Showing posts with label Executive Function. Show all posts
Showing posts with label Executive Function. Show all posts

Sunday, June 13, 2021

How To Grow a Third Arm: Neuroplasticity, Synaptic Pruning, & Myelination



Learning By Doing


It's amazing —stunning, actually — how quickly the brain can adapt. A really wild example of the brain's adaptivity is growing a third arm. You can actually do this at home [1]. To grow a third arm, you will need the following supplies: 
  1. An accomplice 
  2. A rubber hand
  3. A small brush
  4. A blanket or towel
  5. A very sharp knife or hammer
First, place your real hand and the rubber hand next to each other. Then, cover up your arm with the blanket so only the hands are visible. Then, have your accomplice use the small brush to stroke both the real and fake hand at the same time. Do this for a minute. This step is crucial because you are creating a conflict in the brain that it must eventually resolve. In the final step, have your accomplice threaten the rubber hand with the knife or hammer. If the brain successfully completes the remapping, then you will withdraw your real hand because your mind has taken ownership of the fake hand [2]!

The Adaptive Brain

The "rubber hand illusion" isn't just a fun parlor trick to play with your friends at Halloween. Neuroscientists have figured out how get people to rewire their brains so they can control a third robotic arm [3].

These stunning demonstrations show how remarkably adaptable and resilient the brain is. This adaptivity is analogous to the mechanism the mind uses after suffering a trauma. For example, if a specific region of the brain is damaged, then it has some capability to accommodate that trauma. In extreme cases, the brain will adapt by overtaking adjacent tissue so the individual can regain some of their original functionality. 

What are the specific neural mechanisms for these adaptations, and what are some real-life implications?

Adaptivity and Late Bloomers

In a previous post, we learned that executive functioning (EF) is situated in the pre-frontal cortex (i.e., part of the brain just behind the forehead). Given its centrality to higher-order thinking, it is surprising to learn how late executive functioning develops. During young adulthood, the brain undergoes two important processes: synaptic pruning and myelination

Synaptic pruning sounds horrifying, but it is a necessary process whereby unnecessary synapses (i.e., the connections between neurons) are removed. 

Myelination is the process of adding a layer of lipids (or fat) to the outside neuron. The purpose of myelin is to speed up neural transmission. It's analogous to adding insulation to an electrical wire.

By most estimates, the frontal cortex isn't fully myelinated until a person reaches 25 years of age. That might explain why teenagers and young adults don't always make the best decisions. Their brain is still developing in the most critical region for planning, organization, response suppression, and (perhaps most importantly) counterfactual thinking! 

The Classroom Connection

Understanding the timeline for neural development also has an important implication for education. Some students are late bloomers and need extra time for their frontal lobe to fully develop [4]. To give these students the time they need, there should be some flexibility in their educational timeline. Taking a "gap year," traveling abroad, or enrolling in AmeriCorp might be precisely what these students need. Not all students should be expected to rush directly from high-school to college. 

In closing, we owe our brains a great debt of gratitude. Being adaptive and flexible is what makes us who we are. And who knows...maybe someday "being who we are," might include controlling a third arm. 💪


Share and Enjoy!

Dr. Bob

Going Beyond the Information Given

[1] The illusion of owning a third arm [link].

[2] Threatening a rubber hand that you feel is yours elicits a cortical anxiety response [link].

[3] Penaloza, C. I., & Nishio, S. (2018). BMI control of a third arm for multitaskingScience Robotics3(20).

[4] Karlgaard, R. (2019). Late BloomersThe Hidden Strengths of Learning and Succeeding at Your Own Pace. Broadway Business.


Wednesday, March 24, 2021

The Mind’s CEO: Executive Function


Executive Function

Learning By Doing

Let's play a game. It's super fun...I promise! Download and print this file. Your goal is to cross out all of the lower case d's with two dots above it. Try to be as fast and accurate as possible. Don't forget to time yourself. Ready? Go! [1]

Back to the Front

Stop me if you've heard this one. The left hemisphere of your brain is responsible for logical processing; the right hemisphere is designed for creative and wholistic thinking. While there may be a tiny grain of truth to these over-generalizations, there is a much less talked about difference in brain functioning. As you go from the back of the brain to the front, thinking goes from extremely concrete to highly abstract. 

That's right! The very back of your brain is reserved for visual processing and low-level muscle control. But as you move forward, toward your forehead and eyes, thinking becomes much more complex. This is the location of higher-order thinking skills such as planning, organizing, and problem solving. This area of the brain called the pre-frontal cortex. This is where you will find executive functioning.

Executive function includes several different cognitive processes. They include, but are not limited to, working memory, response suppression, and attentional focus. 

Working Memory

Baddeley's model of working memory features three components (see Fig. 1). There are two slave systems — the visuospatial sketchpad and the articulatory loop — and a central executive. The central executive controls the operation of the slaves systems. It can store and retrieve information from each slave system, and it can also re-represent the same piece of information in different forms (e.g., translating a piece of an image into a word, or vice versa). 

In other words, the central executive must make decisions about the relevance of information and how best to represent it. It must also decide which information needs to be refreshed and maintained in working memory and which information can be safely discarded.

Figure 1. Baddeley's model of working memory.

Response Suppression

We all know how difficult it is for some people to suppress the urge to respond in certain situations. Below are several examples of response suppression, categorized by the domains in which they were found:

Popular Culture: Response suppression failure has made its way into movies (e.g., Roger Rabbit cannot contain himself when faced with the old "shave and a haircut trick") and games. In a previous post on Ironic Processing, we talked about the frustration inherit in the game of Taboo!.

Psychology: We also see examples of response suppression in the materials used in cognitive psychology. The Stroop task is a classic example because, in one variant of the task (i.e., when the color of ink and word conflict), you must suppress the urge to read the word and name the color of ink. 

Neuroscience: The frontal lobe (i.e., the seat of executive functioning), is responsible for response suppression. There is a really interesting example from neuroscience where Phineas Gage had his fontal lobe damaged. After his accident, he became something of a jerk. His behavior strongly suggested that he could not suppress his urges.

Classroom: Response suppression in the classroom is very real, and it can take on many different forms. Behaviorally, little kids (eventually) learn that they must raise their hand before blurting out the answer to the teacher's question. 

A more cognitive example can be found in the world's shortest IQ test
  1. A bat and a ball cost $1.10 in total. The bat costs $1.00 more than the ball. How much does the ball cost? _____ cents
When confronted with a question like this, you may feel the need to suppress your intuitive answer (10 cents) and apply your knowledge of algebra to determine the answer ((b+100) + b = 110). In this case, the fast answer isn't the right answer [2].

Attentional Focus 

In a previous post, we talked about the "myth of multitasking." Most people think they can do multiple things at once, but there are severe limitations. You might be able to walk, talk, and chew gum, but you won't be able to listen to a lecture, deeply process the contents, and simultaneously take notes. People are serial processors (as opposed to "parallel processors"). A useful metaphor for attention is that it is a spotlight, and it can only shine on one thing at at time. 

As serial processors, we need to make decisions about which stimuli to pay attention to. This is where executive functioning comes into play. When an alert goes off on our phone, we have to decide to pay attention to it (or not). Unfortunately, that "decision" isn't really a decision anymore. Over time, we become conditioned to immediately abandon what we were thinking about and look at our phone. In other words, we have trained our attentional system to give our phone primary status. Ideally, we would structure our learning environment so that it removes unnecessary distractions. Keeping cellphones on "Do not disturb" mode and out of view is the best way to prevent our attention from being captured.

Attentional distraction can also be internally generated. For example, if you are a minority, and you are reminded of your minority status, perhaps because of an off-hand comment or some other feature in the environment (i.e., you are the only one of your group), then those distracting thoughts can pull attention away from the task at hand. This phenomenon is called stereotype threat, and it has pernicious effects on performance [1].

The final example of attentional focus is on information within a task. Suppose you are asked to solve the following problem: 
Derek has 4 action-adventure video games and 9 board games. Desi has 3 role-playing video games and 2 lawn games. If they combine their games, how many video games do Derek and Desi have? 
Notice that this problem has some very tempting, but completely irrelevant, information. One skill that students need to learn is to ignore the distracting information as they solve the problem. Some teachers might recommend highlighting the relevant information (or crossing out the irrelevant information). The goal is to help the attentional system stay focused on the relevant bits.

The Classroom Connection

How can we structure the classroom environment to support the development of executive functioning? Here are a few recommendations:  

  1. We should strive to limit the number of distractions in the classroom. Put smartphones away and out of sight. 
  2. If the mode of instruction is primarily a lecture, then tell your students not to take notes during the lecture [2]. Instead, ask that they listen to what you are saying. After class is over, students should then be given a chance to write down everything they remember. I assume this is a controversial recommendation, so expect students to push back.
  3. Response suppression and attentional focus are both skills that can be learned. One way to develop these skills is mindfulness training, which is starting to gain some empirical support [4]. 

In summary, executive function is a critical component to higher-order thinking and reasoning. In other words, it definitely deserves the corner office! 


Share and Enjoy!

Dr. Bob

Going Beyond the Information Given

[1] This "game" is a test of executive function because you have to hold in working memory the symbol-to-match. The stimuli were created to be highly confusable; therefore, you must suppress certain responses (e.g., the "d" with only a single dot above it, or a "d" with two dots below it). I heavily borrowed the design from the "d2" test of executive function: Lyons, E. M., Simms, N., Begolli, K. N., & Richland, L. E. (2018). Stereotype threat effects on learning from a cognitively demanding mathematics lesson. Cognitive science, 42(2), 678-690.

[2] The "intuitive" versus "algebraic" answer is a good example of the distinction Daniel Kahneman makes in his book Thinking, Fast and Slow

[3] I was fortunate enough to take a course from Herbert A. Simon. He didn't let us take notes during his lectures precisely because we are serial processors. In other words, he applied the findings from cognitive science (a field he helped start!) to his own class. 

[4] Bellinger, D. B., DeCaro, M. S., & Ralston, P. A. (2015). Mindfulness, anxiety, and high-stakes mathematics performance in the laboratory and classroom. Consciousness and cognition, 37, 123-132.