AP Biology class blog for discussing current research in Biology

Tag: Nervous System

3300 Strains of Cells?

21 papers published on October 12th 2023, have revealed there is more to the brain than previously known. 3300 types of brain cells, a magnitude greater than previous reports, were discovered with the help of the Brain Atlas, a $375 million effort started in 2017. These new discoveries were made possible by new technologies that allowed scientists to probe millions of human brain cells with biopsied tissue or cadavers. This discovery is just the beginning, though, as these discoveries only sampled a small fraction of the 170 billion cells in the human brain. The process of obtaining the cells was lengthy and required several sources such as people who had recently passed away and those undergoing brain surgery.  Scientists attached glass tubes to each cell to inspect their electrical activity, injected dye to make their structure visible, then extracted the nuclei from the cells. Although this new discovery provides an astonishing amount of new data, the amount of cells discovered is only a fraction of the total number of cells within our brains so there could be up to 3300 more types of cells that we have yet to discover.

Mouse brain cells

An article published only two days after the one described above looks further into the 3300 cells types. The article identifies that the cells can be grouped into 461 clusters. In addition, new brain cells were found inside the cerebral cortex, the region of the brain responsible for memory, and language. Furthermore, an article published on the same day claims that neuron cells, responsible for transmitting stimuli, were present alongside the new cells in the samples they received. The article then identifies that from the cells obtained, half were neuronal cells and half were not.

Neurons, identified in half of the new cells, are the fundamental parts of the brain and nervous system. Our most recent topic in AP Biology is neurons and their functions. Neurons have many functions such as receiving sensory input from the external world, sending commands to the muscles, and transforming the electrical signals sent out during this process. The appearance of a neuron consists of three parts: dendrites, an axon, and a soma which can appear like a tree without leaves. Neurons are located all throughout the brain, with 10-20 billion in the cerebral cortex and 55-70 billion in the cerebellum (wikipedia) so it is not surprising that so many were identified in the new cells. Neuron cells are similar to eukaryotic cells in some ways, but not all. Like eukaryotes, they have a cell body that contains organelles. On the other hand, neurons have two branch structures, axons and dendrites, that differentiate them from a typical cell

Although the recent discovery of 3300 new types of brain cells is an astounding advancement in the ongoing research of the brain, this discovery is only a small portion of what lies within the large, independent system, that is our brain. How many cell varieties do you think are still undiscovered? I say hundreds.






Unlock the POV of Pups: How Dogs See the World Beyond Colors.

Madsen the dog, 001

Have you ever wondered how your furry friends recognize the world around them? This question was asked by a group of scientists who recently studied how canines “see” the world not only with their eyes, but also with their nose.

For a long time, the world believed that dogs could only see the world in black and white, or that dogs could only perceive color weakly, if at all. However, this myth was debunked in 1989 by ophthalmologist Jay Neitz and his colleagues, who discovered that dogs can indeed see colors, specifically blues and yellows. They cannot perceive reds and greens, similar to color-blind human.
Assorted Red and Green Apples (deuteranope view)

The reason why dogs can’t process light as well as most human is because they only have two types of color-sensing receptors, called cones, in their retinas, similar to many mammals: cats, pigs, and raccoons. This differentiates them from humans which have three cones. In addition, most dogs have 20/75 vision, meaning that they need to be 2o feet away to see as clear as a human would from 75 feet. Their world may be somewhat blurry compared to ours.

To truly understand how dogs see the world, we must look beyond their ability to process color, as highlighted by Sarah-Elizabeth Byosiere. Dogs rely on various other senses to help them “see,” or identify objects and movements around them. For example, unlike humans who have difficulty seeing in dark environments, dogs’ eyes are made to see in both daytime and nighttime. This is because of their abundance of rods, a type of photoreceptor cell in the retinas, which aids in night vision. Rods are 500-1000 times more sensitive to light than cones which allows dogs to see better in the dark. Dogs also have a unique structure in their eyes called the Tapetum Lucidum(Shown in diagram below), which acts like a mirror that reflects light back onto the retina. This enables them to see in conditions with six times less light than what human requires to see.

This is also the reason why dogs’ eyes will glow in photos in the dark, because their Tapetum Lucidum reflects the light back.

(Structure of eyes)

Mammal eye structure (tapetum lucidum)

Another significant aspect of dogs’ perception is their sense of smell, they are 10,000 to 100,000 times stronger than that of an average human. Dog’s mighty sense of smell plays a crucial role in how they perceive the world, they can even pick up odors from as far as 12 miles. Another study published recently in the Journal of Neuroscience revealed a direct connection between dogs’ olfactory bulb, which processes smell, and their occipital lobe, which processes vision. This integration of sight and smell was not observed to happen on any of other animal species.

While human are good at recognizing different colors, dogs are more into their sense of smell that humans can’t appreciate. Dogs aren’t missing out on anything; they just have their own unique way of exploring the world around them.

In AP Biology, we learned about how neurons transmit signal to the brain when we touch, hear, see, and smell. When vision and smell is received by optic nerve in eyes and olfactory sensory neurons in noses, they will pass the information of the sight and smell to the brain through neurons. Neurons transmit signals simply through a flow of ions across the axon membrane, which reverses the distribution of charges of the neuron compared to when it is at rest. This is how a neuron passes a signal to another neuron, they will repeat this process until they reach the occipital lobe and olfactory bulb in the brain where the information of the sight and smell will be processed and analyzed.

As a biology student, I have always wondered about how canines, mankind’s best friend, and how other animals see the world in their perspective. It is fascinating to find out that all animals have their unique way of sensing the world and collecting information from the area around them. Their “sensing” strategy are often different from ours’s; human primarily uses vision to receive information of the world, but our neighbors on earth could be using their sense of smell, sense of hearing, and even echoing to accomplish the same goal! Let me know in the comments below if you are also curious about how other animals recognize our world or if you are interested in this topic! Share your thoughts with me! If you want further information about this post or on this topic in general, please go to for more information and further research.

Ballerinas Got the Brains!

A 2013 research article conducted by scientists at the Imperial College of London has dived into the ballet world and researched the brains of ballerinas. Their research led to the discovery that dancers can suppress signals of dizziness using the balance organs of the inner ear. The vestibular system, found in the inner ear, consists mainly of smaller circular canals. Each canal recognizes different motions: Up and Down, Side to side, and tilting. These canals are filled with hair and liquid which move with your body to send signals to the brain using the acoustic nerve. With this information, your brain can process balance, dizziness, and vertigo. These researchers became curious about how ballet dancers can perform multiple balanced pirouettes without feelings of dizziness. And as a dancer, I would say this is because of the technique of spotting which involves rapidly moving the head to keep one’s eyes on a fixed spot.

However, this study has proved that wrong. So, with the help of 29 ballet dancers and 20 rowers, the researchers put it to the test. Their method of testing involved putting the volunteers in a dark room and spinning them on a rotating chair. They then timed how long it took for the dizziness to stop. In addition, the researchers measure eye reflexes triggered by the vestibular organs and later completed MRI scans of the patient’s brain structure. The data they collected showed that the eye reflexes and perception of spinning lasted a shorter time with the dancers than with the rowers.

From this point, doctors wondered how they could transfer this ability to their patients. After taking an in-depth look at the dancer’s brains it was concluded that the cerebral cortex and cerebellum were the most affected. The cerebral cortex is found in the largest part of the brain and is responsible for speech, judgment, thinking and reasoning, problem-solving, emotions, learning, and the senses. While the cerebellumMajor parts of the brain, a fist-sized portion found in the back of the brain, uses neurons to coordinate voluntary muscle movements and to maintain posture, balance ,and equilibrium. In the AP Biology curriculum, learning the nervous system helps in one’s understanding of transport and membranes. The nervous system sends signals across the plasma membrane of a cell to the brain. With this signal, the cerebellum and cerebral cortex can process information and signal parts of the body to move. From looking at the MRI scans, scientists discovered that the dancer’s cerebellum was smaller. Scientists believed dancers would be better off not using their vestibular system and solely relying on “highly coordinated pre-programmed movements”. Scientists believe it is not necessary for dancers to feel dizziness so, their brains adapted to suppress that feeling. As a result, the signal that goes to the cerebral cortex is reduced. So, if scientists and doctors monitor the cerebral cortex they could begin to understand how to treat patients affected by chronic dizziness.



Tired of Listening to Mom? Here’s why teens grow to explore unfamiliar voices instead of the familiar

Brain-computer interface experiment

On April 28th, 2022, Lauren Sanders, a neuroscientist and senior writer, published an article regarding the internal neurological development of kids to teens. Sanders’s primary inquiry surrounded a research article about how the development of what individuals perceive benefits them influences what voices they interact with. Specifically, Sanders’s scope of inference is based on Daniel Abrams’s study where the brain activity of a group of individuals aged seven through 16 was observed to see their responses to the voices of a mother and to unfamiliar voices too.

Abrams posed the idea that the brain activity of teens is piqued by the possibility and mystery of reward when engaging with unfamiliar voices. The biologist and anthropologist Leslie Seltzer continues this conversation by juxtaposing this idea with how kids have more increased brain activity when hearing the voice of their mother. She introduces the theory that our maturity connects to how we are less dependent on a mother figure and more dependent on our peers. Moreover, she extends this research on how powerful the voices of maternal figures have in the reduction of stress hormones.

In an age where communicating messages can be sent over text, Seltzer claims that there exists a power of voice over text where emotions and neurological signals greatly increase by hearing the authentic/emotional message in person. Further research can be conducted on the difference between voice and text, which could provide even more insight into how the increase technology use in teens could influence how teens respond to voices.

These differences in brain activities reminded me of the functions of membrane proteins. One of the significant functions of membrane proteins is signal transduction, where proteins act as receptors for hormone signals and neurotransmitters. On a more micro level, this biological lens informed me of how we humans react and respond to these voices from cell to cell.

I feel that it’s quite early to make full conclusions about causation, especially since the scope of the study is small. It’s hard to draw these connections when there are confounding variables like socioeconomic status and stability in the household, especially if these factors can simply disrupt the fluidity of communication between parental figures and children.

Stem Cells to the Rescue

Nerve damage has always been thought of to be permanent.  Now, recent studies show that stem cells are actually able to help the regrowth of nerve cells, and restore function to damaged areas.  The discovery of stem cell ability to do this has not only stunned the scientific community, but in the years to follow will have a gargantuan effect on the diagnosis’ and treatments of many nerve related diseases.

Stem cells can be found throughout the body in numerous locations: Bone marrow, blood, blood vessels, and skeletal muscles.  What make stem cells unique to other types of cells is there ability to replicate and evolve into different types of tissue.  With this ability, scientists have taken stem cells to research them, hoping that one day that will be a common treatment for nerve damage, which currently is thought to be permanent.

A study from the University of Pittsburg School of Medicine has recently tested the compatibility of stem cells to aid damaged nerve areas on mice.  The study consisted of scientists injecting human muscle-derived stem cells into surgically created right sciatic nerve defects in mice, in charge of controlling movement in the right leg.  The study found that six weeks post injection the mice that were treated with the human stem cells had recovered full nerve functionality, while the mice that were left untreated experienced limited nerve regrowth and functionality.

The process in which stem cells can be injected into a individual are as follows: Firstly, a hollow tube filled with stem cells is placed in the injured site.  This is the most common, and most studied process of how to inject stem cells.  There are alternative ways in which to do so which involve injecting the cells into hydrogel prior to inserting them into a hollow tube, but this method seems to be far more tedious and expensive, and not delivering the same results.

These findings can prove to be absolutely revolutionary to treatments for diseases such as MS and ADEM.  As of now, patients diagnosed with MS know that they will have that disease for the rest of their life.  Stem cells will now be able to be injected into the CNS to help regrow the damaged nerves.  I believe that this is one of the most game-changing discoveries in science, altering the way we look at the nervous system as something that cannot be fixed once damaged.

What is your take on the recent discoveries of usage of stem cells?  Post your thoughts, comments, or critiques in the comments.

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