure time, or choosing to invest in bonds or in stocks. Such choices have long been studied by economists and psychologists. In particular, research in behavioral economics shows that in numerous circumstances, peoples' choices violate the criteria of economic rationality. This motivates a currently growing interest for the neural bases of economic choice -- an emerging field called "neuroeconomics." In general, it is believed that economic choice involves assigning values to available options. However, the underlying brain mechanisms are not well understood.

In the study, Padoa-Schioppa and John Assad, PhD, HMS associate professor of neurobiology, found a population of neurons located in the orbitofrontal cortex (OFC) that assigns values to different goods on a common value scale. Assigning values on a common scale allows comparing goods, like apples and oranges, that otherwise lack a natural basis for comparison.

Protein underlies brain's response to activity

70652986 — Mon, 26 Mar 2007 06:25:00 -0400

Experience helps shape the brain, but how that happens - how synapses are remodeled in response to activity - is one of neurobiology's biggest mysteries. Though axons and dendrites can be easily spotted waxing and waning under the microscope, the molecular middlemen working inside the cell to shape the neuron's sinewy processes have been much more elusive.

Two independent teams of Harvard Medical School (HMS) researchers report that they have found a protein that either pares down or promotes a neuron's synapses, depending on whether or not the neuron is being activated. Rather than work at the far reaches of the cell, in the axon or dendrite, the protein myocyte enhancer factor 2 (MEF2) resides in the nucleus, where it turns on and off genes that control dendritic remodeling. In fact, the researchers have identified some of MEF2's targets. In addition, one of the teams has identified how MEF2 switches from one program to the other, that is, from dendrite- promoting to dendrite-pruning. The discoveries are reported in back-to-back papers in the Feb. 17, 2006 Science.

The uncovering of the MEF2 pathway and its genetic switch helps fill in a theoretical blank in neurobiology, but what excites the researchers are the potential implications for the clinic. "Changes in the morphology of synapses could turn out to be very important in a whole host of diseases including neurodegenerative as well as psychiatric disorders," said Azad Bonni, HMS associate professor of pathology, who, with research fellow Aryaman Shalizi, HST medical student Brice Gaudilliére, and colleagues, authored one of the papers. Graduate student Steven Flavell and Michael Greenberg, HMS professor of neurology at Children's Hospital Boston, who led the other team, believe that the MEF2 pathway could play a role in autism and other neurodevelopmental diseases.

Brain protein may play role in innate and learned fear

70652986 — Mon, 26 Mar 2007 05:42:30 -0400

In a paper published in the November 2005 issue of Cell, researchers reported that the protein stathmin is essential for the fear response - both the expression of innate fear and the formation of memory for learned fear.

Previous studies had shown that the amygdala, a brain structure important for emotional responses, is the place where fear memory is formed.

"This is the first time it has been shown that the protein called stathmin - the product of the stathmin gene - is linked to fear conditioning pathways," said Vadim Bolshakov, PhD, director of the Cellular Neurobiology Laboratory at McLean Hospital. The study is the collaborative effort of Bolshakov's lab at McLean and those of Eric Kandel at Columbia University and Gleb Shumyatsky of Rutgers. Kandel is the winner of the 2000 Nobel Prize in physiology or medicine.

The researchers for some time have been studying how changes in the brain may affect learning and memory. In earlier animal studies, Bolshakov and Kandel were able to measure changes in the brain and correlate them with changes in behavior associated with learning.

This study, using mice, demonstrated that those that were genetically modified so they would not produce stathmin showed deficits in neural transmission and exhibited decreased memory in fear conditioning and the failure to recognize danger in innately aversive environments. Learned fear develops after conditioning and lasts for life.

"The evidence that stathmin is important in the regulation of fear suggests that stathmin knockout mice can be used as a model of anxiety states or mental disorders with innate and learned fear components," the paper said.

In the future, these animal models may be used to develop new anti-anxiety drugs, Bolshakov added.

An existing diuretic may suppress seizures in newborns

70652986 — Mon, 26 Mar 2007 05:41:50 -0400

A diuretic drug called bumetanide may serendipitously help treat seizures in newborns, which are difficult to control with existing anticonvulsants, according to a study in the November 2005 Nature Medicine. The study findings could lead to clinical trials of bumetanide in newborns, whose immature, rapidly- developing brains are especially vulnerable to seizures - particularly preterm newborns, in whom seizure incidence can range to over 2 percent. Newborns' seizures can cause long- term neurologic impairments and a tendency toward seizures later in life.

Conventional anticonvulsants - phenobarbital and benzodiazepines - are ineffective in newborns because their brains are biochemically different from adult brains, says neurologist Frances Jensen, MD, of Children's Hospital Boston, a senior investigator on the study. Jensen's team, led by postdoctoral fellow Delia Talos, PhD, collaborated with Kevin Staley and colleagues at the University of Colorado Health Sciences Center to find a treatment for seizures that would work in newborns.

Seeing seeing in action

50443248 — Wed, 25 Jul 2007 14:07:29 -0400

Harvard Medical School researchers are seeing what seeing does to the brains of animals and making images that show for the first time single brain cells working together.

The work, by Professor of Neurobiology Clay Reid and colleagues from Harvard Medical School, combines existing imaging techniques to create high-resolution movies of the working brain.

Previous techniques have been able to measure the firing of single brain cells, but have done so blindly. Reid said the old technology is like walking through a cocktail party with one's eyes closed and hearing conversations but never being exactly sure who's speaking. The new techniques take those blinders off, allowing researchers to even make time-lapse images of groups of nerve cells firing in response to visual stimulation.

First view of many neurons processing information in living brain

70652986 — Mon, 26 Mar 2007 05:36:18 -0400

A Harvard Medical School (HMS) research team used a new technique to obtain the first close-up look at the neural circuits that produce vision in cats and rats. "Put simply, this technique allows us to see the brain seeing," said R. Clay Reid, HMS professor of neurobiology, a member of the HMS Systems Neuroscience initiative, and principal investigator on the project. "It's an entirely new way of looking at brain function." The method, the first to track the responses of all the neurons in a visual circuit simultaneously, promises to rapidly advance our understanding of how the brain is wired for complex image processing. Lessons learned by studying the visual system may eventually apply to other brain functions like movement, thinking, and learning, as well as neurodegenerative diseases. The results were reported in the Jan. 19, 2005 issue of the journal Nature.

Newly identified gene linked to brain development

70652986 — Mon, 26 Mar 2007 07:10:26 -0400

Bilateral frontoparietal polymicrogyria (BFPP) is a recessive genetic disorder resulting in severely abnormal architecture of the brain's frontal lobes, as well as milder involvement of parietal and posterior parts of the cerebral cortex, which is "the part of the brain that distinguishes humans from other species," says the study's senior author, Christopher A. Walsh, M.D., Ph.D., a Howard Hughes Medical Institute investigator at BIDMC's Neurogenetics Division and Bullard Professor of Neurology at Harvard Medical School.

In this new study, lead author Xianhua Piao M.D., Ph.D., and colleagues identified the BFPP gene as GPR56, which plays an especially important role in the frontal portions of the cortex.

Walsh's laboratory identifies genes that disrupt the normal cerebral cortex development, thereby helping to define the clinical syndromes of certain human developmental disorders. These new findings, he says, suggest that GPR56 may have been a key target in the evolution of the cerebral cortex.

"Being able to access the complete sequence of the human genome has allowed us to identify increasing numbers of genes that are required for cortical development," he adds. "Although these genes cause mental retardation, by studying the biological function of their gene products we also gain insight into the normal development and function of the human brain."

The brains behind writer's block

70652986 — Mon, 26 Mar 2007 05:34:58 -0400

"It's likely that writing and other creative work involve a push-pull interaction between the frontal and temporal lobes," Harvard Medical School neurology instructor Alice Flaherty speculates. If the temporal lobe activity holds sway, an aspiring scribe may turn out 600 logorrheic pages. If the temporal lobes are restrained by frontal lobe changes, the result might be pinched and timid. Most academics regard the study of creativity as what Flaherty calls "intellectually unhygienic." So Flaherty, who has herself experienced a compulsion to write, is doing it herself. She and Shelley Carson, a psychologist at Harvard, have tried using light to break writing blocks and prod creativity. As autumn wears on, many people experience a dip in productivity and originality, not dissimilar to the gloomy seasonal affective disorder (SAD) that depresses some people when the days get darker and colder. SAD can be relieved by sitting in front of light boxes that provide an indoor equivalent of a sunny day. Flaherty and Carson have begun trying to up the creativity of college students with the same treatment. Flaherty is the author of "The Midnight Disease" (Houghton Mifflin, 2004), in which she writes about the mental aspects of writing.