2022 Neuroscience Year in Review

December 22nd, 2022

With 2022 coming to a close, we asked our writers to share one thing that got them excited about neuroscience this year. Here’s what they said. 

Lindsay Ejoh: Paralyzed patients use their brain signals to communicate

One exciting development in neuroscience occurred in the field of neurotechnology- where a brain implant allowed a man unable to move a single muscle to communicate with his loved ones- entirely through brain signals

The patient in question has a neurodegenerative disorder called Amyotrophic Lateral Sclerosis (ALS), otherwise known as Lou Gehrig’s disease. Due to severe degeneration of his muscles, he lost the ability to walk, sit up, and eventually even open or close his eyes. Though motionless, his brain is still able to send signals that command movement. Researchers took advantage of this by using a brain-computer interface (BCI) to translate his brain signals into communication signals. 

The patient was trained to use the device to interpret and adjust his brain activity by having the machine play a low or high tone to tell the patient whether his brain activity was high or low. Once he knew how to adjust his brain activity, the device could present him letters, allowing him to slowly spell out words and sentences. 

Others have been able to communicate with BCI devices, but these previous models relied on eye movement for communication. Though this new technology is only in use for clinical research for now, the family of patients are being taught to use it so it can be used at home to better the lives of ALS patients who are unable to communicate at all. 

You can read more about this exciting research here!

Catrina Hacker: Bats illuminate the neuroscience of navigation

Nothing gets me more excited than neuroscientists using the natural expertise of an animal to learn something new about the brain. This year, a team of researchers from UC Berkeley studied bats to learn about how the brain represents our location in space to help us navigate the world around us. Most studies have looked at the brains of mice as they move around their cage or along tracks. Like humans, they don’t always take exactly the same path to get from point A to point B. They might stop to sniff at one point or cross to the other side of the track. The team at UC Berkeley realized that it might be easier to study the brains of bats because bats have very consistent and replicable flight patterns. The trajectory of a bat’s movement is nearly identical every time the bat moves from point A to B. The researchers used this behavior to show that the bat’s brain has very stable representations of space across days, which could explain how navigational memories are retained. I loved learning about this study because it showcases just how important the natural behaviors of different animals can be in helping us understand how our brains work. I’m looking forward to seeing neuroscientists study even more natural behaviors in 2023 and beyond.

You can read more about the study in this research summary. 

Vanessa B. Sanchez: New insights into preventing Alzheimer’s Disease

Over 6 million Americans have Alzheimer’s Disease (AD), which is a neurodegenerative disorder that kills neurons that are important for memory. There are several treatment options for patients with AD that may help manage and temporarily improve memory, but there is no direct way to prevent AD from developing. This year scientists discovered a mutation (P522R) in the PLCG2 gene, which is known to be only expressed in the brain’s immune cells, microglia, that they think holds the key to  preventing AD. 

By using a gene editing tool kit, scientists generated human microglia that contained the mutation (P522R) and injected them into the brains of AD mice. The microglia carrying the mutation began to display more protective features, such as recruiting more immune cells that are typically missing in AD inside the brain. This suggests that microglia (carrying the mutation) are indeed protective because they are able to recruit more immune cells to protect against AD. These exciting findings inspire hope for the next wave of AD research in 2023. 

Want to learn more? Check out this article!

Marissa Maroni: Uncovering brain activity after death

What happens in the brain when you die? Answering a question like this stops many in their tracks however, this year a set of scientists began to tackle this enormous question. In February 2022, a study was published where researchers measured brain waves in a dying 87-year-old individual. Fascinatingly, they recorded a specific pattern of brain waves, associated with memory recall, occurring after cardiac arrest in their patient. Researchers hypothesized that this could be the first set of evidence that a human could be recalling life when close to death. This recall of life has been reported by patients with near death experiences. However, prior to this study there was no explanation for this experience. This research is incredibly exciting as it begins to unpack more functions of the brain that we don’t yet understand! 

You can read more about this exciting discovery here!

Joe Stucynski: Small animals give big insights

For me, this year in neuroscience has been all about exploring different animal models which has probably shown through in my writings. For the first half of the year I worked in a lab studying sleep and sickness in worms, during the summer I studied how disrupted circadian rhythms can affect learning and memory in fruit flies, and this past fall I studied sleep-deprived mice and recorded their brain activity to study how microglia cells affect sleep.

While these diverse experiences were rewarding in many different ways, the thing that really sticks out in my mind is how in these animals just a few neurons, or indeed a single neuron, can have a tremendous impact on behavior. For instance, C. elegans worms’ normal sleep is controlled by exactly one neuron called the ‘ALA’ neuron. Since it’s just one neuron, you would think it would be easy to study and we would know most things about it, but new discoveries are still being made.

A recent paper showed that the ALA neuron, despite promoting sleep, is actually more active when the worm is moving around and awake. The ALA neuron seems to be keeping track of how much the worm moves, to tell it how ‘tired’ it is and determine the ‘pressure’ to fall asleep. But the exact details of how this information propagates through the worm’s neural circuits remain elusive. Imagine understanding how a more complicated brain with billions of neurons works! Neuroscience is full of daunting problems we’re just beginning to tackle, but on the other hand it makes researching the brain that much more exciting!

Sophie Liebergall: Brain cells learn to play Pong

The ability to learn remains one of the most astounding and mysterious evolutionary accomplishments of our brains. But does biological learning actually require a brain at all? Apparently not… This year, a group of researchers at the University College London (UCL) in the UK reported that brain cells lying flat in a dish were able to learn to play a game of Pong! For those born after the 1970s, Pong is a table-tennis themed game in which the player controls their paddle by moving left and right across the screen. The team at UCL first grew brain cells on top of a flat electrode array. They then converted the visual signal of the location of the table tennis ball in Pong into an electrical signal that could be communicated to the brain cells. At the same time, the authors recorded the electrical activity of the cells, and converted this electrical signal into a command that moved the paddle. Over the course of only five minutes (!), the brain cells significantly improved their performance in the Pong game. Though this study doesn’t prove that brain cells in a dish are “conscious” in our usual sense of the word, it does suggest that collections of brain cells, even outside of their natural habitat in an animal, are capable of learning. These findings could help further our understanding of how the complex process of learning is happening inside our brains. And in a science-fiction-sounding twist, they may also help lay the foundation for incorporating “biological units” like brain cells into computer hardware that could far surpass the power of our silicon-based computer systems.

You can read more about this exciting work here and here!

Omer Zeliger: Naked mole rats teach us about dialects

Dialects spring up among populations, each with unique sounds and characteristics. Dialects can even change trends led by a society’s most influential members. This occurs among animals as well, particularly naked mole rat dialects. These creepy-cute critters communicate with chirps and calls. They are incredibly social, living in collectives led by a queen. Wondering if their “speech” helps organize naked mole rats’ complex social hierarchies, a team of researchers based in Berlin asked whether each naked mole rat colony has a distinct dialect of chirps. They not only found that each colony has unique chirp characteristics that its members recognize and return, but that the colony’s queen is integral to maintaining them. After losing its queen, a colony’s dialect falls into chaos until a new regent is crowned.

I loved reading this paper mostly because it gave me an excuse to show all my friends pictures of wrinkly rodents. Beyond that, it’s exciting to see a paper focusing on social vocalizations. Much research into animal communication focuses on, for example, mating calls from birds or distress calls from mouse pups. In human terms, this is like studying language by looking at catcalls and baby talk. Even though these fields have plenty to teach us, they only scratch the surface of animal communication. It’s encouraging to see groups diving down to study the rest of the iceberg.

Margaret Gardner: Super-sized dataset reveals how the brain grows over a lifetime

It’s hard to say how much of an impact this paper has had on me – it’s literally inspired my thesis project! Working with other scientists from Cambridge University, researchers here at University of Pennsylvania compiled brain MRI scans from people all over the world to create an enormous dataset, including over 100,000 individuals of all ages. With these, they were able to build growth charts of human brain development

Growth charts show the trajectory of healthy development across time. For instance, height and weight growth charts are used by doctors to see if children are in a healthy size range based on their age and sex. However, because taking an MRI of someone’s brain is harder than standing on a scale, no one’s had enough data to make growth charts of the brain before. Now we can see how the average person’s brain develops from pregnancy all the way up through age 100! This also creates a baseline that we can compare brain scans from people with mental or neurological illnesses to. 

Most of all, I think this paper is a great reminder of all the things we still have to learn about the brain. You might think that after so many decades of research, neuroscientists had already figured out exactly how the brain grows across a lifetime. This paper makes me extra excited about neuroscience and brain imaging because it clearly shows both how much remains to be discovered and how modern technology and creativity is making these discoveries possible.

Kara McGaughey: Big revisions to the brain’s little man

For me, one of the best parts of neuroscience is that new experimental and analytic techniques continue to expand our understanding, subjecting even long-standing theories to revision. This year, I had a fun, personal experience with this process of seeing things in a new light. At the end of August, I wrote a piece for PennNeuroKnow describing Penfield’s homunculus, a theory from the 1940s that details the organization of primate motor cortex. According to the homunculus (Latin for “little man”), the organization of your motor cortex matches the organization of your body. In other words, the homunculus motor cortex map has your feet connected to your legs, your legs connected to your torso, your torso connected to your arms, and so on and so forth. However, two months after my PennNeuroKnow article went up, I opened Twitter to find that a group of researchers at Washington University in St. Louis had just completely revised the theory. They found that instead of a progression from feet to face across the cortical surface, motor cortex has three distributed regions of representation: one for the feet (shown below in green), one for the hands (blue), and one for the mouth (yellow). This finding, among others in the paper, totally rearranges the brain’s “little man” put forth so long ago. To me, this underscores that the trajectory of a scientific theory is long and sometimes windy, but new technological advances help it to bend ever so slightly closer toward the truth, which I find incredibly exciting.

You can read the Twitter thread and subsequent conversation about updating the homunculus here

Barnes Jannuzi: Seeing isn’t always believing

“Seeing is believing” is a saying most of us take for granted without a second thought. But if we think about it, most of us can come up with at least one example of when our eyes have not shown us what is really there. No, I am not talking about a drug induced psychedelic hallucination; but rather mistakes or assumptions that our brains make when attempting to 

understand the world around it. But how could our brains “make a mistake”? Or more accurately, why would they not always show us exactly what is in front of us? Well to answer that, we need to understand how much goes into not only seeing the world, but also making sense of all of the visual information our eyes take in. In this article by Catrina Hacker, we learn about not one, but three types of visual illusions that expose the turning of our brain’s inner cogs. 

For me personally, reading this article was a nostalgia trip, taking me back to my psychology class in highschool where I first learned about visual illusions. I think there is something truly beautiful about learning something that goes on in our heads without us noticing. It feels like cheating at the “video game of life” and reading the manual to our minds. Being exposed to visual illusions sparked a fascination with the brain in me, and I hope that reading Catrina’s article does the same for someone else as well. 

Thank you to all of our readers and we wish you all a restful end of the year. We’ll return with more fascinating things to learn about the brain in 2023!

References

Lindsay Ejoh: Chaudhary, U, Vlachos, I, Zimmermann, JB, et al. Spelling interface using intracortical signals in a completely locked-in patient enabled via auditory neurofeedback training. Nat. Comms. 2022. doi: 10.1038/s41467-022-28859-8.

Catrina Hacker: Liberti, W. A., Schmid, T. A., Forli, A., Snyder, M. & Yartsev, M. M. A stable hippocampal code in freely flying bats. Nature 604, 98–103 (2022).

Vanessa Sanchez: Claes, C., England, W. E., Danhash, E. P., Kiani Shabestari, S., Jairaman, A., Chadarevian, J. P., … & Davtyan, H. (2022). The P522R protective variant of PLCG2 promotes the expression of antigen presentation genes by human microglia in an Alzheimer’s disease mouse model. Alzheimer’s & Dementia.

Marissa Maroni: Vicente, R., Rizzuto, M., Sarica, C., Yamamoto, K., Sadr, M., Khajuria, T., … & Zemmar, A. (2022). Enhanced interplay of neuronal coherence and coupling in the dying human brain. Frontiers in aging neuroscience, 80.

Joe Stucynski: Miyazaki, S., Kawano, T., Yanagisawa M., Hayashi, Y., Intracellular Ca2+ dynamics in the ALA neuron reflect sleep pressure and regulate sleep in Caenorhabditis elegans. iScience, 25:104452, 2022.

Sophie Liebergall: Kagan, B. J. et al. In vitro neurons learn and exhibit sentience when embodied in a simulated game-world. Neuron 110, 3952-3969.e8 (2022). 

Omer Zeliger: Barker, A. et al. Cultural transmission of vocal dialect in the naked mole-rat. Science 371, 503-507 (2021). 

Margaret Gardner: Bethlehem, R. A. I., Seidlitz, J., White, S. R., Vogel, J. W., Anderson, K. M., Adamson, C., Adler, S., Alexopoulos, G. S., Anagnostou, E., Areces-Gonzalez, A., Astle, D. E., Auyeung, B., Ayub, M., Bae, J., Ball, G., Baron-Cohen, S., Beare, R., Bedford, S. A., Benegal, V., … Alexander-Bloch, A. F. (2022). Brain charts for the human lifespan. Nature 2022 604:7906, 604(7906), 525–533. https://doi.org/10.1038/s41586-022-04554-y

Kara McGaughey: Gordon, E. M., Chauvin, R. J., Van, A. N., Rajesh, A., Nielsen, A., Newbold, D. J., Lynch, C. J., Seider, N. A., Krimmel, S. R., Scheidter, K. M., Monk, J., Miller, R. L., Metoki, A., Montez, D. F., Zheng, A., Elbau, I., Madison, T., Nishino, T., Myers, M. J., … Dosenbach, N. U. F. (2022). A mind-body interface alternates with effector-specific regions in motor cortex. bioRxiv. https://doi.org/10.1101/2022.10.26.513940.

Image credits

Cover image created by Biorender.com

Sophie Liebergall: Image by Marcin Wichary on WikiMedia Commons

Omer Zeliger: Image by TxanTxunai on Wikimedia Commons

Kara McGaughey: Image created with Biorender.com

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