AP Biology class blog for discussing current research in Biology

Tag: neurobiology

Understanding Human Brain Cells

Cells are the basis for all living things. They provide structure and carry out functions necessary for survival. Recent studies have been conducted on the brain, examining the function of the 3,000+ cells found in the human brain. They found the brain to be extremely complex and have found the following: how brains vary among people and the similarities and differences between humans and primates. 

Animal Cell

Unique Brains

Researchers looked at 100 different cells from different brain regions and found cells called astrocytes that use their genes differently based on where they are located. For example, they can regulate blood flow, but also send mitochondria to neurons. They found staggering similarities between 75 brain cells, but they also found differences. It is widely accepted that eukaryotic cells are broken into different divisions to promote productivity. All human brain cells are similar, having an endomembrane system. The staggering similarity is that all cells will consist of a nucleus, ribosomes, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles, and mitochondria. This endomembrane system allows parts of the cell to be specialized in a specific function, increasing productivity. Being that cells have different functions, however, cells’ components vary. For example, the brain immune cells, microglia, have unique genes that they use from person to person.

Human Relationship to Primates

Researchers found that cells in the frontal cortex “didn’t differ a lot between primate brains”. While similar, human brains use genes differently from primate brains. Particularly, how cells communicate. It appears that hundreds of genes carry out “human-specific” functions. It is not yet clear as to what exactly these genes carry out. 

The evolution of man- a popular exposition of the principal points of human ontogeny and phylogene (1896) (14594999469)

These new findings are significant for the biological and neurological community, for they add more evidence towards understanding the complexity of the human brain. You may be asking why this matters if there are no definitive answers? Well, we are one step closer to finding an answer. Neuroscience is relatively new. Understanding astrocytes is vital to understanding brain malfunctions. Doctors and scientists will be able to know where the issue is occurring if they understand the anatomy and functions of the brain. Finally, deciphering the similarities and differences between the human brain and primate brain contributes to strengthening Darwin’s evolutionary theory. Given the staggering similarities, the theory seems valid. Scientists noting there are human specific genes suggest why humans are in fact different and more advanced from primates. It is important to stay patient with research for cells, for even small developments are powerful. For example, the Endosymbiont Theory is a dominant theory that also began with seemly small data and breakthroughs.

I find the make up of the human brain fascinating. It’s brilliant how we all share similar brain cells so that we can all function relatively the same. It is truly extraordinary that we all have certain cells in certain spots to conduct different functions. Did you know that simply the location of a cell impacts its entire function? Additionally, the more connections we find between our brains and primate brains, the more likely evolution seems. I am a believer in evolution due to the staggering similarities in our DNA and make up. We share 98.8% of our DNA with chimpanzees! What do you think: did we evolve from apes?

Zebra Finches Help Us Understand Speech Development

It has been known for decades that humans learn by imitating the actions and overall behaviors of their parents. In terms of learning speech, it is the memorization and imitation of syllables and sounds that allow humans to develop speaking skills over time. Still, there are some uncertainties as to exactly how the brain stores the memories needed to speak and whether or not humans can interfere with or alter the process. A group of scientists worked to answer these questions.

The Study

A recent study conducted by UT Southwestern Medical Center used zebra finches to test whether or not the memories needed to replicate speaking patterns could be formed without the use of another bird to imitate the sounds from. The answer was found through optogenetics, a process in which light is used to control areas of the brain. In the experiment, Dr. Todd Roberts, a neuroscientist with UT Southwestern’s O’Donnell Brain Institute, essentially encoded memories into the zebra finches’ brains by controlling the interactions of different regions of the brain using optogenetics. In this process, light was used to activate the neurons of a desired region of the zebra finch’s brain. The duration of time the light was shown of certain neurons corresponded to the duration fo time a syllable of a song was sung by the bird. This action-reaction process was a new “memory”. The zebra finch would now use this event as a memory to try and replicate again to learn full songs.

Dr. Roberts stated, “We’re not teaching the bird everything it needs to know — just the duration of syllables in its song.”

This discovery gives pathways to understanding different speech related circuits in the brain. Just this little piece shows that it is possible for the memories we use to learn how to speak to be generated by an artificial source, and not a living mentor.

Why is this Important?

Zebra finches vocal development is very similar to that of a humans; they hear a note sung by their father, memorize it, and repeat it. The discoveries found in this study are “providing strong clues of where to look for more insight on neurodevelopmental disorders,” says Dr. Roberts. This study could provide evidence and guidance to helping those with autism, a condition that often effects language and speech development in an individual, as well as any other neurological disorder that affects the brain. Technology and research like this can help so many people struggling with speech disorders. I believe it is important to take advantage of the resources we have today and use them to help people who need it. Do you agree? Leave a comment below!

Gut Microbes and the Brain

Neuroscientists are studying the idea that intestinal microbiota might influence brain development and behavior.

Neuroscientist Knickmeyer is looking to study 30 newborns and how they have grown into inquisitive, curious one-year olds through a series of behavioral and temperament tests. She is eager to see their faecal microbiota, bacteria, viruses and other microbes that live in their guts.

Studies of animals raised in sterile, germ-free conditions showed that these microbes in the gut influence behavior and can alter brain neurochemistry and physiology. Some research has drawn links with gut bacteria and their interactions with the brain.

Escherichia coli, a species of bacteria present in the human gut

Gut Reactions

Prior to recent research, microbes and the brain have rarely been known to interact, with the exception of when pathogens penetrate the blood brain barrier. When they do, there can be intense effects. For example, the virus causing rabies elicits aggression, agitation and a fear of water. The idea that gut microbes could influence neurobiology was not ever thought of, but this is changing.

One research study showed that IBS lead to issues such as depression and anxiety. This lead scientists to wonder if psychiatric symptoms are driven by inflammation or a whacky microbiome caused by infection.

One 2011 study showed that germ-free mice were less-anxious than mice with indigenous microbes. These studies also showed that many of these behaviors are formed during a critical period during which microbes have their strongest effects. Another problem is that “germ-free” is an unnatural situation. However, it allows for researchers to learn which microbial functions are important for development of organs or cell types.

Chemical Exploration

Recent studies have found that gut microbes directly alter neurotransmitter levels, enabling their communication with neurons.

Scientists are also studying whether or not altered serotonin levels in the gut trigger a cascade of molecular events, therefore affecting brain activity.

In 2015 research showed that myelination can also be influenced by gut microbes, at least in a specific part of the brain. Germ-free mice are protected from some conditions, for example multiple sclerosis, because it is characterized by demyelination of nerve fibers. These scientists wish to use these studies to help humans who suffer from MS.

A Move to Therapy

Tracy Bale, a neuroscientist, sought to study how microbes of pregnant mothers affect their offspring. Maria Dominguez-Bello, microbiologist, wants to see if babies born through Caesarean sections end up with microbiota similar to babies born vaginally if they are swabbed on the mouth and skin with gauze taken from their mothers’ vaginas.

For Knickmeyer, the amygdala and prefrontal cortex are the brain areas that interest her the most in her studies with the newborn infants. This is because both of these areas have been affected by microbiota manipulations in rodent models. Something she is worried might affect the study is the confounding factors such as diet, home lives and environmental exposure.


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