Archive for the 'Neuroscience' Category

Jul 29 2014

Reward and Punishment in the Brain

Published by under Neuroscience

In a recent study, scientists looked at the brain with high resolution fMRI scanning while they showed subjects pictures. Following each picture was a painful electric shock, or a money reward, or no response, or a random response. Subjects quickly learned which pictures would be followed by which stimuli – positive, negative, neutral, or unpredictable.

Scientists do this sort of thing not because they like to torture people but to study the brain’s response. In this case they were particularly interested in a small deep structure called the habenula. What they found, for the first time in humans but consistent with prior animal research, is that the habenula would light up when subjects saw a picture that would be followed by a shock, and the activity in the habenula increased the more certain the subjects were that negative stimuli were following.

The researchers conclude that the habenula is a critical structure for the processing of negative stimuli, in fact it seems to be the hub of the neural network involved in learning to anticipate negative stimuli.

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Jul 24 2014

Sleep and False Memory

Published by under Neuroscience

When someone looks at me and earnestly says, “I know what I saw,” I am fond of replying, “No you don’t.” You have a distorted and constructed memory of a distorted and constructed perception, both of which are subservient to whatever narrative your brain is operating under.

One of the more dramatic aspects of memory distortion is false memories. These can be completely fabricated memories that are indistinguishable from genuine memories. False memories can involve small details, or entire scenarios. One way to fabricate false memories is with suggestion – just suggesting to someone a detail of an experience they had may cause them to incorporate that detail into their memory of the experience.

The apparent reason for this is that our brains appear to favor consistency over accuracy. Memories are updated to bring them into line with our current knowledge. If we are told that the person was wearing a blue jacket, then our memory might change so that it is consistent with what we now believe to be true.

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Jul 17 2014

European Commission Human Brain Project Hubbub

Published by under Neuroscience

In 2013 the European Commission awarded $1.3 billion to a project to simulate the human brain in a supercomputer. While everyone is excited about this prospect, and welcomes the infusion of cash, recently the project has come under public criticism.

More than 180 neuroscientists signed an open letter criticizing the way the project is being managed. The letter states:

“We believe the HBP is not a well-conceived or implemented project and that it is ill suited to be the centerpiece of European neuroscience.”

There appear to be two main points to the criticism – the first is that the money is largely going to computer scientists to create the software that will simulate the human brain. The neuroscientists complain that while the project is being sold to the public as a neuroscience project, in reality it is an IT project.

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Jun 17 2014

Deepak Challenge to Skeptics

Deepak Chopra doesn’t appear to like skeptics much, or understand them. He just put out a YouTube video challenging ”Randi and his cronies” to his own fake version of the million dollar challenge.

All we have to do, apparently, is make 50-100 years of scientific advance in neuroscience in a single peer-reviewed paper. I’ll get started on that right away.

Actually, even that probably would not be sufficient. The whole point of pseudoscientific goal-post moving is to keep forever out of reach of current scientific evidence. It doesn’t matter how much progress science makes, there will always be gaps and limitations to our knowledge. Chopra lives in the gaps.

Here is his exact challenge:

Dear Randi: Before you go around debunking the so-called “paranormal,” please explain the so-called “normal.” How does the electricity going into the brain become the experience of a three dimensional world in space and time. If you can explain that, then you get a million dollars from me. Explain and solve the hard problem of consciousness in a peer-reviewed journal, offer a theory that is falsifiable, and you get the prize.

The challenge is absurd because it is completely undefined. “Explain” to what degree? Science often advances by developing theories that are progressively deeper. Obviously we can explain consciousness on some level, and just as obviously Chopra would not accept that level as sufficient, but he gives absolutely no indication of how much deeper an explanation he would require.

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Jun 06 2014

PETA Responds

Last week on Science-Based Medicine I wrote an article about the embrace by PETA (people for the ethical treatment of animals) of pseudoscience – in this case they are engaging in a fearmongering campaign linking dairy products to the risk of autism or increasing the severity of autism.

Yesterday I received an e-mail from PETA, essentially doubling down on their prior embrace of pseudoscience:

Dear Steven,

I want to follow up on your story last week about PETA’s campaign that points out how a dairy-free diet may help children with autism. PETA’s website and campaign serve to provide parents with potentially valuable information, albeit mostly anecdotal, from families’ findings—for example, just this week, the editor of Autism Eye magazine, Gillian Loughran, who has a 14-year-old son with autism, contacted us in support of our campaign and wrote a letter to the editor on our behalf (see below). Until such time as there is a large study into whether there is a dairy-autism link (and one we hope will not be funded by the dairy industry), it seems unwise to overlook a growing body of anecdotal information supporting that removing dairy and gluten from the diet of a child with autism may improve the child’s sleep, behavior, and concentration. We hope this letter will change your mind about PETA’s campaign—or, at least, that you will share this letter with your readers so that they can arrive at an informed opinion.

Thank you for your time.

Best regards,

Heather 

There are multiple problems with this position.

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Jun 05 2014

Preventing Memory Impairment

Published by under Neuroscience

One of the more common complaints I see in my clinical practice is subjective memory impairment (SMI) – the perception of poor concentration and short term memory. SMI is distinguished from full-blown dementia in that the mental status exam and diagnostic tests are normal, but the symptoms can still be significant.

Once an underlying disease or specific pathology has been ruled out, the working diagnosis for SMI is that it is functional, meaning that it is a symptom of some process that is temporarily impairing brain function but not causing permanent or progressive brain damage. The task then becomes to identify any lifestyle factors that may be causing SMI.

A recent study published in PLOS One sheds further light on such risk factors. The authors conducted a survey of 18, 614 people of various ages and asked questions about memory and behaviors. They found:

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May 27 2014

The Brain Is Not a Receiver

Whenever the discussion of a dualist vs materialist model of the mind comes up, one common point made to support the dualist position (that the mind is something other than or more than just the functioning of the brain) is that the brain may not be the origin of the mind, but rather is just the receiver. Often an explicit comparison is made to radios or televisions.

The brain as receiver hypothesis, however, is wholly inadequate to explain the relationship between the brain and the mind, as I will explain below.

As an example of the brain-receiver argument, David Eagleman writes in his book Incognito:

As an example, I’ll mention what I’ll call the “radio theory” of brains. Imagine that you are a Kalahari Bushman and that you stumble upon a transistor radio in the sand. You might pick it up, twiddle the knobs, and suddenly, to your surprise, hear voices streaming out of this strange little box. If you’re curious and scientifically minded, you might try to understand what is going on. You might pry off the back cover to discover a little nest of wires. Now let’s say you begin a careful, scientific study of what causes the voices. You notice that each time you pull out the green wire, the voices stop. When you put the wire back on its contact, the voices begin again. The same goes for the red wire. Yanking out the black wire causes the voices to get garbled, and removing the yellow wire reduces the volume to a whisper. You step carefully through all the combinations, and you come to a clear conclusion: the voices depend entirely on the integrity of the circuitry. Change the circuitry and you damage the voices.

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May 02 2014

Framing Bias

Published by under Neuroscience

Let’s say you need a surgical procedure and the surgeon tells you there is a 98% survival rate with the procedure. How would you feel about that? What if she told you there was a 2% mortality rate? Would you feel the same way? Probably not, according to years of psychological research.

This is known as framing bias, just one more of the many ways in which our brains are biased in the way we evaluate information. The two scenarios above are identical, but statistically people will make different decisions based upon how the information is framed. We generally respond better to positively framed information (98% survival) than to negatively framed information (2% mortality).

The framing effect is often exploited by those who are deliberately trying to manipulate our reactions. Politicians, for example, can talk about employment rates or unemployment rates. Events can give you an early-bird discount or a late registration penalty. Products can have 4% fat or be 96% fat free.

Framing is another way in which we construct our picture of realty, by deciding what information is important.

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Apr 29 2014

Neuromorphic Computing

Published by under Neuroscience

Kwabena Boahen and other engineers at Stanford University announce that they have developed a computer chip modeled after the human brain. They call the technology “neuromorphic” and their current device the neurogrid. They say it can simulate 1 million neurons in real time, a feat that would otherwise require a super computer.

The idea is that the human brain is much more powerful and energy efficient than our current computers. A mouse brain can process information 9,000 times faster than a computer simulation of its functions, while using much less energy.

The article does not explicitly state it, but I suspect these numbers are for virtual simulations – in other words, we are not building mouse brain circuits in silicon, we are using standard digital computer to simulate the mouse circuits in software. Virtual simulations are much less efficient (about an order of magnitude) than dedicated circuits.

Even still, the neurogrid looks like a huge advance even over building dedicated brain circuits using standard digital chip technology.

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Apr 22 2014

Motivated Memory

Published by under Neuroscience

I have had the following experience many times, and so I suspect that it is a near-universal experience. You are in a heated conversation with one or more other people who have differing opinions on the topic of discussion. Perhaps it’s just a fight over personal matters. After the heat has died down and calmer emotions prevail, you try to come to some sort of resolution about the prior conversation. Such efforts, however, are complicated by the fact that everyone has a very different memory of the conversation you just shared.

A related experience that is also common occurs when discussing a topic about which there is disagreement (such as politics), and then revisiting the topic weeks or months later. Again, everyone has a different memory of the prior discussion, including which facts were established. It’s almost as if the previous conversation had not taken place.

It’s as if everyone edits their memories to fit their existing narrative. In this way, memory can be a very dangerous thing – it gives us a false confidence in our current beliefs and attitudes. We believe the facts support our position. However, we often choose our facts based on our narrative, rather than craft a narrative based upon facts.

We tend to easily see this process in others, but of course often fail to see it in ourselves.

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