Neurobiology and the Brain: The Microcellular Structures and Functions

Hello everyone! This is going to be a rather interesting post. As you know, the “Y” in CY CHRIST stands for youth, which means most of us here are students. In all my classes I strive to apply as much of my learning to my work and vice versa. For one of my classes I was asked to post a discussion on a type of cell in the body and a few organelles within that cell. I wanted to keep it related to my work and something I have studied a great deal of is the neurobiology of trauma -that is- how trauma affects the cognitive and physical functions of people after a traumatic experience. The amygdala plays a key part in the process as its main job is to sense danger and alert us to that danger. I wanted to go down to the cellular level of the amygdala and study how these cells and organelles play a part in the process. 

DISCLAIMER: I am not a neuroscientist, and really have no authority in this field. I wanted to post this purely as informational and I encourage you to research for yourself and comment on any information that you find.

The Pyramidal Cell

I want to look at a specific type of neuron in the amygdala called a pyramidal cell. It’s a type of multipolar neuron, which means it has multiple connections with other neurons as opposed to unipolar or bipolar (one or two other connections). The reason it’s called a pyramidal cell is that its center, also called a “Soma,” looks like a pyramid and has many dendrites or branches coming off of it as seen in figure 1.

They are the primary means of communication and excite the prefrontal cortex and corticospinal tract, preparing us to either freeze, flight, or fight in response to a dangerous situation. Pyramidal neurons also play a role in cognitive functions, for instance, it appears that the neurons can process input from the primary auditory cortex, primary somatosensory cortex, and primary visual cortex. These cells may also play a role in recognizing objects in the visual processing areas of the brain. All this information means that these cells process data about potential danger and transmit this information to the amygdala to decide what to do! Danger Will Robinson! (Am I too old to say that?)

Three Organelles Essential to Pyramidal Cells

Now let’s go down to the organelle level. We’ll discuss three major organelles that are found not only in pyramidal cells but in all neurons. The first are synaptic vesicles. These are small spherical or elliptical organelles within the cytoplasm of the neurons. They contain proteins necessary for neurotransmitters. Neurotransmitters are the chemicals that give signals to the neurons, they also have inhibitors that block those signals. Pyramidal cells, are excited or turned on by the neurotransmitter glutamate and are inhibited or blocked by gamma-Aminobutyric acid (GABA).  These vesicles have two different shapes depending on whether or not they contain neurotransmitter inhibitors or the excitatory neurotransmitter.  The former are often flat or elliptical in shape, the latter are more spherical. 

The second and third organelle I want to talk about has to do with receptors and ion channels. Now as a quick disclaimer, this area is still actively being researched and there are many hypotheses as to the exact nature of these organelles.

The Presynaptic Density is a region of the cell that has a darkly stained material where the presynaptic membrane and the synaptic vesicles are hypothesized to dock to each other. The Postsynaptic Density is also made of darkly stained material that -as is in the name- post the synapse. Even smaller complexes such as receptors, ion channels, and other signaling molecules are likely bound to this material. These organelles are important in letting neurotransmitters or inhibitors pass through them and to their ultimate destination, through the pyramidal cells and to the amygdala. 

Summary 

There is still much to be discovered in this realm especially as it relates to trauma and its effect on people. The Amygdala does do its best to help us survive in dangerous situations, and that’s thanks to the pyramidal cell that receives and sends information on the environment, and its smaller organelles like the synaptic vesicles that determine when to excite us or to relieve us; and the pre and postsynaptic density that contains the receptors and ion channels necessary to let those neurotransmitters pass through.

Thanks for reading! Please let me know if I have missed something in my research. I’ll do my best to answer any questions you have. It took a great deal of digging to find this information and I am interested in learning more.

The first link is a brief video on the Neurobiology of  Trauma.

The next are some of the places where I obtained my information. 

https://nba.uth.tmc.edu/neuroscience/m/s1/chapter08.html#plasmalemma

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4571506/

https://www.sciencedirect.com/science/article/abs/pii/S0940960202800425