Archive for the 'Neuroscience' Category

Aug 07 2020

Liver Fairies

Published by under Neuroscience

Liver scientists have a hypothesis – that the biological functioning of the liver, from the organism level down to the cellular level – is actually responsible for all the functions that appear to correlate with the liver. This is not a controversial hypothesis.

If, for example, those with severe liver disease, such as cirrhosis, lose the ability to make certain clotting factors, to regulate their blood glucose, to produce bile and digest fats, to metabolize drugs, and detoxify the blood, and to eliminate certain metabolic products from the blood, such as bilirubin, then those are all things that the liver actually does. In other words, the reason for the correlation is that liver function is the ultimate biological causation of all these things. Other parts of the body may be involved, but the liver is in the loop somewhere.

This hypothesis holds up very well. Liver disease reliably correlates with these downstream effects, and curing the liver or replacing it in severe cases reverses these effects. We can also culture liver cells in the lab and measure many aspects of their biological function, such as producing enzymes and metabolizing drugs. In many cases we have identified genes for liver enzymes, and can see that they are active in liver cells and not active in non-liver cells (mostly, there are always layers of complexity). We can even identify in some cases genetic mutations that produce altered function of those enzymes and produce specific diseases.

In fact the scientific hypothesis that the biological activity of the liver causes everything we see as liver function is so well established that it is taken as a given, and not questioned by any serious scientist. Over decades, countless labs and researchers doing countless studies have all relied upon this assumption, and it has worked out well.

This all may seem so obvious that it is silly to bother to point it out. But what if there were those who claimed that, in actual fact, some of what we think of as liver function is actually a manifestation of liver fairies. These are mystical entities that live in the liver. They are invisible and undetectable, but they carry out some of the functions we think of as liver function. The only reason that these functions correlate with the liver is because that is where the liver fairies live. They become unhappy when their home is not healthy, and stop doing some of their functions.

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Jul 20 2020

Mistaking Intention for Behavior

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Here’s another brain glitch that I know I do on a regular basis – confusing the intention to do a task with having actually completed the task. This is a type of false memory created by the intention itself. Albarracin et al have published a series of five experiments where they explore this phenomenon, which they claim is new to the published literature.

In there experiments people reported having completed a task that they only thought about doing but never actually did. If the task is routine this is more likely to happen. For example, if you take medication every day, you might remember taking the medication when you didn’t partly because you already have so many memories of actually taking the medication. Just having the thought – I need to take my medication – may be enough to trigger a false memory of taking it when you later think back about whether or not you took the medication. The experiments show that forming the intention to do the task increases the likelihood of forming such false memories.

The situation is also a factor. The closer the intention is to the actual task, the more likely it is you will form such a false memory of task completion. In other words, if you are sitting at your desk and you make a mental note that you have to do some task at your desk (such as sending an e-mail or signing a form), you may later remember having completed the task. This is more likely to occur than if the task involved traveling to a new location. They report:

Participants chose job candidates and either acted on the decision to hire them, generated an intention to hire them later or made a judgment that was irrelevant to the behavior.

Following a delay, participants were asked to report whether they had acted on the decision or simply intended to do so for each person they had seen.

“The methodology was carefully crafted to produce the necessary high level of errors we were studying, to keep irrelevant characteristics constant across conditions, and to systematically manipulate enactment versus intention,” said Albarracin, also a professor of business administration at Illinois. “If intentions play a causal role in producing misreports of behavior, misreports should be more common in the intention than the control condition.”

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Jul 14 2020

Imagining vs Seeing

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Try to conjure up a mental image of a bicycle (without referencing a picture). Better yet, try to draw a bicycle. Most people (75% or more) cannot draw an accurate bicycle from memory. There are a lot of layers here. First, people tend to grossly overestimate their specific or technical knowledge, especially of everyday objects and processes. I often like to challenge myself with the caveman thought experiment. If I suddenly found myself 20,000 years in the past living with pretechnological humans, how much technology could I bootstrap from my own knowledge? The answer is – surprisingly little (unless you are an expert in such things).

There is also the fact that we tend to overestimate the detailed accuracy of our memories. How many times have you seen a bike, and yet you cannot conjure up an accurate image of one in your brain. Perception itself is also limited – we tend to see what we pay attention to, and perception is highly filtered through our memory and expectation. I experienced this first hand when I started birding. Birds I had lived with my entire life suddenly became visible to me.

There is also the layer of – what is the neurological difference between imagining and seeing? Neuroscientists have already demonstrated that when we imagine or remember an image we use the same visual cortex as when we actually see an image. This makes sense because the visual cortex is organized in order to represent visual images, whether we are seeing, remembering, or imagining those images. In fact, there is probably little to no difference between remembering and imagining, but that is a topic for another day. What I want to explore further is a recent study that looked at the difference between seeing and imagining.

The researchers addressed this question in two ways. First they used a neural network designed to create and process images, and further designed to mimic the functional organization of the human brain. Specifically the neural network had basic or primary visual processing, and then more higher level visual processing. The researchers found that when creating an image the system activated the primary visual processing more diffusely but in less detail then when “seeing” an image. The researchers used this as a prediction and then studies human brains with fMRI to see if the computer model predicted human brain activity.

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Jul 09 2020

The Brain’s Filter

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If you have not seen this video of students passing basketballs around, watch it now before reading further.

The now famous video, from Simons 1999, is a demonstration of inattentional blindness. There is no trick here, just a demonstration of normal brain functioning. When we are focusing our attention on one type of stimuli we can filter out “distracting” stimuli that doesn’t fit the parameters. In the basketball example you were instructed to pay attention to the students in white, so your brain flagged the students in black as distracting information. The gorilla, which is also black, was therefore filtered out as well (for about 40% of subjects).

Interestingly, often people take pride in having noticed the gorilla, but this is not necessarily a manifestation of having better attention. In fact noticing the gorilla, if anything, might mean you are more distractable and have worse attention (it also can be mostly random chance). The brain is supposed to filter out extraneous stimulation, otherwise we would not be able to function. Those suffering from traumatic brain injury, for example, often complain that they cannot filter out distracting sensory stimuli, so they find noisy or busy environments (like crowds) very uncomfortable. They may not be able to focus on work unless they are in a distraction-free environment. It’s impairing.

In other words – in the experimental setup of the students passing around the basketballs, not noticing the gorilla was an active step of filtration by the brain, not a failure to notice the gorilla. Such inattentional blindness is now experimentally well-established. Actually (interesting story) the first experiments demonstrating inattentional blindness were in 1959, but they were accidental. Paranormal researcher Tony Cornell published a couple of experiments regarding people noticing a subject wearing a ghost costume, and found that surprisingly few people did. He interpreted the results incorrectly, as evidence that a person in a sheet lacked the psi phenomena of a “real” ghost, but now we can look back and clearly see inattentional blindness at work.

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Jun 04 2020

fMRI Researcher Questions fMRI Research

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This is an important and sobering study, that I fear will not get a lot of press attention – especially in the context of current events. It is a bit wonky, but this is exactly the level of knowledge one needs in order to be able to have any chance of consuming and putting into context scientific research.

I have discussed fMRI previously – it stands for functional magnetic resonance imaging. It uses MRI technology to image blood flow to different parts of the brain, and from that infer brain activity. It is used more in research than clinically, but it does have some clinical application – if, for example, we want to see how active a lesion in the brain is. In research it is used to help map the brain, to image how different parts of the brain network and function together. It is also used to see which part of the brain lights up when subjects engage in specific tasks. It is this last application of fMRI that was studied.

Professor Ahmad Hariri from Duke University just published a reanalysis of the last 15 years of his own research, calling into question its validity. Any time someone points out that an entire field of research might have some fatal problems, it is reason for concern. But I do have to point out the obvious silver lining here – this is the power of science, self-correction. This is a dramatic example, with a researcher questioning his own research, and not afraid to publish a study which might wipe out the last 15 years of his own research.

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May 28 2020

Confidence Drives Confirmation Bias

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Human thought processes are powerful but flawed, like a GPS system that uses broken algorithms to lead you to the wrong destination. Psychologists study these cognitive biases and heuristic patterns of thought to better understand these flaws and propose possible fixes to mitigate them. To a large degree, scientific skepticism is about exactly that – identifying and compensating for the flaws in human cognition.

Perhaps the mother of all cognitive biases is confirmation bias, the tendency to notice, accept, and remember information that confirms what we already believe (or perhaps want to believe), and to ignore, reject, or forget information that contradicts what we believe. Confirmation bias is an invisible force, constantly working in the background as we go about our day, gathering information and refining our models of reality. But unfortunately it does not lead us to accuracy or objective information. It drives us down the road of our own preexisting narratives.

One of the things that makes confirmation bias so powerful is that it gives us the illusion of knowledge, which falsely increases our confidence in our narratives. We think there is a ton of evidence to support our beliefs, and anyone who denies them is blind, ignorant, or foolish. But that evidence was selectively culled from a much larger set of evidence that may tell a very different story from the one we see. It’s like reading a book but making up your own story by only reading selective words, and stringing them together in a different narrative.

A new study adds more information to our understanding of confirmation bias. It not only confirms our selective processing of confirming information, it shows that confidence drives this process. So not only does confirmation bias lead to false confidence, that confidence then drives more confirmation bias in a self-reinforcing cycle.

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May 25 2020

Can We See Personality?

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Is someone’s basic personality type written on their face? This is an interesting question, that research has not definitively answered. A new study uses AI to add one more piece of information, suggesting that the answer is – maybe, sort of.

Let’s start with a technical definition of personality:

“Personality refers to individual differences in characteristic patterns of thinking, feeling and behaving.”

It is uncontroversial that different people have different personality traits, although there are different schemes for how to divide up all the different recognizable personality traits people might display. One of the more accepted schemes is OCEAN (the big five) – Openness, Conscientiousness, Extroversion, Agreeableness, and Neuroticism. This does not capture every aspect of one’s personality, nor the rich background of experience and culture that helps mold our behavior, but it does seem to capture something fundamental about how humans vary.

Far more controversial is whether or not there are different personality types, meaning a suite of personality traits that tend to go together. There are many tests based on the assumption that people can be sorted into a small number of different personality types, but none of them have established validity. The best evidence we have so far, in my opinion, does not support the notion of personality types in any meaningful way.

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May 21 2020

Localizing Executive Function

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Where in the brain is a specific ability located? This is a more complex question than it may at first seem, mainly because we first have to define each specific ability. Some are obvious, like the ability to voluntarily move your right hand. The motor strip in the cortex physically maps to the body, and it is relatively easy to correlate a specific part of the brain to weakness of any specific body part. But even something as simple as motor control has many layers – other parts of the brain that modify control, allowing for smooth coordinated movement, for example.

Arguably the most difficult functions to localize in the brain are the more abstract ones, like executive function. This is extremely challenging partly because we don’t really know what those functions are at their most fundamental level. We can learn what behaviors they allow, but how? What is actually happening in the brain when you make a decision, for example?

Some of these more abstract functions are also difficult to study because they may be bilateral, meaning that the same structure on both sides of the brain contribute to the function. Therefore a lesion taking out one side won’t necessarily cause any deficits. Motor control, by contrast, is unilateral, so one single lesion causes an obvious deficit. This is important because studying lesions is one major way neuroscientists localize brain function – wait for it to break and than see what doesn’t work. Historically such lesion studies have been the most important method for mapping the brain.

Today we have other methods, such as imaging the brain functioning (fMRI), mapping electrical activity with EEG, and even temporarily influencing brain function with electrical or magnetic stimulation. This data (the first two methods, anyway), however, is mostly correlational. It can still be powerful, but a lesion is helpful in confirming causation.

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May 15 2020

Stimulating the Visual Cortex

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For adults who had vision but then lose it due to eye disease or damage to the optic nerve, their visual cortex is still intact. It is deprived if input, but is theoretically capable of functioning normally to create images. The ultimate technological expression of this potential would be something like the visor of Geordi La Forge – a device that can see (even in frequencies and particles humans cannot normally see) and transfer that information to the visual cortex. Obviously we are a long way away from any such technology, but we have taken the first baby steps in that direction, including a recent study which makes one tiny advance (but more on that shortly).

Early research into this approach involved animals and simply tried to determine if the monkeys could “see” the stimulation. Often simple behaviors, like moving their eyes, were used to see if the stimulation was having any effect. Some of the research also comes from trying to map the visual cortex, not necessary allow the blind to see. This research has been encouraging, because it shows that the primary visual cortex is arranged in a way to reflect the images it sees (so-called retinal mapping). The neurons, in short, are like a bitmap of an image. So if you stimulated a circle of neurons in the primary visual cortex, subjects would see a circle.

Of course there is more to vision than the primary visual cortex. A lot of processing occurs in the nerves  and pathways carrying information to the cortex. After the basic image is formed it is then sent to higher visual cortical areas for further processing, so a two-dimensional image is given shape, shading, movement, distance, three-dimensionality, and ultimately meaning. But hopefully we wouldn’t need to worry about all that higher levels of processing because once the image is presented to the primary visual cortex, the rest should take care of itself.

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May 05 2020

The Psychology of Buying More

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When I was in college I had just finished a course on social psychology (certainly one of the most memorable courses I took in college), and while back home I was visiting with my then girlfriend. When I arrived they were in the middle of dealing with a door-to-door textbook salesperson. That’s right – the product was a mathematics textbook that combined the K-12 curriculum into one giant tome. My girlfriend’s parents asked my advice, so I sat down to listen to the spiel.

The salesman was sitting in their living room, sitting on one side while the family members were all opposite. He had a velcro cast on one of his legs (the kind that can be removed and put back on) and was sporting crutches. His tactic was largely highlighting some feature of the book, then asking someone specifically if they thought that feature would be helpful. “Do you think it would be helpful to all this information in one location?” The answer, of course, was always yes. He mentioned that a neighbor down the street had just purchased the book for their high school student.

It was a fascinating experience for me, because I had just learned about all of the techniques the salesman was using. He was garnering sympathy with the cast. Using peer pressure by mentioning their neighbors. Getting them to agree that the product was useful, so they would feel inconsistent if they then decided not to buy. He positioned the family all on one side so they could not make eye contact with each other during his presentation.

After the pitch, while the book salesman was still waiting in the living room, I told the parents not to buy the book. I explained all the manipulative techniques he was using. Further, they simply did not need the book, and it was expensive. They understood, but bought the book anyway. They felt he had invested so much time in the sales visit they could not say no. His emotional manipulations worked – even when they knew they were being manipulated. It would have been simply too socially awkward to send him away with no sale.

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