Archive for the 'Neuroscience' Category

Apr 17 2014

Predicting Recovery from Coma

Published by under Neuroscience

I have been following the literature on using newer technologies (PET, fMRI, and quantitative EEG) to evaluate the brain activity of patients who appear unresponsive, loosely referred to as coma, or more generally disorders of consciousness. A new study, which I will get to below, adds an interesting element to the research.

For background, disorders of consciousness result from brain injury or disease that affects either the brainstem (needed for arousal) and/or both brain hemispheres. Level of consciousness is a continuum from drowsy to brain dead, but for the purposes of this discussion I am going to focus on three categories of chronic impairment of consciousness.

The first is called a minimally conscious state. In this condition patients are barely able to interact with their environment. They are mostly unresponsive, non-verbal, cannot care for themselves, but may respond to stimulation or show some interaction with their environment.

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Apr 03 2014

Change Blindness and the Continuity Field

Published by under Neuroscience

Change blindness is a fascinating phenomenon in which people do not notice even significant changes in an image they are viewing, as long as the change itself occurs out of view. Our visual processing is sensitive to changes that occur in view, but major changes to a scene can occur from one glance to the next without our noticing in many cases.

(See the color changing card trick for an example.)

One group of researchers believe they have a working hypothesis as to why our brains might have evolved in this way. Their idea is that the visual system will essentially merge images over a short period of time in order to preserve continuity – a process they call the continuity field. In essence our brains are sacrificing strict accuracy for perceived continuity.

This is in line with other evidence about how our brains work. Continuity seems to be a high priority, and our brains will happily fill in missing details, delete inconsistent details, and even completely fabricate information in order to preserve the illusion of a continuous and consistent narrative of reality.

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Mar 17 2014

Life Imitates Science Fiction

A man is in an extended coma after a traumatic injury. When he finally awakes from his coma he finds that he has brought something back with him from the darkness –  psychic powers. Yes, this is the plot of the 1983 Stephen King movie, The Dead Zone. It is also the alleged story of a 23 year old Southend student named Rob Ball.

Ball was assaulted and hit in the side of the head resulting in a two week coma. He had significant brain injury, and after waking from the coma he suffered from significant memory loss and needed extensive physical therapy in order to walk. Describing his injuries, he said:

 ”It feels like my head is going to blow up and I’m convinced I’m going to die all the time now, because it’s had such an impact on my life. I get deja vu all the time. I don’t know if it’s something to do with the head injury, but I keep thinking ‘I remember this before’, and think something is about to go wrong.”

Memory loss and headaches are typical symptoms of a traumatic brain injury. The deja vu is an interesting symptom – this is the phenomenon of feeling as if a current experience is familiar, as if it has happened before. We do not yet fully understand the neuroanatomical correlates and functional causes of deja vu, but we have some fairly compelling leads.

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Mar 03 2014

Your Baby Still Can’t Read

Published by under Neuroscience

Five years ago I wrote a blog post about the product, Your Baby Can Read. I concluded:

While the background concepts are quite interesting, the bottom line is that we have another product being marketed to the public with amazing claims and no rigorous scientific evidence to back them up. This product also falls into the broader category of gimmicky products claiming to make children smarter or more successful academically.

Anxious parents wanting to give their kids every advantage is a great marketing demographic, in that they are easily exploited. But like all gimmicky schemes promising easy answers to complex or difficult problems (weight loss, relationships, or academic success) in the end it is likely to be nothing but a costly distraction from more common sense approaches – like just spending quality time with your kids and giving them a rich and safe environment.  What such products often really provide is a false sense of control.

The comments quickly filled with parents who had used the system, which claims to teach even infants how to read, saying that the system worked for them.

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Feb 20 2014

Reality Testing and Metacognitive Failure

Published by under Neuroscience

Imagine coming home to your spouse and finding someone who looks and acts exactly like your spouse, but you have the strong feeling that they are an imposter. They don’t “feel” like your spouse. Something is clearly wrong. In this situation most people conclude that their spouse is, in fact, an imposter. In some cases this has even led to the murder of the “imposter” spouse.

This is a neurological syndrome known as Capgras delusion – a sense of hypofamiliarity, that someone well known to you is unfamiliar. There is also the opposite of this – hyperfamiliarity, the sense that a stranger is familiar to you, known as Fregoli delusion. Sufferers often feel that they are being stalked by someone known to them but in disguise.

Psychologists and neuroscientists are trying to establish the wiring or “neuroanatomical correlates” that underlie such phenomena. What are the circuits in our brains that result in these thought processes? A recent article by psychologist Philip Garrans explores these issues in detail, but with appropriate caution. We are dealing with complex concepts and some fuzzy definitions. But in there are some clear mental phenomena that reveal, at least to an extent, how our minds work.

The “reality testing” model discussed by Garran reflects the overall hierarchical organization of the brain. There are circuits that subconsciously create beliefs, impressions, or hypotheses. We also have “reality testing” circuits, specifically the right dorsolateral prefrontal circuitry, that examine these beliefs to see if they are internally consistent and also consistent with our existing model of reality. Delusions, such as Capgras and Fregoli, result from a “metacognitive failure” of these reality testing circuits.

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Jan 21 2014

A New Wrinkle on Change Blindness

I have discussed previously the phenomenon of change blindness – look at a picture which then winks off and then back on again. In between something may have changed. Would you detect it? Psychologist have found generally that people are pretty bad at detecting such changes.

Here is a nice demonstration of this phenomenon  by my colleague, Richard Wiseman. Just search for “change blindness” on Google and you will find many more.

Interestingly, if the change occurs without the picture winking off, in other words it occurs before our eyes, we are pretty good at detecting the change. Our attention is drawn to the change. But when the change occurs outside of our vision, we are bad at detecting that a change has occurred.

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Jan 06 2014

The Salinas Crop Circle

I can’t resist this excellent example of the human capacity for ad-hoc reasoning and pattern recognition. The Salinas Crop Circle was discovered in late December, and instantly became famous in the crop circle world. It is an example of a complex design, that begs to be interpreted.

Crop circle believers – those who think the designs that are often found drawn in various crops around the world (curiously following cultural lines) are the product of aliens trying to communicate in their abstruse way with humans, like to find meaning in the crop circles. This becomes an exercise in pattern recognition, as they are often trying to find meaning where none exists.

Here is one example. The author, assuming the crop circle is an alien communication, comes up with an elaborate interpretation. He believes it refers to comet ISON, which recently burned up on its journey around the sun. This itself is a good example of “retrodicting.” I would be more impressed if a crop circle predicted something yet to be discovered.

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Jan 02 2014

What Do You Want To Be When You Grow Up?

Published by under Neuroscience

I love windows into other times and places – especially those that offer insight into different world views. How did people really think and feel in the past? We know that standards and sensibilities change over time, but still it can be shocking to see an example of just how much things have changed.

My wife, born in 1964, was given such a window by her mother, who had dutifully saved many keepsakes from her childhood. One keepsake was a school journal, with one page dedicated to each year of grade school, starting with kindergarten. The template for each year is the same, which you can see to the right.

Take a look at the bottom of the form – it asks what they want to be when they grow up, and helpfully provides suggestions for each gender. Parents will playfully ask young children what they want to be when they grow up, knowing that they are far too young to make such decisions. The parents anticipate an answer that is cute, but also perhaps hope it will provide some insight into their child’s likes and personality.

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Dec 23 2013

Brain Scans and Psychics

In a trifecta of pseudoscience, Dr. Oz calls upon Dr. Amen to demonstrate (live on TV) how the Long Island Medium is real.

Where do I begin?

Dr. Oz has long ago abandoned any scientific legitimacy, not to mention self-respect. He has gone from giving basic medical advice, to promoting alternative quackery, and now he is just another daytime TV sellout, gushing over psychics. With Dr. Oz, however, it is all done with a patina of science.

The Medium

Theresa Caputo is just another fake psychic doing bad cold readings before audiences that have more of a desire to believe than apparent critical thinking skills. Her performance on Dr. Oz is fairly typical – she fishes with vague and high probability guesses, working multiple people at once, who then struggle to find some connection to what she is saying.

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Dec 09 2013

False Memory Fundamental

Published by under Neuroscience

It is now well established in psychological research that humans can form false memories – memories for events that never occurred. Further, these false memories are indistinguishable from genuine memories. Questions remain, however, about the neuroanatomical basis of false memories.

One potential window into this question are subjects with so-called “Highly Superior Autobiographical Memory” (HSAM).  HSAM itself is a fascinating topic – there are people who can remember many details about specific days in their past. You can ask them, what were you doing on December 9, 2012, and they can think back and tell you, “it was raining and I forgot to bring my umbrella, and I was late for work.” For details you can check, like whether or not it was raining on that day, their details check out.

A new study explores whether or not you can generate false memories in people with HSAM. This may tell us something about HSAM and false memories.

They used standard false memory tests. In one test you show the subject a list of words that all have a theme, for example words that all relate to sweet foods. You then show them a list of words and have them choose which words they can confidently remember from the previous slide. Among the new list of words is “sweet”, which was suggested but never listed in the original set of words (called a “lure word”). A significant number of people will have a false memory of seeing the word “sweet” on the previous slide.

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