Good evening all,
I read a lot of science each week. More accurately, I scan a lot of science journal Tables of Contents, and science news headlines, and I select articles to read from them. Throughout the term, I will occasionally send you links to articles, along with a short 'blog' about why I think the article is worth sharing.
The article whose link I am forwarding below describes a recent study, whose primary finding may seem, at face value, insignificant. In this study, scientists monitored multiple (several thousand) neurons in the brains of fish, which they had trained to left, or right, in response to a sensory cue. Then, analyzing the neural recordings they had obtained, they could predict (from the neural data they collected) which direction the fish would turn, up to 10 seconds before the turn.
Wow, right? They can predict whether a fish turns one way, or the other. It doesn't sound like much. But, it is a useful result, for a number of reasons.
Experiments like this are designed to assess decision-making, something that our brains have to do an incomprehensible number of times each day. Sure, we make many 'big' decisions, conscious ones, including many with life-altering consequences (like staying in our lane on the freeway). But, we make untold more smaller decisions, many unconsciously, steadily throughout the day. Think of something like typing, or writing - each letter requires a series of motor actions, in order, that have to planned and executed, against a background of many alternative movements that are possible. That's a lot of decision-making, even just to write or type a single word. How do our brains accomplish it? What can go wrong to impair decision-making? What can we do when that happens? Each of these 'big questions' must be addressed in tiny pieces, like in the study described here.
In the neuroscience research community, there are lots of different experimental models for decision-making. Larval zebrafish do not seem like an obvious choice, but they offer several specific advantages. They are small, easy to breed and house. They are relatively low on the 'scale' of vertebrate animals, such that their use raises relatively little ethical concern. Importantly here, they (1) readily learn this simply task, (2) reliably report their decision, and, (here's the big one) have brains that are small and nearly transparent. This allows researchers to monitor essentially every neuron at once, which is quite remarkable. (Remember - these are free-swimming animals, less than a cm in length, with *tiny* brains.)
Most studies of decision-making in mammals focus on the frontal cortex. Neurons there are engaged in decisional tasks, and damage to this cortex impairs decision-making (causing slower, and often faulty, performance). This new study suggests that decision-making activates neurons across the entire brain, including in areas thought to be primary reflexive, or involved in motor coordination (like the cerebellum). It's an interesting result, and one that will cause those who focus narrowly on one region or another to take a step back, and evaluate their scope of investigation.
The second primary advantage of a model system such as this is that a system of only 5,000 neurons is one that can be computer-modeled in its entirety. We may not have all of the information about how these neurons are connected, or their individual biophysical characteristics, but we definitely have the computing power to incorporate all of them into a single model. They are multiple, ambitious projects to map and model the human brain, but they remain limited both by data as well as by computing power. The more we learn about the brain, the more we realize that neurons across the brain seem to be involved in collective networks. That's a much harder nut to crack than a group of neurons in one location being solely responsible for some singular function.
So, the next time you see even the simplest of organisms behave, such as a fly taking-off or landing, recognize that its nervous system is performing functions very analogous to our own!
I will occasionally pass along articles of this type during the semester. My purpose in doing so is to help you to become more aware of current neuroscience topics, and also to help you assess how you obtain your science and health news.
Those of us working in science obtain our scientific news, quite often, directly from the original sources: the people conducting the studies and reporting the results. They publish their findings in science journals, or present them at conferences.
Most people do not obtain their science news directly, but hear news via secondary sources, such as news releases from scientific organizations, or as science news stories from the major news outlets. These secondary reports often are then carried by tertiary outlets (smaller/other reporting sources). I'd encourage you to think a little about the translation of news from source to consumer, and the reputability of the news outlets that you use.
Along the way from source to audience, science news is normally distilled (a lot) - much of the detail is excluded or simplified, and the reports often are boiled-down to singular take-home messages, which may, or may not, be good representations of the original work. When you browse the links that I will forward, or when you access science and health news on your own, I'd encourage you to delve a little bit deeper into them, to read more than just the summaries, and to follow links back to original sources when possible (like this one: https://www.cell.com/cell/fulltext/S0092-8674(19)31380-7). Some of these ultimate sources will be behind paywalls, but others will be accessible, especially if accessed via an IUP campus computer. If you ever really want to chase down one of the source articles and cannot, let me know and I can help you get to it.
Some of the science and news sources whose links I will forward allow only a handful of free articles each month; I will try to use them sparingly. I also will generally send reports only from sources (professional societies and reputable science and news outlets) that I trust.
The material that I send you as science news will not specifically be represented on our course exams, but I do hope that the material in them makes its way into our conversations.
Have a great rest of the weekend -
Good afternoon all,
Now that our second exam is completed, we will spend a bit of time discussing the nervous and endocrine systems as we start into the 3rd unit of our course. These are the two primary regulatory systems in the body, which makes their place in our homeostatic control very important. Accordingly then, when these systems are dysregulated or hijacked, the problems that arise can be very severe.
We do not have a chapter assigned for tomorrow (Friday 18 Oct), so I would like to give you some supplemental reading, instead. You can review this material on your own, so we will not have to meet in person on Friday (tomorrow).
In lecture yesterday, we outlined the cellular basis of the nervous system, and the method by which neurons communicate with each other and their targets at synapses. Synapses are points of communication between cells, but are not actual points of physical contact between cells. The communication is achieved not by direct cell-to-cell transfer of materials, but rather through neurotransmitters, chemical signals that are released from the 'signaling' cell, drift across the synapse space, and bind to receptors on the 'receiving' cell.
If you think back to early in the term about our discussions of how cells can communicate with each other, you will picture that these neurotransmitters can have effects on their target cells by binding to receptors on the cells, and causing some change: perhaps ion channels open or close, ions move in or out of the cell (or stop flowing), or some enzyme is activated that changes the metabolism of the target cell. These changes might have the effect of stimulating the target cell (causing it to perform more of its cellular function), or inhibiting it.
As I pointed out in lecture yesterday, synapses also are the place where most of our drugs (both legal and illegal) influence nervous system function. Our drugs may change the amount of neurotransmitter that is released, or cause it to stay in the synapse for a longer or shorter time. Some drugs block neurotransmitters from binding to their receptors, or artificially activate the receptors even when no neurotransmitter is present. These all are potentially very powerful effects on synaptic function, and thus brain function. If the effects of medications are targeted to specific neural systems (sensory, motor, motivation, reward, or other), they can drastically alter our behavior and our capabilities.
When we quickly reviewed some some common drugs and their effects at the end of lecture yesterday, I noted that heroin is among our most dangerous drugs, for its ability to cause very high levels of dependence (users can't bear to be without the drug) and tolerance (users need successively larger doses to feel the same effect). Heroin is one of the opioid drugs, a class of drugs long known for their ability to relieve pain and provide pleasure/euphoria. This class of drugs includes morphine, long used clinically for pain relief.
Historically, heroin was derived from natural (plant) sources, and humans have been cultivating and using opioids for thousands of years. Poppy plants have long been grown for their opium sap, which can be consumed as-is, or refined into more-potent forms. With the advent of global travel, poppies grown in Afghanistan can produce opium sap, which can be refined into heroin and trafficked for thousands of miles. This wave of heroin across the planet initiated the opioid crisis, decades ago.
More recently, pharmaceutical advances have led to the development of many other opioids: hydrocodone, oxycodone, fentanyl, and others. They are so effective at providing pain relief that they have been heavily marketed, and heavily prescribed. Black-market sourcing and illegal use of synthetic opioids now far outstrips that of heroin, as the pharmaceuticals are typically cheaper, easier to obtain, and preferred by users because they are, in many cases, more potent. Fentanyl, for example, is estimated to be 20x as potent as heroin. Other synthetic opioids may be as much as 500x as potent.
Prescription and illegal use of opioids now has reached a crisis point in our country. One cannot listen to the news without hearing of opioid uses and deaths (even here at IUP). Opioids do target the pleasure and pain centers of the brain, but they also serve as a general depressant of respiratory function. As users become dependent upon and more tolerant of these drugs, they acquire and use them in higher amounts. This puts them more and more at risk of respiratory failure: their brains simply stop signaling enough breathing. This is especially problematic when users consume illegal drugs, for their contents may not be well-regulated. Far too often, users overdose on drugs which are more concentrated, or in higher doses, than expected.
And so, for your reading on this topic, I'm offering here below a link not to a recent news story, but rather to a more comprehensive news report that was issued last Fall. It describes some of the biology and the neuroscience of opioid addiction, but also presents a variety of personal perspectives from addicted individuals. In many ways, addiction can be considered to be a disease, and the viewpoints and anecdotes describing addiction are both powerful and scary.
This article also includes links to a few other resources on the topic of opioid addiction.
But let us add to this discussion some good news: Because the action of opioids is relatively well-understood, pharmaceutical advances have made available a very effective antidote to opioid overdose. Commonly referred to by its product name (Narcan), naloxone is a substance that binds to opioid receptors, in place of the opioids themselves. But, naloxone does not activate the receptor in the same way as do the opioids; rather, it blocks the receptor from being activated by the opioids.
Naloxone is remarkably effective, and many first responders and emergency personnel now carry it. They find themselves using more frequently than they would like, but there is no doubt that it has saved thousands of lives.
Naloxone is so important in the fight against opioid abuse that the Pennsylvania Department of Health has issued a standing order that allows public citizens to obtain it, if they believe that having Narcan might help them prevent an opioid overdose. If you think that having it would benefit you or those around you, I'd encourage you to consider obtaining it. You can start at the PA Department of Health web site, especially the text pertaining to ACT 139, which described how private citizens might obtain naloxone, through a standing prescription order:
There also are opioid resources available here at IUP, through IUP's Center for Health and Well-Being:
I can help you navigate these resources, if you like.
I hope that these materials help to put our discussions of brain structure/function and synapses into some context. I'd be happy to provide more material on these topics, if anyone is interested.
Have a great weekend - see you on Monday.
Good morning all,
In recent weeks, our lab exercises have considered EEGs, sensory function, as well as muscle control. In the news this week is a report that links all of these, in a way that may prove to be revolutionary for those with spinal injuries.
Recall that from an EEG, one can evaluate the activity in underlying neural tissue. You also will remember our diverse tests of sensory systems, which were good reminders of how broad and how important our sensory capabilities are. Most recently, we discussed how action potentials in motor neurons can be used to activate skeletal muscle.
Researchers have managed to marry all of these elements in new technology that is a real-life version of something from science fiction: a robotic suit. They have used sensory receivers and brain implants to allow a paralyzed man to control this suit, enabling him to walk for the first time in years. The subject received bran implants into his motor cortex, which recorded his motor signals. Because of his spinal injury, these signals could not be relayed to his muscles through the spine. Here, the signals were routed to electronic equipment, and then to prosthetic limbs. It look a lot of practice learning how to associate his own thoughts into the motions of his prosthetics, and there is much about the device yet to be improved, but the result remains extraordinary.
We live in a world in which advances in neuroscience and advances in technology occur at a rapid pace, and their intersections are often astonishing, and fruitful.
Have a great weekend -
Good morning everyone,
In the recent science news are articles related to several of the topics we have considered recently - this is a nice confirmation that our course topics are 'up-to-date'!
Early in the term we considered the behavior of parasitic wasps, that stun prey and then oviposit eggs within them so that their larvae have a ready food supply during early growth. In the news this week is description of a different kind of parasitic wasp, one which parasitizes other wasps.
Here, the form of parasitism is less direct, in that the parasite deposits its eggs into the same plant gall that its host occupies. The parasite larvae then can attack the host, and in doing so, they accomplish a form of behavioral and physiological 'hypermanipulation'. Not only do they use the host tissues for their own nourishment, but they actually trigger a malformed version of the hosts normal escape behavior, which ensures that the host itself doesn't escape the gall but which provides the parasite an escape route.
The degree to which parasites manipulate their hosts can be extraordinary. We are used to thinking that parasites can make use of host tissues, but examples like this reveal more complicated interactions, with some parasites hijacking host behavior as well. There are plenty of examples, such as these:
All are good reminders that host behavior, as well as host tissues, can be exploited by parasites.
Even more recently, I sent you some information about humans who have developed some ability to perform echolocation. Just this week came a report on this topic, suggesting real, functional remapping of the brain's visual cortex to support this new capability:
At some level, neural plasticity is responsible for all that we can learn, but to have whole-scale re-functioning of a part of the brain from one sense to another is very impressive.
Have a good weekend -
Good morning all,
We recently considered bat echolocation as a model for sensory coevolution. During our discussions, we noted that many animals have sensory capabilities outside of the range of humans.
How about humans who can perform echolocation?
There are a small number (few dozen) people in the world who have developed some level of proficiency at echolocation for navigation. Daniel Kish is the most famous person with these abilities (but there are others):
In all of these cases, the ability came about after a loss of vision. Our human visual cortices make up a huge part of our brains, and once they are freed from visual responsibilities, it seems that they can be co-opted (at least in part) for other uses. This neural flexibility is well-known, as it is the basis for the recovery that is possible from brain trauma, including stroke. Blind persons who read Braille are known to have some expanded touch sensitivity in visual areas of the brain, and sensory re-mapping is known to occur in persons with high-levels of musical training, or in new mothers nursing infants. Still, the development of echolocation as a sensory capability is quite different, in that it adds to the human sensory repertoire, not simply expands upon an existing sense.
There are lots of interesting articles about human echolocation, including:
Next time you find yourself in a dark room, you might be tempted to give it a try! I think that I will stay close to the light switch...
Have a great weekend -
Good morning everyone,
We soon will be discussing the brain and nervous system, and our discussions will include the concept of 'body maps' in the brain. These represent areas of the brain that contain neurons that are spatially arranged to correspond to particular areas of our bodies (like our fingers and faces). We all have them, and they make some of the computations required by our brain a bit easier. Specialized training (such as the playing of a musical instrument) can modify these maps, making them (in some case) larger and more sensitive.
In the science news this week is a report about these brain maps, but in an unusual way. This news describes brain maps that represent the fine motor skills one develops as a painter, but with a catch: these are painters who use their feet, rather than their hands. In these subjects, the 'brain maps' for their feet have been come elaborated, much like what happens to the brain maps for fingers when highly trained to perform a skill like a painting.
This story reminds us of a number of important features about the brain: even in adults, much of the brain is 'plastic', or modifiable - that is the secret to our ability to learn new things. This story also demonstrates the old saying the 'nature abhors a vacuum' - if part of the brain is not being used a its normal task, in some cases that task can be shifted elsewhere, and parts of the the brain 'reassigned' (to some degree) to new responsibilities. This flexibility is also a hallmark of our brains, and is an important one, for it contributes to recovery from brain injuries, like stroke. When areas of brain tissue are damaged, in some cases nearby areas can be trained to take over those functions that are no longer being served.
So, even if you find that painting is not something you are good at (as I have), don't despair! You have plenty of brain tissue ready and waiting for your hidden talents to emerge...
Have a great weekend -
As we (hopefully? finally?) transition from winter into spring, we find that we enjoy even slightly warmer days than we have been experiencing, even if the same temperature is enjoyed less at other times of the year (for example, as autumn cools into winter). Why should a 50 °F day be perceived differently, at different times of the year?
Part of the answer has always been assumed to be psychological: we evaluate new conditions relative to what we have recently experienced, and warmer days in the spring are enjoyed relative to the recent, cooler temperature of winter. Increasingly, however, evidence is growing that suggests a physiological component, based on relatively gradual acclimation to prevailing temperatures over a longer term (weeks, months, or longer).
These data suggest that long-term physiological responses to temperature gradually shape our vasoconstriction and blood delivery to the surface (you knew there was a link to our current lecture topics!), as well as our sensitivity and tolerance to temperatures below and above our 'comfort zone'. This is part of a systemic response: our peripheral blood delivery is altered, our sensory systems modulate their responsiveness to temperature, and our minds reduce expectations of a quick change back to more moderate temperatures (which reduces disappoint when temperatures remain extreme).
So, the next time you are enjoying a bit of sunshine on a brisk Spring day, remember that the pleasure of it is not 'all in your head' - some of it is in your skin, and your arterioles, and your hypothalamus, and your skeletal muscles, ....
Happy Spring -
Good morning everyone,
In our recent chapters, we have been considering aspects of nervous system structure and function. During our discussions, we noted that the cerebral cortex of the forebrain is responsible for our "higher" functions, including emotion, reasoning, and planning. Many would argue that these are uniquely human, or at least developed to a higher degree in humans than in any other animal.
Chief among these "higher" functions is that of consciousness. Consciousness has been described as a form of "meta-awareness" (literally, being aware that we are aware). While there are many aspects of neural function that we still do not understand, the neural basis for consciousness is generally agreed to be the most challenging. In fact, consciousness is often described as "the hard problem" of neuroscience, which is a way of saying that it is so poorly understood that we do not really know even how to begin study of it, let alone explanation of it.
As our tools and our thinking are refined, however, more and more investigators are willing to study consciousness. In doing so, they often invoke aid from philosophers and psychologists, for not only is consciousness the ultimate emergent property, it cannot be isolated from itself - we are consciously trying to study consciousness, and that has significant implications for our approaches and our interpretations.
I'm passing along here a link to a recent news article describing (perhaps) a new way of thinking about consciousness, and the study of it. It describes the work of a number of the most prominent neuroscientists working today (including Giulio Tononi, Cristof Koch, and Stanislas Dehaene). This article describes some of the modern techniques used to study consciousness, and also presents some specific models for how consciousness may occur. In doing so, it also offers some specific predictions that might be tested, which will allow us to evaluate which models may, or may not, be plausible.
If you are interested in the "brain-mind" problem, as it is called, you might enjoy this article.
Hope that your Break is a good one!
Good morning all,
As I scan the science news each day, I often read articles that are interesting, and potentially useful. Less frequently do I encounter news reports that make me say 'wow!". Here is one that did.
You will recall from our sensory systems chapter that the photoreceptors in our eyes exist in several forms, and that each form is able to interact with light of some defined frequency range. Together, they give us our vision in the range of light frequencies known as "visual light". Many other organisms can detect light frequencies outside of our visual range, including infrared and ultraviolet.
This news report describes a recent advance that marries technology and neuroscience (two of my favorite topics). Here, scientists have developed molecules that act as intermediates between the light entering the eye and the light striking the photoreceptors. These molecules harvest light of one frequency, and emit it at another (the phenomenon of fluorescence). In this case, they have been designed to harvest a light frequency normally unavailable to us (and to mice), and to then emit it at a frequency to which our photoreceptors are sensitive. The effect is to allow vision under light frequencies which are not normally useful to us.
As the article notes, these experiments only have been performed in mice, to date. But, you can be sure that human applications are coming. I think that they will have to build-in some sort of kill-switch, first - a way to get rid of the molecules should they prove problematic. My guess is that they are already working on it...
Have a great rest of the weekend -
Good morning, to all of you early birds -
We all probably have trouble fitting everything into our busy schedules, and sometimes our sleep is shortchanged. Do you get enough sleep? Is one long bout of sleep better than two shorter bouts? Why do we need to sleep, anyway?
These are just a few of the many interesting questions about sleep, and scientists are tackling them, one small step at a time. One recent study (link below) suggests that, if you can't get a full 9 hrs of overnight sleep, having an early nap followed by a relatively short overnight sleep may, in fact, not be so bad.
Have a great weekend -