Archive for the 'Neuroscience' Category

Dec 14 2021

Zoom Fatigue

Published by under Neuroscience

I love the fact that three years ago no one would have any idea what the title of this post meant, and now pretty much everyone does. It’s a testament to the rapid pace of cultural change driven by digital technology. Over the last two years of the pandemic many people have become familiar with the app Zoom, which is a video conferencing app that was in the right place at the right time with the right features. There are, of course, other apps but Zoom clearly dominated the market.

Regardless of the app being used, video conferencing for many displaced school, lectures, work meetings, and even social gatherings. For those not already familiar with such technology it was a rapid education (Dude, you’re on mute!). Twenty-five percent of my patient visits are now over zoom, so I get to see the full spectrum of comfort with the technology, although overall it is definitely improving.

Many people, including Julie Boland who is a professor of psychology and linguistics, noticed that video conferencing can sometimes be more fatiguing than in person conversations. So she decided to research why that might be. Her initial hunch is that it might have something to do with the short delay in transmission times throwing off the natural rhythms of human conversation. Previous research had identified four contributors to Zoom fatigue – intense and slightly misaligned eye contact, being on camera, limited body movement, and lack of nonverbal communication.

As we learn to optimize the use of video conferences some of these factors are easily dealt with. For example, you can simply turn off your camera when you are not the speaker. This saves some digital throughput and energy as well, and means you don’t have to be on-camera the whole time, even when just listening. The misaligned eye-contact can be mitigated by placing the video window as close to your camera as possible, and adjusting the camera so that you are well-framed for others. Also, pure audio conversations can be just as good, and the video does not always add anything. I have been doing this for over 16 years, with five people recording a long podcast every week using just audio. You adapt.

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Nov 09 2021

Brain Stimulation for Cognitive Control

Published by under Neuroscience

A newly published study presents a proof-of-concept for using deep brain stimulation controlled with artificial intelligence (AI) in a closed-loop system to enhance cognitive control, suggesting it might be effective for a number of mental illnesses. That’s a lot to unpack, so let’s go back to the beginning. The most fundamental necessary to understand what is going on here is that your brain is a machine. It’s a really complicated machine, but it’s a machine none-the-less, and we can alter the function of that machine by altering its physical state.

This may seem obvious, but actually people are generally psychologically biased against this view. This may, in fact, be a consequence of brain function itself, which evolved to create a seamless stream of consciousness, an illusion of self unaware of all the subconscious processes that make up brain function. This is why we tend to interpret people’s behavior in terms of personality and conscious choice, when in fact much of our behavior is a consequence of subconscious processes. We are also biased to believe that people can think or will-power their way out of mental illness.

The more we understand about how the brain functions, however, the more it becomes apparent that the brain is just a glitchy machine, and lots can go wrong. Even when functioning within healthy parameters, there are many trade-offs in brain function, with strengths often coming at the price of weaknesses. We need to look out for our own interests, for example, but this comes at the price of anxiety and paranoia. But there are some brain functions that are so basic they are almost universally useful, and impairment of them can cause of host of problems. One such basic brain function is called cognitive control, which is essentially the ability to determine what thoughts and actions will be the focus of your brain’s attention.

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Oct 11 2021

Neurofeedback Headbands for Stress Reduction

Published by under Neuroscience

A recent BBC article discusses the emergence of products designed for neurofeedback to aid in stress reduction. The headline asks, “Smart headbands claim to make people calmer. Do they work?” However, the article does not really answer the question, or even get to the heart of the issue. It mostly provide anecdotes and opinions without putting the technology into a clear context. The article focuses mainly on the use of such devices to allegedly improve sports performance.

There are a few premises on which the claims made for such devices are based, varying from well established to questionable. One premise is that we can measure “stress” in the brain using an electroencephalograph (EEG) to measure the electrical activity in the brain. This claim is mostly true, but there is some important background necessary to understand what this means. First, we need to define “stress”. Functionally when researchers are talking about mental stress they mean one of two things, either the stress that results from an immediate physical threat, or the mental stress that results from engaging in a challenging mental task (like doing math in your head while being distracted). For practical purposes the research on EEGs and mental stress use the challenging mental task model.

It his, however, a good representation of stress generally? It is a convenient research paradigm, but how generalizable it is to mental stress is questionable. It can result in objective measures of physiological stress, such as secretion of stress hormones, which is partly why it’s convenient for research and not unreasonable, but it is only a representation of mental stress and might not translate to all “stressful” situations (like sports).

Can EEGs measure this type of mental stress? Yes – a relaxed mind with eyes closed produces a lot of regular alpha waves. A more active mind (and one with eyes open) produces more theta waves and chaotic brainwave activity. EEGs can therefore tell the difference between relaxed and active. How about not just active but stressed? That is trickier, but there are studies which appear to show some statistical differences in the wave patterns regionally with mental stress. So the premise that EEGs can measure certain kinds of mental stress is reasonable, but not as simple as often implied. This also does not necessarily mean that commercial devices claiming to measure EEG markers of stress work.

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Oct 08 2021

Hacking the Brain to Treat Depression

Published by under Neuroscience

A new study published in Nature looks at a closed loop implanted deep brain stimulator to treat severe and treatment resistant depression, with very encouraging results. This is a report of a single patient, with is a useful proof of concept.

Severe depression can profoundly limit one’s life, and increase risk for suicide (affecting 300 million people worldwide and causing most of the 800,000 annual suicides). Depression, like many mental disorders, is very heterogenous, and is therefore not likely to be one specific disorder but a class of disorders with a variety of neurological causes. It also exists on a spectrum of severity, and it’s very likely that mild to moderate depression is phenomenologically different fromĀ  severe depression. Severe depression can also be in some cases very treatment resistant, which simply means our current treatment options are probably not addressing the actual brain function that is causing the severe depression. We clearly need more options.

The pharmacological approach to severe depression has been very successful, but still not effective in all patients. For “major” depression, which is severe enough to impact a person’s daily life, pharmacological therapy and talk therapy (such as CBT – cognitive behaviorial therapy) seem to be equally effective. But again, these are statistical comparisons. Treatment needs to be individualized.

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Oct 07 2021

Map of the Primary Motor Cortex Published

Published by under Neuroscience

By now, especially if you are a regular reader here, you have probably heard of the connectome project, an attempt to entirely map the cells and connections of the human brain. This goal is actually comprised of multiple initiatives, one of which is the Brain Research Through Advancing Innovative Neurotechnologies (BRAIN) funded by the NIH. They have now published in Nature their first major result – a map of the mammalian primary motor cortex (technically a “multimodal cell census and atlas of the mammalian primary motor cortex”).

The goal of this initiative is to break the brain down into its constituent parts and then see how they all fit together. This begins with knowing all the different brain cell types, and this is part of the string of publications they have produced. The brain contains about 160 billion cells, with 87 billion neurons and the rest astrocytes (which provide supporting and modulating functions). There are many different kinds of neurons, with significant functional differences. Neurons differ in their structure and their chemistry.

The basic structure of a neuron is a cell body with dendrites (hair-like projections) for incoming signals and axons (longer projections) for outgoing signals. But the shape, number, and arrangement of dendrites and axons can vary considerably, and reflect their function, which relates to the pattern of connections the neuron makes. Neurons also differ in terms of their biochemistry – which neurotransmitters do they make, and which neurontransmitter receptors they have. Some neurotransmitters like glutamate are activating (make neurons fire faster) and others like GABA are inhibitory (make them fire slower or not at all).

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Sep 28 2021

Light Beads Microscopy To Image Brain Activity

Published by under Neuroscience

The current estimate is that the average human brain contains 86 billion neurons. These neurons connect to each other in a complex network, involving 100 trillion connections. The job of neuroscientists is to map all these connections and to see how they work – no small task. There are multiple ways to approach this task.

At first neuroscientists just looked at the brain and described its macroscopic (or “gross”) anatomical structures. We can see there are different lobes of the brain and major connecting cables. You can also slice up the brain and see its internal structure. When the microscope was developed we could then look at the microscopic structure of the brain, and by using different staining techniques we could visualize the branching structure of axons and dendrites (the parts of neurons that connect to other neurons), we could see that there were different kinds of neurons, various layers in the cortex, and lots of pathways and nodes.

But even when we had a detailed map of the neuroanatomy of the brain down to the microscopic level, we still needed to know how it all functioned. We needed to see neurons in action. (And further, there are lots of non-neuronal cells in the brain such as astrocytes that also affect brain function.) At first we were able to infer what different parts of the brain did by examining people who had damage to one part of the brain. Damage to the left temporal lobe in most people causes language deficits, so this part of the brain must be involved in language processing. We could also do research on animals for all but the highest brain functions.

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Sep 23 2021

Will We Respect a Robot’s Authority?

The robots are coming. Of course, they are already here, mostly in the manufacturing sector. Robots designed to function in the much softer and chaotic environment of a home, however, are still in their infancy (mainly toys and vacuum cleaners). Slowly but surely, however, robots are spreading out of the factory and into places where they interact with humans. As part of this process, researchers are studying how people socially react to robots, and how robot behavior can be tweaked to optimize this interaction.

We know from prior research that people react to non-living things as if they are real people (technically, as if they have agency) if they act as if they have a mind of their own. Our brains sort the world into agents and objects, and this categorization seems to entirely depend on how something moves. Further, emotion can be conveyed with minimalistic cues. This is why cartoons work, or ventriloquist dummies.

A humanoid robot that can speak and has basic facial expressions, therefore, is way more than enough to trigger in our brains the sense that it is a person. The fact that it may be plastic, metal, and glass does not seem to matter. But still, intellectually, we know it is a robot. Let’s further assume for now we are talking about robots with narrow AI only, no general AI or self-awareness. Cognitively the robot is a computer and nothing more. We can now ask a long list of questions about how people will interact with such robots, and how to optimize their behavior for their function.

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Sep 21 2021

Virtual Phobia Treatment

Are you afraid of spiders? I mean, really afraid, to the point that you will alter your plans and your behavior in order to specifically reduce the chance of encountering one of these multi-legged creatures? Intense fears, or phobias, are fairly common, affecting from 3-15% of the population. The technical definition (from the DSM-V) of phobia contains a number of criteria, but basically it is a persistent fear or anxiety provoked by a specific object or situation that is persistent, unreasonable and debilitating. In order to be considered a disorder:

“The fear, anxiety, or avoidance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.”

The most effective treatment for phobias is exposure therapy, which gradually exposes the person suffering from a phobia to the thing or situation which provokes fear and anxiety. This allows them to slowly build up a tolerance to the exposure (desensitization), to learn that their fears are unwarranted and to reduce their anxiety. Exposure therapy works, and reviews of the research show that it is effective and superior to other treatments, such as cognitive therapy alone.

But there can be practical limitations to exposure therapy. One of which is the inability to find an initial exposure scenario that the person suffering from a phobia will accept. For example, you may be so phobic of spiders that any exposure is unacceptable, and so there is no way to begin the process of exposure therapy. For these reasons there has been a great deal of interest in using virtual/augment reality for exposure therapy for phobia. A 2019 systematic review including nine studies found that VR exposure therapy was as effective as “in vivo” exposure therapy for agoraphobia (fearing situations like crowds that trigger panic) and specific phobias, but not quite as effective for social phobia.

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Sep 14 2021

Cognitive Control and Cheating

Published by under Neuroscience

It is a fundamental truth of human behavior that people sometimes cheat. And yet, we tend to have strong moral judgements against cheating, which leads to anti-cheating social pressure. How does this all play out in the human brain?

Psychologists have tried to understand this within the standard neuroscience paradigm – that people have basic motivations mostly designed to meet fundamental needs, but we also have higher executive function that can strategically override these motivations. So the desire to cheat in order to secure some gain is countered by moral self-control, leading to an internal conflict (cognitive dissonance). We can resolve the dissonance in a number of ways. We can rationalize the morality in order to internally justify the desire to cheat, or we can suppress the desire to cheat and get a reward by feeling good about ourselves. Except experimentally most people do not fall at either end of the spectrum, but rather they cheat sometimes.

Recent research, however, has challenged this narrative, that cheating for gain is the default behavior and not cheating requires cognitive control. A new study replicates prior research showing that people differ in terms of their default behavior. Some people are mostly honest and only cheat a little, while others mostly cheat, and there is a continuum between. Perhaps even more interesting is that the research suggests that for those who at baseline tend to cheat, markers of cognitive control (using an EEG to measure brain activity) increase when they don’t cheat and behave honestly. That’s actually not the surprising part, and fits the classic narrative that people tend to cheat unless they exert self-control to be honest. However, those who are more honest at baseline show the same markers of increased cognitive control when they do cheat. They have to override their inherent instinct in the same way that baseline cheaters do. What’s happening here?

Before I discuss how to interpret all this, let me explain the research paradigm. Subjects were tasked with finding differences between two similar images. If they could find three differences, they were given a real reward. However, some of the images only had two differences, so subjects had to either accept defeat or cheat in order to win. First subjects were tested at baseline to determine their inherent tendency to cheat. Then they were encouraged to cheat with the rigged games. EEGs were used to measure theta wave activity in specific parts of the brain, which correlates with the degree of cognitive control. Subjects who cheated more at baseline showed increased theta activity when they didn’t cheat, and those who were more honest at baseline showed increased theta activity when they cheated.

Therefore, it appears more accurate to say that cognitive control allows us not to do the morally “correct” thing, but to act against our instincts, whatever they are. But why would people have such different instincts in the first place?

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Sep 02 2021

Bionic Arms

The term “bionics” was coined by Jack E. Steele in August 1958. It is a portmanteau of biologic and electronic. Martin Caidin used the word in his 1972 novel, Cyborg (which is another portmanteau of cybernetic organism). But the term really became popularized in the 1970s TV show, The Six Million Dollar Man. Of course, at the time bionic limbs seemed futuristic, perhaps something we would see in a few decades. Thirty years always feels like far enough in the future that any imagined technology should be ready by then. But here we are, almost 50 years later, and we are nowhere near the technology Steve Austin was sporting. Bionics, as depicted, was more like 100 or more years premature. This is tech more appropriate to Luke Skywalker’s hand in Star Wars, rather than some secret government project in the 1970s.

We are, however, making progress, which I have been writing about periodically here. Now a team at Cleveland Clinic has produced a robot arm tested in two subjects, and they are breaking out the term “bionic” to describe their technology. They achieve their level of functionality by combining three aspects of a brain-machine interface connecting to a robotic limb – intuitive motor control, touch sensation, and kinesthetic sensation (simulating proprioception with vibration). The kinesthetic sensation allows the user to feel the robotic limb’s movements. The authors write:

Here, we show that the neurorobotic fusion of touch, grip kinesthesia, and intuitive motor control promotes levels of behavioral performance that are stratified toward able-bodied function and away from standard-of-care prosthetic users.

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