The Neuroscience of Idle Minds

http://www.nature.com/news/neuroscience-idle-minds-1.11440

This article explains how the brain is active when at rest and considers the implications of this. 

There is a myriad of activity occurring in our brains, even as we sleep. It is important to distinguish, however, between brain activity and conscious thoughts. Just because a person is having (or thinks he is having) no conscious thoughts, or even if he is unconscious, there is still masses of activity flowing through his brain. 

I think they will find that while our brains rest - whilst we are lounging idly on the sofa, for example - our brains are consolidating memories formed throughout the day. So, it's probably best to take a break after studying and do nothing, rather than watch TV, or socialise, even. 

I also reckon memories aren't, as previously thought, merely set pathways through which a current flows which make up a conscious recall of a stimulus. I think they can change, and perhaps 'exist' in many places at once, constantly being reformed and manipulated through processes such as neuroplasticity. 

It is also suggested that the brain can reuse past experiences to 'prime' connections which may be useful in the current situation. For example, if we are crossing a busy road, not only would we be consciously aware that we are in danger, but the motor sections of our brain would be primed so that we are more prepared to dodge that oncoming bus. 

I particularly like the analogy: 

“If your car is ready to go, you can leave faster than if you have to turn on the engine.”

The brain is surprising similar to any other machine; yet vastly different and infinitely complex.  

Did Your Brain Make You Do It?

There seems to be a phenomenon prevalent across much of Western society. People don't like to accept responsibility for their own actions when they've done something wrong. They'd much rather say it that their actions were due to "a complex sequence of chemical reactions within my brain", over which they, supposedly, had no control, and therefore it's not their fault - they're innocent. Of course, the premise is true - we, and all our actions, are the result of various biochemical reactions throughout our bodies. However, that doesn't mean that they're not in our control. That's loosely analogous to saying, "Oops, my car lost control and killed someone - but it was the road conditions; there was nothing I could do." (Yes, it makes no sense)

But what about if our driver had lost control, but instead of killing someone, had collided with another car and changed it's course, when that other car would otherwise have hit a pedestrian? It's unlikely then that the driver would attribute the events to road conditions out of their control. No, they would claim it was their own fast thinking, bravery and heroism that saved the pedestrian's life.

It's nothing new, this phenomenon. It's part of a standard sixth-form psychology course, dubbed 'situational factors' vs 'dispositional factors', or 'self-serving bias'.

However, this likely only applies to Western societies - more collectivist societies would likely attribute their errors to themselves (that is, if they knew that their every move is the result of the workings of the brain). That is because they have a more utilitarian approach; they care more about the good of the society than the consequences they themselves may face. 

My point is, it's a cultural phenomenon, not a neuroscientific one. It's about whether people see themselves as a living being forming a part of a group of living beings for which they are partly responsible; or as an individual biological organism reacting with other individual biological organisms. Of course, both views are true - thus, neither are valid as an argument. You can never say "my brain made me do it" and you can never say "it was my fault, not my brain's", since both are equally true. It just depends how you look at it. 

Pointless argument, really. 

(N.B. I'm referring to adults here, not adolescents whose brains may or may not have fully developed self-control abilities. But this poses a further question - who decides what "fully developed self-control abilities" are? All brains are different, ergo, people have varying "self-control abilities". Do people turn 18 and suddenly reach a baseline level of self-control?)

Common parasite that lives in the bodies of 10 - 20% of Americans linked to a sevenfold higher risk of attempted suicide

http://www.medicalnewstoday.com/articles/249230.php

 

Testing positive for a common parasite that lives in the bodies of 10 - 20% of Americans is linked to a sevenfold higher risk of attempted suicide, according to new research.

I found this article pretty interesting since it furthers the hypothesis that depression is a biological disorder with real, physiological, biochemical roots. It proposes that inflammation and other effects within the brain caused by a common parasite which up to 1 in 5 people host can lead to a drastically increased "risk of attempted suicide".

However, I would like to know exactly what this means. The supposed "risk" is measured on a "suicide assessment scale" - but surely the risk of suicide is something which is subjective to each person. Also, the perception of the "risk of suicide" in the subject could vary greatly depending on the background and/or mental health of the person evaluating the risk.

One must also bear in mind that the sample only included 84 people - 54 attempted suicide patients and 30 controls. All were adults. I'd expect to see a sample of at least a few hundred for a study like this.

Nonetheless, this paves the road for a whole new area of study - the physiological effects of parasites on the brain and the psychological impact of these effects.

Doubts regarding research suggesting that “A Very Sugary Diet Makes You Stupid”

Read the article(s):
http://www.medicalnewstoday.com/articles/245531.php
http://newsroom.ucla.edu/portal/ucla/this-is-your-brain-on-sugar-ucla-233992.aspx

I have some doubts about the conclusions reached in this research.

“As a control, the animals were fed on standard rat feed for five days before the fructose diet started. They were also trained on a maze twice per day and tested to see how well they performed. They also placed visual markers in the maze to help the rats remember their way around.”

 Gomez-Pinilla recounts his experience of testing the rats after six weeks on the sugary diet:

    “The second group of rats navigated the maze much faster than the rats that did not receive omega-3 fatty acids … The DHA-deprived animals were slower, and their brains showed a decline in synaptic activity. Their brain cells had trouble signaling each other, disrupting the rats’ ability to think clearly and recall the route they’d learned six weeks earlier.”

Maybe, rather than omega-3 fatty acids negating a negative effect of fructose on synaptic activity, omega-3 combined with fructose may have enhanced activity and protected from damage to the synapses, leading to the rats’ increased performance in the maze tests.

“Our findings suggest that consuming DHA regularly protects the brain against fructose’s harmful effects …”

The researchers appear to have arrived at the conclusion that fructose (in abundance?) may have negative effects on cognitive activity and memory. I don’t believe that the results of this experiment necessarily point to this conclusion.

Both groups of rats were fed fructose, with the second group also being fed omega-3 fatty acids in the form of flaxseed oil and docosahexaenoic acid (DHA)
There should have been a further control group which was not fed fructose at all, to compare the other two groups against. This would determine whether fructose had any effect on the rat’s brain and performance in the maze tests, prior to investigating any effect that omega-3 fatty acids may have in “negating” this effect. Instead, the researchers gave fructose solutions to both groups of rats.

The UCLA article also suggests that the first group of rats, who did not receive omega-3 fatty acids, may have developed a resistance to insulin:  

"The DHA-deprived rats also developed signs of resistance to insulin, a hormone that controls blood sugar and regulates synaptic function in the brain. A closer look at the rats’ brain tissue suggested that insulin had lost much of its power to influence the brain cells."

"He suspects that fructose is the culprit behind the DHA-deficient rats’ brain dysfunction. Eating too much fructose could block insulin’s ability to regulate how cells use and store sugar for the energy required for processing thoughts and emotions."

I believe that this is the more appropriate route for the experiment to proceed. However, it is unclear whether it is fructose itself that is responsible for the DHA-deprived rat’s lower performance, or an interaction between insulin and fructose in the absence of omega-3 fatty acids.

More research should be done to determine an effect of fructose on the rats’ brain and performance, compared against a baseline, control group of rats who are not fed fructose solutions.

Nonetheless, it is known that omega-3 fatty acids protect the brain and enhance cognitive function and memory. However, it is not correct to conclude from this article that fructose has any negative effect on the brain.

Neurotransmitters Identified That Lead To Forgetting

Read the article: http://www.medicalnewstoday.com/releases/245228.php

Just some thoughts;

“This also might be a strategy for developing drugs to promote cognition and memory – what about drugs that inhibit forgetting as cognitive enhancers?"

But surely forgetting is essential for normal day-to-day functioning? Remembering too much trivial information about your day would undoubtedly be undesirable, and maybe this “information overload” leads to some of the undesirable symptoms of savantism.

Also, considering dopamine’s known roles in the reward-pathways, perhaps savants get a “kick” out of learning excessive amounts of information, due to a faulty dopamine receptor/mechanism (DAMB), or an overactive dDA1?

Perhaps this research could have implications for dementia, too.

The Future of Neuroscience: Changing The Brain to Enhance…

I thought I’d write a post concerning my disapproval of this article. It seems to be a running theme that I disagree with articles from PsychCentral.

“Changing The Brain to Enhance Well-Being, Happiness” 

http://psychcentral.com/news/2012/04/19/changing-our-brain-to-enhance-well-being-happiness/37566.html

The article basically states what has been long known – that physical exercise, certain forms of psychological counseling (for some people) and meditation can all increase our well-being. That’s all well and good.

Then comes the part I don’t like: 

“The study reflects a major transition in the focus of neuroscience from disease to well-being.”

I think neuroscience is a great, fascinating subject which has a promising outlook for the near future, with beneficial applications such as the treatment of disease and the study of the human brain/mind. However, when we start using neuroscience to improve our “well-being”, we introduce a plethora of potential dangers and moral issues.

The goal is “to use what we know about the brain to fine-tune interventions that will improve well-being, kindness, altruism. Perhaps we can develop more targeted, focused interventions that take advantage of the mechanisms of neuroplasticity to induce specific changes in specific brain circuits.”

Not only is this sort of research reducing the time spent researching treatment for diseases such as Alzheimer’s and Parkinson’s (which is much more important at the current time) it also represents the start of a revolution – the designer-brain revolution. Digressing from the article (although relevant), it won’t be long until we can purchase “add-ons” to enhance our well-being, intellect, kindness, altruism etc. “Add-ons” could also be developed to add “additional-features” to the brain, much like add-ons for Firefox.

People will be purchasing these add-ons to enhance their ability; to gain the upper-hand and improve their lives. However, it can be dangerous to modify nature, especially when it comes to the brain. Since the brain is such a complex organ and is fundamental to our conscious existence, tinkering with it could be dangerous in both the short-term and long-term. Of course there will be years of testing before these add-ons are released, but every brain could react differently, and we might not know the long-term dangers until it’s too late.

More importantly, the moral implications are huge. I can imagine various religious groups objecting to the “designer-brain” revolution on the grounds that it is “playing God”. Although I’m not religious myself, I can see where they’re coming from. We are, in effect, tinkering with thousands of years of evolution. Sure, there are many ways in which the human brain/body can be improved for the better. This, however, is a far beyond therapeutic applications.

For a start, the first to get their hands brains on these “add-ons” will surely be the rich. Instantly, we can see that those in power with modified super-brains could leave us all slaves to the authority. Politics would undoubtedly see a shift to the right. However, once these “add-ons” become more readily available, anyone will be able to buy them. At first, it’ll require surgery to install them; but soon enough, you’ll be able to install them yourself at home. Also, much like add-ons for Firefox, there could be a whole market of 3rd-party add-ons (“Make Me Happy V1.0″, designed by “dodgydesigner666″ on “BrainBay”, for example). Whether illegal or not, a black market of brain add-ons would undoubtedly lead to numerous deaths. Plus, your purchased add-ons could be riddled with viruses which upload your thoughts/personal informations to a crook’s (or government’s) inbox. This might be taking the computer-brain analogy a little too far, but you see my point.

Back to the ethical implications, the “designer-brain” revolution could lead to a break-down of society. People would be purchasing these add-ons to “better” themselves intellectually. This would lead to a social divide between those who can access the add-ons (who would become super-intelligent, with the highest-earning careers) and those who can’t (who, well, wouldn’t). People might also purchase these add-ons to improve their well-being. I’m not sure how to put this, but that just doesn’t seem right. There are reasons we don’t always feel great. Negative emotions can be a positive thing – they can help us to realise errors we may have made, and thus we can begin to work on amending them. With these add-ons, we may not feel the need to amend our mistakes, and they’d be repeated. For example, if a person experiences negative emotions as a result of failure, these emotions will (eventually) give them the motivation to make the change, and work on amending their mistakes and achieving to the best of their abilities. Also, to me, achieving to the best of our ability is something we should have to work for. If one person can purchase an add-on to increase their chances of success, then of course that’s unfair on those who haven’t  purchased the add-ons, whether due to choice or not.

This brings me onto my next point. If people are purchasing these add-ons and becoming super-intelligent, sooner or later people will realise that they need to buy them in order to keep up. It doesn’t become a choice anymore, it becomes an obligation to artificially modify your brain. There comes a time when free-will is out the window. With everyone installing “add-ons” into their brains, who’s to say their designers couldn’t be paid to design the add-ons so that their users can be manipulated, and their personal information shared with crooks/the government? We like to think that these things couldn’t, and wouldn’t, happen – but in reality, of course they can.

As Dieter Birnbacher, a philosopher at the University of Düsseldorf in Germany, says: 

"There are risks in technological self-improvement that could jeopardise human dignity. One potential problem arises from altering what we consider to be “normal”: the dangers are similar to the social pressure to conform to idealised forms of beauty, physique or sporting ability that we see today. People without enhancement could come to see themselves as failures, have lower self-esteem or even be discriminated against by those whose brains have been enhanced”, Birnbacher says.

He stops short of saying that enhancement could “split” the human race, pointing out that society already tolerates huge inequity in access to existing enhancement tools such as books and education.

Everybody will enhance theirself to fit what they believe to be correct – what they believe is best for them and society. However, this would drastically affect relations between different cultures – some cultures will be much more advanced than others, and cultures would be much more separated than they are today. This would not only jeopardise international relations, but also the global economy.

I realise that some of my points may be a little far-fetched, but nonetheless, you can see my point. This is all potentially possible.

The world as we know it is changing. (Can you keep up? Buy the latest add-on to inhibit your anxieties and denial and induce a zombified state of acquiescence)

What Your Facebook Account (doesn’t say) About Your Brain

http://www.psychologytoday.com/blog/games-primates-play/201203/what-your-facebook-account-says-about-your-brain

Although I couldn’t find the original papers, after reading this article, I just had to say (write) something. It is the biggest piece of tosh I have read in a while, courtesy of the field of “psychology”.

The article suggests that people who have more friends on Facebook have a larger orbital prefrontal cortex. It then goes on to say that this region of the brain is involved in “complex cognitive processes”, thus implying that using Facebook is a “complex cognitive process”. While I don’t dispute that it is often difficult to keep track of “who is sleeping with whom, who is making alliances with whom”, I would by no means consider this a complex cognitive process. Yet the article appears to suggest some sort of relationship between the number of friends a person has on Facebook and “complex” cognition, suggesting that those with more “friends” are somehow smarter than those with fewer. I would argue on the contrary – those who spend more time on Facebook and less time doing something worthwhile (like complex cognitive processes) are less likely to be smart, surely.

Just a further point, before I go on, the article claims:

“Establishing and maintaining many social relationships requires a great deal of brainpower.”

It may indeed, in reality. I wouldn’t, however, say this was true of “virtual” friends on Facebook. If a person has over 1000 friends, say, on Facebook, are they really keeping track of every single one of them? I highly doubt it.

The article goes on to say that research has shown that monkeys and apes who live in large social groups tend to have larger brain size, specifically of the prefrontal cortex. This is probably true, but again, I point out that Facebook is NOT the same as normal socialising. It definitely isn’t the same sort of socialising the monkeys in the research were doing. Thus, this comparison is invalid.

Furthermore, the article says that:

“…people with larger social networks (including the number of friends on Facebook) also have a larger amygdala (a brain region involved in emotion regulation).”

This seems to imply that people with more friends on Facebook are somehow more emotionally active. I would argue the exact opposite. From my experience, those with many friends on Facebook (>1000) are less emotionally active. They probably have a shallow knowledge of these “friends”, adding them after meeting them once at a party, and then never speaking to them again. How much do they actually communicate with these people, on an emotional level? Not much, I would argue. Besides, I would consider those with a large number of Facebook friends somewhat shallow, trying to show off their “popularity” to their 7364 “friends“.

I don’t know, maybe my dislike for Facebook has influenced my opinions, being a Twitter user myself. Personally, I don’t have many Facebook friends (around 100), since I feel this makes my experience on Facebook more personal. I have more meaningful virtual contact with my friends, rather than being bombarded with “relationship statuses” from people I barely know.

So, does this mean I have a smaller orbital prefrontal cortex? Am I less intelligent as a result? Or do I have a smaller amygdala? Am I less emotional?

I don’t think so.

Antioxidants Appear No Help for Alzheimer's

Antioxidant supplements don't appear to have an impact on cerebrospinal fluid (CSF) biomarkers related to Alzheimer's disease, a clinical trial determined.

The combination of vitamin E, vitamin C, and alpha-lipoic acid did not lower levels of the amyloid and tau proteins that make up the plaques and tangles seen in the brain with Alzheimer's disease, Douglas R. Galasko, MD, of the University of California San Diego, and colleagues found.

The combination did reduce CSF levels of the oxidative stress biomarker F2-isoprostane by 19% but raised a safety concern with faster decline in cognitive scores, they reported online in the Archives of Neurology.

The popular antioxidant coenzyme Q (CoQ) had no significant impact on any CSF measures in the Alzheimer's Disease Cooperative Study antioxidant biomarker trial.

Oxidative damage is widespread in the brain in Alzheimer's disease and contributes to neuronal damage, Galasko's group explained.

Some prior observational evidence has pointed to lower Alzheimer's risk with an antioxidant-rich diet, although prevention trials with supplements have had mixed results, they noted.

Their study included 78 adults with mild to moderate Alzheimer's randomly assigned to double-blind treatment over 16 weeks with the combination of 800 IU vitamin E, 500 mg vitamin C, and 900 mg of alpha-lipoic acid once a day; CoQ alone at a dose of 400 mg three times a day; or placebo.

Vitamins C and E act as antioxidants by controlling dangerous free radicals produced when oxygen reacts with certain molecules, while alpha-lipoic acid spurs production of many antioxidant enzymes in the body. CoQ is an antioxidant that helps protect mitochondria from oxidation.

Serial CSF specimens collected from 66 of the participants showed only small changes from baseline.

Beta-amyloid 42, which accumulates to forms plaques in the Alzheimer's brain, declined by 8 pg/mL from a baseline of 190 pg/mL with the antioxidant combination and by 15 pg/mL from a baseline of 185 in the CoQ group, but neither was a significant difference from placebo.

Tau protein, which forms neurofibrillary tangles in the brain with Alzheimer's, fell by 23 pg/mL with the antioxidant combination from a baseline of 123 and by 9 pg/mL from a baseline of 109 in the CoQ group, but again neither differed from changes with placebo.

Levels of tau phosphorylated at a specific site (P-tau181) likewise declined slightly over the study period for the two antioxidant groups but without a significant difference from placebo.

The one significant change was in CSF levels of the oxidative marker F2-isoprostane, which is stable oxidized arachidonic acid.

The vitamin C and E plus alpha-lipoic acid group saw a 7 pg/mL reduction in F2-isoprostane from a baseline of 38 over the 16 weeks of treatment (P=0.04). The other groups showed no change.

"It is unclear whether the relatively small reduction in CSF F2-isoprostane level seen in this study may lead to clinical benefits in Alzheimer disease," the group cautioned.

Cognition, measured with the Mini-Mental State Examination, didn't improve in any of the groups. In fact, the decline in scores appeared accelerated in the antioxidant combination group, with a change of -4.6 points over the 16 weeks compared with -2.3 to -2.4 in the other two groups.

The researchers highlighted that as a potential safety concern that needs further careful assessment if longer-term trials are considered. The antioxidants were otherwise well tolerated.

Function, as measured on the Alzheimer's Disease Cooperative Study Activities of Daily Living Scale, didn't change in any group.


http://www.medpagetoday.com/Neurology/AlzheimersDisease/31721

Galasko D, et al "Antioxidants for Alzheimer disease: a randomized clinical trial with cerebrospinal fluid biomarker measures" Arch Neurol 2012; DOI:10.1001/archneurol.2012.85.

Promising new research on Huntington's disease

Huntington's disease is a dreaded and debilitating congenital neurological disorder. There are little successful treatments and no cure. But a special type of brain cell forged from stem cells could help restore the muscle coordination deficits that cause the uncontrollable spasms characteristic of the disease.

"This is really something unexpected," Su-Chun Zhang, a University of Wisconsin-Madison neuroscientist said.

Zhang and his colleagues at the UW-Madison Waisman Center have learned how to make large amounts of GABA neurons from human embryonic stem cells, which they sought to test in a mouse model of Huntington's disease. The goal of the study, Zhang notes, was simply to see if the cells would safely integrate into the mouse brain. To their astonishment, the cells not only integrated but also project to the right target and effectively reestablished the broken communication network, restoring motor ability. It showed that locomotion could be restored in mice with a Huntington's-like condition.

What researchers found was intriguing, because GABA neurons reside in one part of the brain, the basal ganglia, which plays a key role in voluntary motor coordination. But the GABA neurons exert their influence at a distance on cells in the midbrain through the circuit fueled by the GABA neuron chemical neurotransmitter.

"This circuitry is essential for motor coordination," Zhang said, "and it is what is broken in Huntington patients. The GABA neurons exert their influence at a distance through this circuit. Their cell targets are far away."

That the transplanted cells could effectively reestablish the circuit was completely unexpected: "Many in the field feel that successful cell transplants would be impossible because it would require rebuilding the circuitry. But what we've shown is that the GABA neurons can remake the circuitry and produce the right neurotransmitter."

The study suggests that it may one day be possible to use cell therapy to treat Huntington's, but also because it suggests the adult brain may be more malleable than previously believed.

Zhang stresses that while the new research is promising; working up from the mouse model to human patients will take much time and effort. But for a disease that now has no effective treatment, the work could become the next best hope for those with Huntington's.

Brain-derived neurotrophic factor (BDNF)

Brain-derived neurotrophic factor, also known as BDNF, is a secreted protein that, in humans, is encoded by the BDNF gene. BDNF is a member of the "neurotrophin" family of growth factors, which are related to the canonical "Nerve Growth Factor", NGF. Neurotrophic factors are found in the brain and the periphery.

BDNF acts on certain neurons of the central nervous system and the peripheral nervous system, helping to support the survival of existing neurons, and encourage the growth and differentiation of new neurons and synapses. In the brain, it is active in the hippocampus, cortex, and basal forebrain—areas vital to learning, memory, and higher thinking. BDNF itself is important for long-term memory. BDNF was the second neurotrophic factor to be characterized after nerve growth factor (NGF).

Although the vast majority of neurons in the mammalian brain are formed prenatally, parts of the adult brain retain the ability to grow new neurons from neural stem cells in a process known as neurogenesis. Neurotrophins are chemicals that help to stimulate and control neurogenesis, BDNF being one of the most active. Mice born without the ability to make BDNF suffer developmental defects in the brain and sensory nervous system, and usually die soon after birth, suggesting that BDNF plays an important role in normal neural development.


Click here for a list of research involving BDNF. 

Mice Study Suggests Caution with Alzheimer’s Drugs

As baby boomers become seniors, researchers are aggressively searching for medications that can reduce the detrimental effects of Alzheimer’s disease. But a new study using mice suggests Alzheimer’s disease drugs now being tested in clinical trials may have potentially adverse side effects.

Northwestern University researchers discovered the drugs could act like a bad electrician, causing neurons to be miswired and interfering with their ability to send messages to the brain.

“Let’s proceed with caution,” said Robert Vassar, Ph.D., professor of cell and molecular biology at Northwestern University Feinberg School of Medicine. “We have to keep our eyes open for potential side effects of these drugs.”

Ironically, he said, the drugs could impair memory. The drugs in question are designed to inhibit BACE1, the enzyme Vassar originally discovered that promotes the development of the clumps of plaque that are a hallmark of Alzheimer’s. The BACE1 enzyme works by cutting up and releasing proteins that form the plaques. Thus, drug developers believed blocking the enzyme might slow the disease. However, in Vassar’s new study, he found BACE1 also has a critical role as the brain’s electrician. The enzyme maps out the location of axons, the wires that connect neurons to the brain and the rest of the nervous system, a process called axonal guidance.

Laboratory research involved studying genetically altered mice in which the BACE1 enzyme was removed. In doing this, Vassar discovered the animals’ olfactory system – used for the sense of smell — was incorrectly wired. The axons of the olfactory neurons were not wired properly to the olfactory bulb of the brain. The findings show the key role of BACE1 in axonal guidance. “It’s like a badly wired house,” Vassar said. “If the electrician doesn’t get the wiring pattern correct, your lights won’t turn on and the outlets won’t work.”

Studying the mechanism of the olfactory system is a good model for reviewing nerve or axonal wiring. If the axons aren’t being properly connected in the olfactory system, Vassar said, the problem likely exists elsewhere in the brain and nervous system. The hippocampus could be particularly vulnerable to BACE1 blockers, he noted, because its population of neurons is continually being reborn, which may play a role in forming new memories. The neurons need to grow new axons that in turn must connect them with new targets. Axonal guidance is a continuous need.

Despite the new findings, “It’s not all bad news,” Vassar noted. “These BACE1 blockers might be useful at a specific dose that will reduce the amyloid plaques but not high enough to interfere with the wiring. Understanding the normal function of BACE1 may help us avoid potential drug side effects.”

The findings, from the scientist whose original research led to the drug development, are published in the journal Molecular Neurodegeneration.

Researchers reveal how a single gene mutation interferes with the suppression of appetite, leading to obesity

The discovery offers clues about how to turn on brain sensitivity to leptin and insulin, hormones that turn off appetite

Washington, D.C. -- Researchers at Georgetown University Medical Center have revealed how a mutation in a single gene is responsible for the inability of neurons to effectively pass along appetite suppressing signals from the body to the right place in the brain. What results is obesity caused by a voracious appetite.

Their study, published March 18th on Nature Medicine's website, suggests there might be a way to stimulate expression of that gene to treat obesity caused by uncontrolled eating.

The research team specifically found that a mutation in the brain-derived neurotrophic factor (Bdnf) gene in mice does not allow brain neurons to effectively pass leptin and insulin chemical signals through the brain. In humans, these hormones, which are released in the body after a person eats, are designed to "tell" the body to stop eating. But if the signals fail to reach correct locations in the hypothalamus, the area in the brain that signals satiety, eating continues.

"This is the first time protein synthesis in dendrites, tree-like extensions of neurons, has been found to be critical for control of weight," says the study's senior investigator, Baoji Xu, Ph.D., an associate professor of pharmacology and physiology at Georgetown.

"This discovery may open up novel strategies to help the brain control body weight," he says.

Xu has long investigated the Bdnf gene. He has found that the gene produces a growth factor that controls communication between neurons.

For example, he has shown that during development, BDNF is important to the formation and maturation of synapses, the structures that permit neurons to send chemical signals between them. The Bdnf gene generates one short transcript and one long transcript. He discovered that when the long-form Bdnf transcript is absent, the growth factor BDNF is only synthesized in the cell body of a neuron but not in its dendrites. The neuron then produces too many immature synapses, resulting in deficits in learning and memory in mice.

Xu also found that the mice with the same Bdnf mutation grew to be severely obese.

Other researchers began to look at the Bdnf gene in humans, and large-scale genome-wide association studies showed Bdnf gene variants are, in fact, linked to obesity.

But, until this study, no one has been able to describe exactly how BDNF controls body weight.

Xu's data shows that both leptin and insulin stimulate synthesis of BDNF in neuronal dendrites in order to move their chemical message from one neuron to another through synapses. The intent is to keep the leptin and insulin chemical signals moving along the neuronal highway to the correct brain locations, where the hormones will turn on a program that suppresses appetite.

"If there is a problem with the Bdnf gene, neurons can't talk to each other, and the leptin and insulin signals are ineffective, and appetite is not modified," Xu says.

Now that scientists know that BDNF regulates the movement of leptin and insulin signals through brain neurons, the question is whether a faulty transmission line can be repaired.

One possible strategy would be to produce additional long-form Bdnf transcript using adeno-associated virus-based gene therapy, Xu says. But although this kind of gene therapy has proven to be safe, it is difficult to deliver across the brain blood barrier, he adds.

"The better approach might be to find a drug that can stimulate Bdnf expression in the hypothalamus," Xu says. "We have opened the door to both new avenues in basic research and clinical therapies, which is very exciting."

Deleting Nf1 Protein Quickens Relief from Depression

Eliminating a certain protein encourages the birth of new nerve cells and allows antidepressants to take effect more quickly, according to an animal study in The Journal of Neuroscience.

The normal role of the protein, called neurofibromin 1, is to prevent uncontrolled cell growth. The study suggests that treatment strategies developed to stimulate nerve cell birth may help treat depression more quickly, as current antidepressants typically take several weeks to take full effect.

Specifically, a particular section of the hippocampus produces new nerve cells during a process known as neurogenesis. This is made possible by specialized cells called neural progenitor cells (NPCs). Although previous research has shown that adult neurogenesis declines with age and stress, therapies known to alleviate symptoms of depression, such as exercise and antidepressants, increase neurogenesis.

A team of scientists, led by Luis Parada, PhD, of the University of Texas Southwestern, studied neurogenesis after removing the neurofibromin 1 (Nf1) gene from NPCs in adult mice. Results revealed that the removal of Nf1 increased the number and maturation of newborn nerve cells in the adult hippocampus.

Then, following seven days of antidepressant treatment, Nf1 mutant mice showed fewer depressive- and anxiety-like behaviors, whereas mice without the mutation took longer to show improvements.

“Our findings establish an important role for Nf1 in controlling neurogenesis in the hippocampus and demonstrate that activation of adult NPCs is enough to regulate depression and anxiety-like behaviors,” said study co-author Renee McKay, PhD, of the University of Texas Southwestern.

“Our work is among the first to demonstrate the feasibility of altering mood via direct manipulation of adult neurogenesis,” McKay added.

To determine if removing Nf1 leads to long-term changes in mice, the scientists ran 8-month-old mice through a variety of tests developed to measure anxiety- and depressive-like behaviors.

The mutant mice showed fewer anxious behaviors and also demonstrated resistance to the effects of chronic mild, unpredictable stress. Furthermore, even without antidepressants, removing Nf1 from NPCs in adult mice decreased symptoms of depression and anxiety.

“This study demonstrates that inducing neurogenesis is sufficient to produce antidepressant behavioral actions, and provides novel targets for therapeutic interventions,” said Ronald Duman, PhD, a neurogenesis expert from Yale University.

From PsychCentral.com

Scientists discover that specific antibodies halt Alzheimer's disease in mice

Antibodies that block the process of synapse disintegration in Alzheimer's disease have been identified, raising hopes for a treatment to combat early cognitive decline in the disease.

 

Alzheimer's disease is characterized by abnormal deposits in the brain of the protein Amyloid-ß, which induces the loss of connections between neurons, called synapses.

Now, scientists at UCL have discovered that specific antibodies that block the function of a related protein, called Dkk1, are able to completely suppress the toxic effect of Amyloid-ß on synapses. The findings are published today in the Journal of Neuroscience.

Dr Patricia Salinas, from the UCL Department of Cell & Developmental Biology, who led the study, said: "These novel findings raise the possibility that targeting this secreted Dkk1 protein could offer an effective treatment to protect synapses against the toxic effect of Amyloid-ß.

"Importantly, these results raise the hope for a treatment and perhaps the prevention of cognitive decline early in Alzheimer's disease."

Dkk1 is elevated in the brain biopsies of people with Alzheimer's disease but the significance of these findings was previously unknown. Scientists at UCL have found that Amyloid-ß causes the production of Dkk1, which in turn induces the dismantling of synapses (the connections between neurons) in the hippocampus, an area of the brain implicated in learning and memory.

In this paper, scientists conducted experiments to look at the progression of synapse disintegration of the hippocampus after exposure to Amyloid-ß, using brain slices from mice. They were able to monitor how many synapses survived in the presence of a specific antibody which targets Dkk1, compared to how many synapses were viable without the antibody.

The results show that the neurons that were exposed to the antibody remained healthy, with no synaptic disintegration.

Dr Salinas said: "Despite significant advances in understanding the molecular mechanisms involved in Alzheimer's disease, no effective treatment is currently available to stop the progression of this devastating disease."

She added: "This research identifies Dkk1 as a potential therapeutic target for the treatment of Alzheimer's disease."

Alzheimer's represents 60% of all cases of dementia. Alzheimer's Research UK estimates that in the UK the annual national cost of all the dementias is around £23 billion, which represents double the costs for cancer and 3-5 times the costs for heart disease and stroke. New studies predict an increase in the number of Alzheimer's cases of epidemic proportions.

The research was funded by Alzheimer's Research UK, the UK's leading dementia research charity, and the Biotechnology and Biological Sciences Research Council, UK.

Dr Simon Ridley, Head of Research at Alzheimer's Research UK, said: "We're delighted to have supported this study, which sheds new light on the processes that occur as Alzheimer's develops. By understanding what happens in the brain during Alzheimer's, we stand a better chance of developing new treatments that could make a real difference to people with the disease.

"Studies like this are an essential part of that process, but more work is needed if we are to take these results from the lab bench to the clinic. Dementia can only be defeated through research, and with the numbers of people affected by the condition soaring, we urgently need to invest in research now."

More information: 'The Secreted Wnt antagonist Dickkopf-1 is required for Amyloid B-mediated synaptic loss' is published in the Journal of Neuroscience.

"SpeechJammer" Invention Stops A Person Talking Mid-Sentence

Two researchers in Japan have invented a "SpeechJammer" device that can stop a person talking in mid-sentence, by just projecting back to them "their own utterances at a delay of a few hundred milliseconds". 


The device does not stop them talking permanently, it is just that they become so confused, they can't finish their sentence and begin to stutter or just shut up.

The two researchers are Kazutaka Kurihara, a media interaction research scientist at the National Institute of Advanced Industrial Science and Technology, and Koji Tsukada, an assistant professor at Ochanomizu University, and a researcher at JST PRESTO, a program that aims to "cultivate the seeds of precursory science and technology".

They describe their prototype SpeechJammer, and the results of some experiments, in a paper published on 28 February on arVix, an e-print service owned, operated and quality controlled by Cornell University.

The researchers say the device causes no physical discomfort to the interrupted speaker, and the effect stops as soon as they stop speaking.

The prototype SpeechJammer looks like a black cube about the size of a shoebox mounted on a shaft which acts as a handle. The box contains a direction-sensitive speaker, and on top of it is a direction-sensitive microphone.

On Kazutaka Kurihara's personal website there is a short video demonstrating the use of the device in two scenarios.

The first scenario shows a small group of people in an office, working at their computers, when one of them receives a call on her cellphone. The conversation begins to irritate the others, and then one of them decides to take action. He points the SpeechJammer at the irritating talker, interrupting her mid-sentence in her cellphone conversation, whereupon she appears confused, and then stops.

In the other scenario, a lecturer is talking and his lecture has run over time. Many of his students are looking quite bored and fed up and one of them takes the SpeechJammer, points it at the lecturer, and he trips over his own words and stutters, interrupting his flow.

The SpeechJammer works on the principle of Delayed Audio Feedback or DAF. There is a theory that when we speak, we use the sound of our own voice uttering the words to help us. But, if that "playback" is artificially delayed, it interrupts the cognitive processing that helps us maintain our flow. In fact, there is a theory that something akin to DAF is what happens to people who stutter, and it is known that artificially induced DAF can help reduce stuttering.

In their paper the researchers describe how they experimented with two speech contexts: one where the speaker was reading news out loud and another that was a "spontaneous monologue".

It appears that speech jamming is more successful, with this prototype, in the news out loud than in the monologue context, and also, it became obvious that it never works when meaningless sound is uttered, like when someone says "Ahhh" over a long period of time.

With reference to research on communication and decision making, Kurihara and Tsukada point out that applying rules and constraints on verbal contributions can change the properties of the discussion, and they also mention how "negative features" of speech can be "barriers toward peaceful communication". 

They propose that using the SpeechJammer to place a constraint on communication, by simply making "speech difficult for some people", it might "bring meaningful changes to communication patterns in discussions".

Such a system "points the way to promising future research relating to discussion dynamics," they write.

In their paper, the researchers focus very much on the science: the physics of the device and how it might be improved to deal with various parameters, plus the science of communication, and make no mention of the ethical and legal aspects of developing a machine that makes people stop talking.


Catharine Paddock PhD. (2012, March 2). ""SpeechJammer" Invention Stops A Person Talking Mid-Sentence." Medical News Today.

Lead Interferes With The Synthesis And Function Of Brain-Derived Neurotropic Factor, Derailing The Brain's Center For Learning

Exposure to lead wreaks havoc in the brain, with consequences that include lower IQ and reduced potential for learning. But the precise mechanism by which lead alters nerve cells in the brain has largely remained unknown. 


New research led by Tomás R. Guilarte, PhD, Leon Hess Professor and Chair of Environmental Health Sciences at Columbia University Mailman School of Public Health, and post-doctoral research scientist Kirstie H. Stansfield, PhD, used high-powered fluorescent microscopy and other advanced techniques to painstakingly chart the varied ways lead inflicts its damage. They focused on signaling pathways involved in the production of brain-derived neurotropic factor, or BDNF, a chemical critical to the creation of new synapses in the hippocampus, the brain's center for memory and learning. 

The study appears online in the journal Toxicological Sciences. 

Once BDNF is produced in the nucleus, explains Dr. Stansfield, it is transported as cargo in a railroad-car-like vesicle along a track called a microtubule toward sites of release in the axon and dendritic spines. Vesicle navigation is controlled in part through activation (phosphorylation) of the huntingtin protein, which as its name suggests, was first identified through research into Huntington's disease. By looking at huntingtin expression, the researchers found that lead exposure, even in small amounts, is likely to impede or reverse the train by altering phosphorylation at a specific amino acid. 

The BDNF vesicle transport slowdown is just one of a variety of ways that lead impedes BDNF's function. The researchers also explored how lead curbs production of BDNF in the cell nucleus. One factor, they say, may be a protein called methyl CpG binding protein 2, or MeCP2, which has been linked with RETT syndrome and autism spectrum disorders and acts to "silence" BDNF gene transcription. 

The paper provides the first comprehensive working model of the ways by which lead exposure impairs synapse development and function. "Lead attacks the most fundamental aspect of the brain - the synapse. But by better understanding the numerous and complex ways this happens we will be better able to develop therapies that ameliorate the damage," says Dr. Guilarte. 

Columbia University's Mailman School of Public Hea. (2012, March 2). "Lead Interferes With The Synthesis And Function Of Brain-Derived Neurotropic Factor, Derailing The Brain's Center For Learning." Medical News Today.

Restricting Enzyme Reverses Alzheimer's Symptoms In Mice

A study conducted by Li-Huei Tsai, a researcher at MIT, has found that an enzyme (HDAC2) overproduced in the brains of individuals with Alzheimer's, blocks genes needed to develop new memories. With this finding, the team were able to restrict this enzyme in mice and reverse symptoms of Alzheimer's. Results from the study are published in the February 29 online edition of Nature. 

Alzheimer's currently affects 5.4 million people in the United States. Findings from the study indicate that medications targeting HDAC2 could be a new techniques to treating Alzheimer's. Globally, the incidence of people with Alzheimer's is expected to increase two fold every two decades. Recently, President Barack Obama set a goal date of 2025 to find an effective treatment. 

According to Tsai, this goal could be achieved with the help of HDAC2 inhibitors, although it would probably take a minimum of at least a decade in order to develop and test such medications. Lead author of the report is Johannes Gräff, a postdoc at the Picower Institute. 

Tsai, director of the Picower Institute for Learning and Memory at MIT, explained: 

"I would really strongly advocate for an active program to develop agents that can contain HDAC2 activity. The disease is so devastating and affects so many people, so I would encourage more people to think about this."

Histone deacetylases (HDACs) are a class of 11 enzymes that control gene regulation by altering histones, which consist of highly alkaline proteins and are the chief protein components of chromatin. Histones act as spools around which DNA winds and play a role in gene regulation. HDACs transform a histone via a method called deacetylation. During this process, chromatin is packaged more tightly, making gens in that area less likely to be expressed. 

This effect can be reversed using HDAC inhibitors. These inhibitors open up the DNA and allow it to be transcribed. 

In prior investigations, Tsai has demonstrated the HDAC2 is an important regulator of memory and learning. In this study, the team found that restricting HDAC2 can reverse symptoms of Alzheimer's in rodents. 

The team discovered that HDAC2, yet no other HDACs, is overproduced in the hippocampus of mice with Alzheimer's symptoms. The hippocampus is a region in the brain where new memories are created. 

HDAC2 was most frequently found attached to genes involved in synaptic plasticity. Synaptic plasticity is the brains ability change the connection strength between two neurons, in response to new information, which is vital to making memories. 

In addition, the researchers found that those genes had significantly lower levels of acetylation and expression in the affected mice. 

Tsai explains: 

"It's not just one or two genes, it's a group of genes that work in concert to control different phases of memory formation. Which such a blockade, the brain really loses the ability to quickly respond to stimulation. You can imagine that this creates a huge problem in terms of learning and memory functions, and perhaps other cognitive functions."

Using short hairpin RNA, a molecule which can develope to attach to a carrier RNA, the team blocked HDAC2 in the hippocampi of mice with Alzheimer's symptoms. RNA is a molecule that delivers genetic instructions from DNA to the rest of the cell. 

The researchers found that reduced HDAC2 activity restarted histone acetylation, allowing genes needed for synaptic plasticity and other memory and learning processes to be expressed. They discovered that synaptic density increased considerably in treated mice, and that the rodents regained normal cognitive function. 

Tsai, said: 

"This result really advocates for the notion that if there is any agent that can selectively down-regulate HDAC2, it's going to be very beneficial."

In addition, the team evaluated postmortem brains of Alzheimer's patients and discovered increased levels of HDAC2 in the hippocampus and entorhinal cortex, which play vital roles in memory storage. 

According to Tsai, results from the study may explain why medications that remove beta-amyloid proteins from the brains of Alzheimer's patients have only provided modest, if any, improvements in human trials. 

In the brains of Alzheimer's patients, beta-amyloid proteins are known to clump. This clumping interferes with a type of cell receptor required for synaptic plasticity. Results from the study demonstrate that beta-amyloid also activates the generation of HDAC2, possibly initiating the restriction of memory and learning genes. 

Tsai explains: 

"We think that once this epigenetic blockage of gene expression is in place, clearing beta amyloid may not be sufficient to restore the active configuration of the chromatin." 

According to Tsai, HDAC2 inhibitors are appealing, as they could possibly reverse Alzheimer's symptoms even after the blockage is well-established, although significantly more medication development needs to be conducted before using such drugs in human trials. 

Tsai says: 

"It's really hard to predict. Clinical trials would probably be five years down the line. And if everything goes well, to become an approved drug would probably take at least 10 years." 

Although some researchers have tested some general HDAC inhibitors, not specific to HDAC2, in human trials as cancer medications, a more selective approach is required to treat Alzheimer's. Tsai explains: 

"You want something as selective as possible, and as safe as possible." 

Grace Rattue. (2012, February 29). "Restricting Enzyme Reverses Alzheimer's Symptoms In Mice." Medical News Today.

Activating The Visual Cortex Improves Our Sense Of Smell

A new study reveals for the first time that activating the brain's visual cortex with a small amount of electrical stimulation actually improves our sense of smell. 

The finding published in the Journal of Neuroscience by researchers at the Montreal Neurological Institute and Hospital - The Neuro, McGill University and the Monell Chemical Senses Center, Philadelphia, revises our understanding of the complex biology of the senses in the brain. 

"It's known that there are separate specialized brain areas for the different senses such as vision, smell, touch and so forth but, when you experience the world around you, you get a coherent picture based on information from all the senses. We wanted to find out how this works in the brain," says Dr. Christopher Pack, lead investigator at The Neuro. "In particular we wanted to test the idea that activation of brain regions primarily dedicated to one sense might influence processing in other senses. What we found was that electrically stimulating the visual cortex improves performance on a task that requires participants to identify the odd odor out of a group of three." This result is interesting because it shows, for the first time, that on a basic level the brain structures involved in different senses are really quite interconnected in everyone - more so than previously understood. 

"This 'cross-wiring' of senses has been described in people with synesthesia, a condition in which stimulation of one sense leads to automatic, involuntary experiences in a second sense, causing people to see the colour of numbers, or smell words, or hear odours for example, says Dr. Johan Lundstrom at Monell Chemical Senses Center. "Now this study shows that cross-wiring of the senses exists in all of us, so we could all be considered synesthetic to a degree." 

To examine the possibility that activating the visual cortex influences the sense of smell, people were tested on smell tasks before and after application of TMS, a non-invasive method of stimulating targeted brain areas. TMS, or transcranial magnetic stimulation, was directed towards the visual cortex using a protocol that had been previously shown by researchers at The Neuro to improve visual perception. TMS is already widely used in the treatment of certain disease symptoms, and because TMS alters brain activity in a targeted area, it provides a powerful test of the hypothesis that visual cortex activation changes olfactory perception. 

The results demonstrate that visual cortex activity is incorporated into the processing of smells, proving for the first time a cross-wiring of the visual and olfactory systems in the brain. Interestingly, the team did not find evidence for similar cross-wiring between olfactory and auditory systems. This suggests that vision may play a special role in binding together information from the different senses, a possibility that the researchers are currently exploring. In addition to Drs. Pack and Lundstrom, the research was carried out by Jahan Jadauji, a Master's student, and Jelena Djordjevic, a clinical neuropsychologist and neuroscientist, both at The Neuro. This collaboration between researchers and clinicians was made possible by The Neuro's integrated research institute and hospital. 


From Medical News Today

New drug offers bigger window to treat stroke

A DRUG which minimises brain damage when given three hours after stroke has proved successful in monkeys and humans.

A lack of oxygen in the brain during a stroke can cause fatal brain damage. There is only one approved treatment - tissue plasminogen activator - but it is most effective when administered within 90 minutes after the onset of stroke. Immediate treatment isn't always available, however, so drugs that can be given at a later time have been sought.

In a series of experiments, Michael Tymianski and colleagues at Toronto Western Hospital in Ontario, Canada, replicated the effects of stroke in macaques before intravenously administering a PSD-95 inhibitor, or a placebo. PSD-95 inhibitors interfere with the process that triggers cell death when the brain is deprived of oxygen.

To test its effectiveness the team used MRI to measure the volume of damaged brain for 30 days following the treatment, and conducted behavioural tests at various intervals within this time.

Monkeys treated with the PSD-95 inhibitor one hour after stroke had 55 per cent less damaged tissue in the brain after 24 hours and 70 per cent less after 30 days, compared with those that took a placebo. These animals also did better in behavioural tests. Importantly, the drug was also effective three hours after stroke (Nature, DOI: 10.1038/nature10841).

From NewScientist

Window installed into a live brain

For the first time, we can peer through a glass window into a live brain and see the individual neurons up close.

What if we had a glass window into the brain that lets us look inside? For the first time ever, a team of physicists, chemists and biologists has done just that. Led by a microscopy pioneer, they peered into a living mouse's brain using powerful technology.

"You can look into the brain and see a true neuron in action," said physicist Stefan Hell, who leads the Max Planck Institute of Biophysical Chemistry's Department of NanoBiophotonics. His team's achievement is described in the latest issue of the journal Science.

Hell is well-known in the field for inventing a super-resolution "stimulated emission depletion" or STED microscope in the 1990s that can distinguish among features in living samples on a scale so small that general wisdom said it would be impossible.

With that microscope, Hell and his colleagues at Max Planck can discern features down to 70 nanometers in the living brain -- four times beyond what had been the physical limit.

An electron microscope can show powerful levels of detail, but only on dead cells mounted and prepared just so. Recently Hell's team took a live mouse that had been genetically modified so its neurons produce a fluorescent agent. They placed the mouse under anesthesia, opened its skull, and replaced part of the bone with a glass window.

Then, the STED microscope lens was attached to the window so light could be focused on an upper layer of the live mouse's brain. Operating almost like an ultra-precise spotlight, the microscope only illuminated individual neurons carrying the fluorescent marker. All the other cells were dark, letting the neurons shine. (The mouse survived the procedure.)

The resulting images from the live brain have an unprecedented level of clarity, Hell said. Little protrusions with thin necks and a cup-like shape at the end can be seen on the neurons. These "dendritic spines" are the input, the place where a neuron receives signals from a synapse.

Since their technique requires a transgenic animal whose neurons fluoresce, Hell said the plan isn't to make such a window for any human brains. However, there is potential to use this approach for research into treating or even preventing certain neurological diseases.

"I think we can learn a lot about what's going wrong, for example, at a synapse in certain cases," Hell said. "That door is now slammed wide open because one can access a level of functionality, a level of detail that is really critical."

Next, Hell said he and his colleagues want to help neuroscientists use their method to learn about brain functions that are still poorly understood. They would also like scientists to advance research into potential treatments by studying malfunctioning synapses in live animal brains. As physicists, he added, his team will work on producing sharper images.

From Discovery News