reading-neuro

[reading-neuro]

No paper today, I got caught up in mounting tissue slices onto slides.

Anyone who has done this understands the depths of my current frustration.

In other news, I am running low on papers-- I'm leaving town and won't be back until next Wednesday with a new paper, so send me any favorites! Don't even limit it to neuro or behavior! I will read anything.

[reading-neuro]

Just putting some thoughts down here, a little bonus post for y'all from the perspective of a current PhD student.

First of all: yes, American academia is an absolute mess, but that's not what I want to talk about.

This summer I am working full time in my lab since I only take classes during the standard fall and spring semesters. However, we don't have a ton of close deadlines and the vibe is not frantic (a rarity!) so I have been slowly moving towards a very egocentric approach to how I spend my days.

I'm really working on developing who I am as a scientist.

This blog is evidence-- I'm reading at least one paper every day, if not more. I'm learning a CRAZY amount of information. One of the best things I can do for my lab at the moment is simply to become more knowledgeable, on as many things as possible (90% of being a scientist is just synthesizing disparate ideas, as far as I can tell).

So I'm reading about bats, and hearing, and vestibular sensation, and human cognition, and at the moment an interesting review article in the Turkish Archives of Otorhinolaryngology on all the ways pilots can get their senses confused while flying.

I don't necessarily have a point here, I am just feeling grateful for the opportunity to focus on building the foundation for who I want to be when things are calm. Once life gets crazy again, I will have a head start.

[reading-neuro]

My children. My beloved followers. Lovers of brains and bats.

Today's paper is AMAZING.

A bilingual speech neuroprosthesis driven by cortical articulatory representations shared between languages is a paper from one of my favorite labs (Chang Lab at UCSF, be still my beating heart) on some incredible work they did to translate the attempted speech of a bilingual participant from JUST CORTICAL DATA. They had recording electrodes on speech-motor areas of the participant's brain, and despite the fact that he SUFFERED PARALYSIS THAT PREVENTED HIM FROM SPEAKING, they made massive strides in being able to decode the words he was attempting to say.

The parameters of the experiment prevented naturalistic speech-- he had to try to say specific words in a stilted, time-dependent way, rather than just saying what he wanted-- but they were able to accomplish a decoding accuracy rate of around 87% for almost 200 words in English and Spanish.

87% of the time, their decoding methods could determine what language and word the participant was trying to say, just from electrical activity in his brain.

There's still a long way to go to make this better. 200 words isn't a lot, and there were some hefty limitations on his ability to communicate what he wanted to communicate. Not to mention this is just one guy. But to be quite clear? This is science fiction, and this is the reason we need to support scientists, so people like Pancho can speak again after life-altering health tragedies.

Silva, A.B., Liu, J.R., Metzger, S.L., Bhaya-Grossman, I., Dougherty, M.E., Seaton, M.P., Littlejohn, K.T., Tu-Chan, A., Ganguly, K., Moses, D.A., & Chang, E.F. (2024). A bilingual speech neuroprosthesis driven by cortical articulatory representations shared between languages. Nature Biomedical Engineering, 8:977-991.

[reading-neuro]

Got arm hair? So do bats.

Except for the bats in Anatomical distribution and flight control function of wing sensory hairs in Seba's short-tailed bat, in which the authors used Nair to remove sensory hairs from the underside of bat wings to see how it affected bat flight.

Interestingly, some wing folding measurements were different after hair removal, suggesting that the airflow input to these hairs during flight is really important for informing the body on how to position the wings. This meant that the bats were flying with less-than-ideal wing orientation and had to increase the rate of their wing beats to stay on track. This means (probably) more muscle use, more calories burned, and more food required to fly the same distance.

This is a cool example of how the absence something innocuous, like hairs on a wing, can have huge effects on a whole system.

Be grateful for your body today!

Quinn, B.L., Bajic, J.L., Romo, S.J., Wu, A., Bortoni, A., Breuer, K., & Swartz, S.M. (2025). Anatomical distribution and flight control function of wing sensory hairs in Seba's short-tailed bat. The Anatomical Record 2025: 1-17.

DOI: 10.1002/ar.25679

[reading-neuro]

Another week, another five papers (unless I get lazy). Today's? Hippocampal place cells in echolocating bats!

Honestly this paper is a little bit boring to me, but it covers a cool topic: place cells in the hippocampus. These are cells that respond when an animal is in a specific location, which we study to understand both navigation and memory. This study specifically found that the place cells adapted (by responding to a broader range of stimuli) very quickly during recordings, more quickly than had been recorded before.

This paper is from 2011 so I'm sure plenty of work has been done on the topic since. One of my lecturers this past semester studies the hippocampus in rats so he was very emphatic about the complexity of place cells.

Thanks for appreciating brains with me today!

Ulanovsky, N., & Moss, C. (2011). Dynamics of Hippocampal Spatial Representation in Echolocating Bats. Hippocampus 21:150-161.

DOI 10.1002/hipo.20731

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Exciting news! Today we're talking about neural oscillations! (everyone ooh and ahh please). This review article, Neural oscillations are a start toward understanding brain activity rather than the end, is addressing some common misunderstandings and over-interpretations of neural oscillations.

What are neural oscillations? Think of things like pacemaker cells in the heart, or slow wave sleep: they're waves of activity that occur all over the brain without outside input. They just Happen, and our brain uses them to time events, keep track of changes in information, pace communication, etc. etc.

One of their points that I hadn't really thought about was how oscillators don't necessarily have to oscillate all the time-- they can respond to outside stimulation and oscillate to its rhythm, but then return to their own rhythm and slow down to nothing once the stimulus is gone.

A more important point I want to make here is about the value of reading papers you don't entirely understand. I've heard of neural oscillations, but most of this paper was completely new to me, and I can't pretend that I've understood it all first try.

What reading unfamiliar papers grants you isn't immediate knowledge, but the assurance that next time you encounter the topic, you'll understand it a little bit faster.

One day I might need to know about neural oscillations. The process of building that foundation began today.

Cheers!

Doelling, K.B., & Assaneo, M.F. (2021). Neural oscillations are a start toward understanding brain activity rather than the end. PLoS Biology 19(5): e3001234.

https://doi.org/10.1371/journal.pbio.3001234

[reading-neuro]

WOOOHOOOOOO FOLKS WE'RE GOING TO SPACE!!

unfortunately, we will probably get gravity sickness while we're there. :( major bummer.

Today's paper, Understanding vestibular‑related physiological functions could provide clues on adapting to a new gravitational environment, is all about SPACE and ASTRONAUTS and HOW OUR VESTIBULAR SYSTEM GETS MESSED UP WHEN GRAVITY IS WEIRD.

It's a review, so it covers a bunch of relevant research (pub. 2020), including the vestibular system's involvement in maintaining blood pressure during changes in gravity, how changes in gravity make you cold or nauseous, and how light/heavy gravity affects your muscles!

This is exactly the kind of wacky neuroscience that I LOVE. We invented a bunch of tech to change our perception of gravity, and then it makes us sick, so now we have to find ways to fix the problems we created. Such is life.

Morita, H., Kaji, H., Ueta, Y., & Abe, C. (2020). Understanding vestibular‑related physiological functions could provide clues on adapting to a new gravitational environment. J. Physiol Sci 70:17.

[reading-neuro]

Hey gang!

Today's paper is actually a letter to the editors, meaning it is short, sweet, and not actually an experiment.

It's about the idea of vestibular sensation (balance) and lateralization (things like handedness, and which side of your brain does what). The authors do a lot of vestibular sensation research, and they propose in this letter that vestibular sensation and lateralized functions like handedness develop separately, but interact with each other.

Here's the idea: the right side of your body is controlled by the left side of your brain, while the left side of your body is controlled by the right side of your brain. HOWEVER: in right-handed people, the RIGHT side of their brain is more dominant in vestibular sensation than the left-- and vice versa for left-handed people.

So these things that are both lateralized AND both involved in things like movement and spatial orientation are opposite of each other. Why? The authors think that vestibular sensation may play a role in shaping handedness, since you develop your sense of balance before you pick a dominant hand. Crazy!

This one is absolutely worth a read, I would say.

Ciao!

(P.S.: anybody who says "your right brain is creative" or "your left brain is calculated" or whatever else is lying to you, very few things in your brain are actually lateralized. The vast majority of stuff you do uses both hemispheres)

Brandt, T., & Dieterich, M. (2014). Does the vestibular system determine the lateralization of brain functions? Journal of Neurology, 262: 214-215.

DOI 10.1007/s00415-014-7548-8

[reading-neuro]

GOOD MORNING!

Today's paper is an old one (for neuro, at least) hailing from 1979. The authors explored the visual system in the brains of echolocating and non-echolocating bats-- if you didn't know that some bats don't echolocate, now you do.

They tried a couple different methods, including removing one eye and looking for the destruction of downstream neurons and injecting the eye with an early form of anterograde tracers (psst: these are just chemicals that travel down neurons the same way information does, depositing chemical along the way, so you can see what neurons are connected).

They found that, generally, the echolocating bats had a "less developed" visual processing pathway. Some areas were smaller, some seemed less connected to the eye, and some didn't have the cellular complexity of the same areas in non-echolocating bats. This all makes sense: a bat that navigates more with sound doesn't need to process visual information as thoroughly. Better to leave more of the brain for hearing.

Just for fun, here is one of the echolocating bats (Myotis lucifugus, or little brown bat, photo from Bat Conservation International):

And here is one of the non-echolocating bats (in the paper it is called Pteropus giganteus, but the modern nomenclature is Pteropus medius; regardless, it's an Indian flying fox and I got this photo from Wikipedia):

Thanks for appreciating bats with me today!

Cotter, J.R., & Pentney, R.J.P. (1979). Retinofugal projections of nonecholocating (Pteropus giganteus) and echolocating (Myotis lucifugus) bats. J. Comp. Neuro. 184: 381-400.

[reading-neuro]

It's Monday, friends! Happy pride!

This paper is by the same lab as Friday's, but published two years later. They're still looking at the auditory cortex (AC) in the Mexican free-tailed bat, but this time they're comparing it to an area in the frontal cortex called the frontal auditory field (FAF). To oversimplify a bit, we tend to characterize the frontal cortex as doing "higher order" cognition tasks-- not just hearing things, but assigning meaning to those sounds. It's involved in decision making, goal-oriented behavior, communication, and other complicated stuff.

The researchers recorded from single neurons in both areas (hundreds of neurons total) and found that the FAF neurons weren't selective towards frequencies or types of frequency modulation-- they do NOT care about the baseline traits of the sound. AC neurons are selective for these traits.

However, when it comes to recordings of actual bats talking to each other, the FAF gets WAY more selective: neurons will respond to (for example) calls 2, 3, and 5, but NOT 1, 4, 6, 7, 8, or 9.

They had some other results looking at neurons' spectrotemporal receptive fields and extrapolation from STRF responses to predict later responses, but these get very confusing so I recommend you go straight to the literature.

TL;DR: it appears that the frontal cortex of bats has an area that is super selective for particular communication calls, but NOT because of certain sound traits. How is it getting this sound information? Why does it end up encoding behaviorally significant details instead of sound characteristics? Stay tuned to (maybe) find out!

Thanks, as always, for joining me today. :)

Macias, S., Bakshi, K., Troyer, T., & Smotherman, M. (2022). The prefrontal cortex of the Mexican free-tailed bat is more selective to communication calls than primary auditory cortex. Journal of Neurophysiology, 128: 634-648.

doi:10.1152/jn.00436.2021

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This is so embarrassing. I literally forgot the citation.

Macias, S., Bakshi, K., & Smotherman, M. (2020). Functional organization of the primary auditory cortex of the free-tailed bat Tadarida brasiliensis. Journal of Comparative Physiology A, 2020(206): 429-440.

https://doi.org/10.1007/s00359-020-01406-w

Hey gang! Today's paper is a fairly straightforward one (finally).

It looks at the organization of neurons in the auditory cortex (AC) of the Mexican free-tailed bat. This is the "highest" auditory processing region-- meaning sounds have been very thoroughly processed by earlier brain regions-- and it (theoretically) does the most complicated work as a result.

They found that, similar to a lot of animals, these bats had tonotopic organization in their AC. This means that there is a gradient of neural responses across the entire region, with neurons towards the back of the head responding most to low-pitched sounds and neurons towards the nose responding most to high-pitched sounds. They also found that a very important kind of cell-- echo-delay cells-- are interspersed throughout the whole region. These neurons respond specifically to certain delay times between a vocalization and an echo, obviously really important for gauging distance during echolocation. So one neuron might "prefer" echoes that happen 4 milliseconds after the initial sound, while another might "prefer" a 10 millisecond delay.

Neat!

Thanks for tagging along, and I'll see you either tomorrow or next week.

:)

[reading-neuro]

lets modulate epigenetic stress with mama

[reading-neuro]

Hey gang! Today's paper is a fairly straightforward one (finally).

It looks at the organization of neurons in the auditory cortex (AC) of the Mexican free-tailed bat. This is the "highest" auditory processing region-- meaning sounds have been very thoroughly processed by earlier brain regions-- and it (theoretically) does the most complicated work as a result.

They found that, similar to a lot of animals, these bats had tonotopic organization in their AC. This means that there is a gradient of neural responses across the entire region, with neurons towards the back of the head responding most to low-pitched sounds and neurons towards the nose responding most to high-pitched sounds. They also found that a very important kind of cell-- echo-delay cells-- are interspersed throughout the whole region. These neurons respond specifically to certain delay times between a vocalization and an echo, obviously really important for gauging distance during echolocation. So one neuron might "prefer" echoes that happen 4 milliseconds after the initial sound, while another might "prefer" a 10 millisecond delay.

Neat!

Thanks for tagging along, and I'll see you either tomorrow or next week.

:)

[reading-neuro]

We're gonna get philosophical today! Mainly because I don't consider myself knowledgeable enough about this paper to speak with any authority.

This paper used fMRI (hey, we talked about that!) to search for Default Mode-Like Networks in bats. The default mode network (DMN) in humans is a sort of background hum in the brain, connections between brain areas that just keep chugging even when nothing particular is happening. Since bats are not humans, they only get a default mode-like network (DMLN). How anthrocentric of us.

The DMN has been associated with stuff like social behavior, internal analysis, predictions of the future, and a bunch of other stuff. Again, I am not super knowledgeable here, so sound off in the notes if you know something I don't. Point is: the DMN seems awfully... human.

So this raises the age-old question of: what's the point of using animals?

When can we use animal models to assume things about human brains? What do we actually learn from doing a brain scan of bats? (I personally just think it's neat, but that doesn't convince many people.)

It's questions like these that you really need to ask, both as a researcher and as a critical consumer of research. In this paper, using bats makes sense because they are highly social, communicative creatures, just like humans. But that doesn't mean a bat is a human, so it's important to avoid over-interpreting. A bat DMLN is almost certainly different than a human DMN (this paper found some heavy auditory system involvement, which is not as prevalent in human studies). This neither negates nor exalts the data we can gather-- it's just an essential step in interpretation said data to formulate future ideas.

Thanks, as always, for tagging along with me!

Washington, S.D., Shattuck, K., Steckel, J., Peremans, H., Jonckers, E., Hinz, R., Venneman, T., Van den Berg, M., Van Ruijssevelt, L., Verellen, T., Pritchett, D.L., Scholliers, J., Liang, S., Wang, P.C., Verhoye, M., Esser, K.H., Van der Linden, A., & Keliris, G.A. (2024). Auditory cortical regions show resting-state functional connectivity with the default mode-like network in echolocating bats. PNAS 121(27): e2306029121.

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Today's paper is very focused on the anatomy of vestibulosensation, aka your sense of balance. Ever heard of inner ear problems causing balance issues? That's because your vestibular equipment is in the inner ear, right by the cochlea!

To simplify, we're going to focus on the semicircular canals. These are three little loops in your inner ear, each designed to sense one type of rotation: forward rotation (like doing a front flip), sideways rotation (like doing a cartwheel), and horizontal rotation (like a ballerina spin). Those are not scientific terms, but they work for me!

This paper is specifically looking at the size of these canals in a bunch of species of bats-- bats are very interesting since they are the only flying mammals. If you think about it, staying balanced and oriented while flying is QUITE the task. So these authors looked for any differences in semicircular canal size, relative to body size and cochlea size, between various bats and other mammals.

Firstly, they found that there weren't any differences in these size ratios in bats vs. non-flying mammals. Bummer! And also surprising.

Secondly, they found that semicircular canals were generally smaller in bats that echolocate. This is an example of a fun evolutionary balancing act-- they need big cochleae to echolocate properly, and big semicircular canals to balance during flight, but their heads can only be so big! It appears that bats solve this problem by making their semicircular canals smaller to allow a larger cochlea. Cost-benefit analysis at its finest.

However, there are also internal changes that can be made to improve semicircular canal efficiency when they're forced to be small. One possibility is making the empty space inside the canals bigger compared to the thickness of the walls.

At the end of the paper, they list a whole bunch of outstanding questions. So as of 2013 there was PLENTY more work to be done.

Enjoy!

Davies, K.T.J., Bates, P.J.J., Maryanto, I., Cotton, J.A., & Rossiter, S.J. (2013). The evolution of bat vestibular systems in the face of potential antagonistic selection pressures for flight and echolocation. PLoS ONE 8(4): e61998.

doi:10.1371/journal.pone.0061998

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[reading-neuro]

Good morning! I'll be so honest: if you've never read a neuroscience paper before, do NOT start with this one.

We have an exciting paper today for two reasons: firstly, it's a review article rather than an experimental paper-- this means that we'll get to synthesize a bunch of information from a bunch of different papers rather than deep dive into a single procedure. Secondly, it's all about ~inhibition~, aka one of my absolute favorite traits of the nervous system!

It's also specifically looking at auditory processing in Mexican freetail bats, which is exactly what I study, so it's of particular interest to me.

Crash course on inhibition: neurons communicate with each other by firing little sparks of electricity, which prompt the release of particular chemicals, which latch on to the next neuron and tell it what to do. Some chemicals tell the next neuron to fire its own electric signal (excitatory signaling) and some chemicals tell the next neuron NOT to fire (inhibitory signaling).

Each neuron gets TONS of these inputs, some excitatory, some inhibitory, which means the chemicals duke it out to determine what the neuron should do. More excitatory inputs? Fire! More inhibitory inputs? Hold off.

This paper is specifically interested in a subset of neurons in the inferior colliculus, a brain region that takes in a bunch of information from other auditory processing regions to sort of synthesize the auditory information together. In multiple stops along the pathway, there are cells called excitatory-inhibitory (EI) cells. These cells very specifically receive excitatory input from one ear and inhibitory input from the other. Their entire job is to decide WHICH SIDE IS MORE POWERFUL-- meaning which side received the LOUDEST sound. These cells help you figure out where a sound is coming from, since the closer ear will experience the loudest volume.

The question being asked here is whether the inferior colliculus (IC) creates its own EI cells with inputs from either side OR it simply "reports" the results from EI cells earlier in the pathway. Is it doing its own work or copying its classmates?

As with all neuroscience, the answer appears to be "both". The major finding of this review was that the IC receives direct input from the lateral superior olive (LSO), which is an earlier stop in the pathway that produces its own EI cells. However, the IC also receives inhibitory input from the dorsal nucleus of the lateral lemniscus (DNLL), which modulates how the IC produces its EI cells. It's not directly copying from the LSO or the DNLL, but combining their information to produce something new.

TL;DR: As sound information gets processed, different types of information from different areas converge onto the inferior colliculus to help localize the source of the sound.

Pollak, G.D., Burger, R.M., Park, T.J., Klug, A., & Bauer, E.E. (2001). Roles of inhibition for transforming binaural properties in the brainstem auditory system. Hearing Research 168(2002): 60-78.

doi: