Wednesday, April 27, 2016

Introduction to Psychobiology - Part 6 (A Neurotransmitter known as Acetylcholine)

For more information about psychobiology, please check out "Physiology of Behavior," by Neil Carson

In this post we will cover a neurotransmitter known as Acetylcholine (ACh)

Acetylcholine (ACh)

This is thought to be the first discovered neurotransmitter by Otto Loewi (1).  To the right a drawing of a rat's brain and its acetylcholine pathway can be seen. ACh can be found in the peripheral nervous system(PNS) and the central nervous system (CNS). In the PNS it is involved with neuromuscular junction (2). This is where an axon reaches a muscle (3). Here the ACh causes EPSPs. This is excitatory postsynaptic potential and it refers to the action that increases the probability of an action potential occuring. On the other hand, IPSPs inhibit postsynaptic potentials (4). In the CNS, ACh in the basal forebrain is involved in perceptual learning and memory. In the Medial Septum, specifically the Hippocampus, ACH is also involved in learning and memory. In the Dorsolateral Pons, it can be found when individuals are passing through their REM sleep (Rapid eye movement). Finally, in the Putamen, Nucleus Accumbens, and the Caudate Nucleus Acetylcholine is involved in motor functions.

Biosynthesis of ACh

We will now look at the synthesis of acetylcholine (synthesis is the construction of a complex chemical (5)). As you can see the synthesis starts with two substances: Acetyl coenzyme A (acetyl-CoA) and Choline. Then, Choline acetyltransferase (ChAT), which is an enzyme (remember that enzymes are catalysts that either help break or unite two substances) transfers the acetate ion to Choline, thus, ending up with acetylcholine (6).

Two Subtypes of Receptors

Both of the subtypes are found in the CNS. They are nicotinic and muscarinic. The former is ionotropic, which is a receptor that is linked to an ion channels (7), is only found on muscle fibers (8). The latter is metabotropic, which obtained this name because the "movement of ions through a channel depends on one or more metabolic steps" (7).

Six Cholinergic Drugs

  1. Black Widow Spider Venom: This venom triggers the release of acetylcholine.
  2. Hemicholinium: This prevents the uptake of choline
  3. Atropine: This is a direct muscarinic antagonist. It produces dilated eyes.
  4. Curare: This comes from a plant and it prevents muscle contraction. It is a nicotinic antagonist that is direct.
  5. Neostigmine: This is an indirect agonist that blocks AChe
  6. Botulinum Toxin: Also known as Botox, it prevents release the release  of acetylcholine (8).








8. "Physiology of Behavior," by Neil Carson.

Introduction to Psychobiology - Part 5 (Drug Effects)

For more information about psychobiology, please check out: "Physiology of Behavior," by Neil Carlson

We mentioned before that drug effects are the biological and behavioral outcomes produced by introducing drugs into the body. Now we will introduce a concept known as drug-response curve that will connect to past material. This is refers to a graph that displays up to which point there is an the maximum effect obtained (1). In the picture on the right we can observe that the blue line represents the desired effect, in this case the analgesic effect, of morphine. Meanwhile, the red line describes when the dose of a drug produces a negative outcome, in this case the depressive effect. To measure when a drug is safe, we utilize (there are other methods to measure safety) the therapeutic index. This is the ratio between two numbers. The first one is the amount of a dose needed in order for 50% of a sample to obtain the desired effect of a drug, the second number is obtained by calculating the dose needed to cause 50% of a sample to die. The lower the ratio, the more dangerous it is to make a mistake by prescribing a drug (2).

There are two reasons why the effects of drugs vary:
  1. Each drug has different sites of action
  2. The affinity, which is the readiness by which two molecules attach, of a drug.

Binding Sites for Drugs

There are two types of binding sites. Direct and Indirect. In the former, the binding site is competitive. This means that neurotransmitters and drugs compete for the same binding site. In the latter, neurotransmitters and drugs have a separate one.

If you looked at the pictured above, you might have noticed that there are also two extra categories: agonist and an antagonist. Antagonists help inhibit the effects of the natural ligand and an agonist facilitates the effect of a neurotransmitter (3).

Interesting Fact: There are two possible outcomes for repeated use of drugs. Tolerance, which means that the effectiveness of a drugs diminishes, or sensitization, which means that the effectiveness increases.

Turnover Model

There are several ways a drug can effect neural activity, we will only cover seven (2).

  1. Synthesis: A drug can inactivate the synthesis of a neurotransmitter
  2. Storage: A drug can prevent the storage of a neurotransmitter (NT) in vesicles.
  3. Release: A drug can stimulate the release of a NT
  4. Receptor Activation: A drug can help stimulate receptors. There are two: postsynaptic and presynaptic. We will cover the latter later.
  5. Enzymatic Deactivation: A drug can help the enzymes get rid of a NT
  6. Reuptake: A drug can inhibit reuptake.
Like promised let us cover presynaptic heteroreceptors. This are usually found in axoaxonic synapses. The second axon is sensitive to the NTs of the first one. Thus, if there is presynaptic inhibition the calcium channels will close and there will be less or none NTs released from the second axon. If the opposite happens, presynaptic facilitation, the calcium channels will open, thus, facilitating NTs release. Remember that calcium is required for exocytosis. This is when a vesicle becomes part of the membrane (4).



2. "Physiology of Behavior," by Neil Carson



The Five Lectures of Freud

Sigmund Freud and his Clark Lectures

            Sigmund Freud was a neurologist and the founder of psychoanalysis (Jay, 2016). In 1909, he visited the United States in order to deliver five lectures about psychoanalysis as requested by psychologist G. Stanley Hall (Encyclopædia Britannica, 2016c). The University was celebrating its twentieth anniversary by conducting a series of lectures where prominent figures spoke about their field (Burnham, 2012). The purpose of this essay is to explore each of Freud’s lectures in detail. Before describing the lectures, it is important to understand how Freud mapped the mind. He divided it into three parts twice. The first time he categorized it into the conscious, preconscious, and unconscious (Freud, 1938).

The conscious layer contains everything that an individual is aware of, such as immediate physical experience. The preconscious contains what we are not aware of, but can bring forth to the conscious. This includes memories such as what an individual ate for lunch the day before. However, it is not limited to memories only, it also could also contain immediate physical experience that is not in the conscious such as background noise or proprioception.  The last division is the unconscious.  This encompasses elements that we are not aware of and are being repressed, which is an essential concept in psychoanalysis that will later be described. This material will not come forward to the conscious unless with the help of analysis.

The second time he organized the mind, he divided it into the id, the ego, and the superego (Rana, 1997). The superego is the part of the mind that is the last to develop and is constantly reminding the ego of rules and morals; they could be social, political, religious, etc. The id, which is innate, is the most important component in psychoanalysis. It is constantly looking for pleasure. The next division is the ego. This plays the role of moderator between the rules of the superego and the desires of the id. Moreover, the superego is both conscious and unconscious, as well as the ego. However, the Id is the only part of the strata that is solely unconscious.

            In the first lecture, Freud describes how hysteria was one of the foundations of psychoanalysis. He talks about one of his patients when he was working with Dr. Josef Breuer (Gray, n. d.). The patient was a twenty-year-old woman who was experiencing physical symptoms such paralysis, loss of sensation, trouble with her vision and speech, and for several weeks she could not drink water, this is known as hydrophobia. Another symptom was a condition called absence, where she seemed to disconnect from reality and concentrated on a special thought. When she was in this condition, she usually muttered certain words. Dr. Breuer wrote down the words and tried to use them as a starting point in order to induce hypnosis. When the patient was hypnotized, she could talk about what she was thinking during her absences, which were usually fantasies or memories. After she explored her fantasies while being under hypnosis, the physical symptoms of hysteria disappeared. She called this method of treatment the talking cure. Her picture can be found to the right side of this paragraph.

            An example of how one of her trains of thought connected to her symptoms is in the following story. During one summer, the patient visited a friend who kept a dog as their pet. This dog would drink from the glass of water of her friend, and her friend would later drink from it too. The patient explained that she had a negative opinion of her friend (she never used the word friend, but rather lady-companion), but this event was what disgusted her the most. When the patient ended telling this story, she was able to drink water once again, which meant that her symptom of hydrophobia had disappeared.

This connection between memories and physical symptoms was present for every characteristic of hysteria in the current patient and the other ones that were treated by Freud. He concluded from this that “hysterical patients suffer from reminiscences” (Freud, 1909). In other words, the symptoms are expressions of memories. The next thing to explore is what kind of memories create the basis for hysteria. For Freud it was events that consisted of suppression or repression, the former is a conscious and the latter is an unconscious process. In the example mentioned above, the patient suppresses her feelings of disgust. Another important characteristic for Freud is the evidence of conscious and unconscious states of the patient. When she was not absent she did not remember the memories that were later connected to her symptoms. And yet all of this information was already known by the patient; thus, Freud asserted that the desire of the expressions and the memories were in the unconscious and with the help of this new type of treatment it was brought to the conscious. Therefore, relieving the patient of its hysteria. A photograph of Dr. Breuer can be found to the left.

            In the second lecture, Freud explained how he discarded hypnosis, which was a central component for the process of relieving hysterical symptoms, because not all of the patients could undergo a hypnotic state. Keeping in mind that the catharsis, which is the release of an emotion, was what really helped hysteric patients, Freud tried to replicate this with individuals in their normal state. He based this direction on a demonstration by Bernheim in 1889. This French physician and neurologist showed that people who had been put into a hypnotic state of somnambulism reported to not remember what happened when they were in that state. However, when Bernheim insisted that they did, the events became conscious. Freud tried to parallel these two events, the demonstration of Bernheim and his practice by saying that the repressed memories that occurred during a state of absence would be recovered if individuals were pressed for information. The technique that he used for people in their normal state consisted of suggestion. When a patient reported that they did not remember something, Freud said that the memory would become accessible the instant when he touched their foreheads. He quickly abandoned this because he asserted that it was exhausting and consumed a lot of time.

            However, he did not stop using suggestions to allow catharsis until he found evidence that the patients indeed remembered the repressed memories or fantasies. It is important to explain that he was very careful to not use leading questions or influence the answers of his patients. Thanks to these findings he started to develop a theory that explained the origin of hysteria. Freud argued that there was a force, which he named resistance, that prevented the expression of desires and thus created this pathological condition. He explained that one process of resistance was repression.

            The cause of repression was a result of the dynamics of the mind. He describes this process by saying that the Id was a wish, a desire that will bring pleasure. Nevertheless, because it is incompatible with the rules of the superego, the ego represses it into the unconscious. Thus, the desire of a certain expression is achieved without breaking the subject’s ethical standards.

            Another example of the interactions between these parts of the mind is seen by another patient of Freud. This female patient felt attracted to the husband of his sister. When the patient’s sister died, she thought now he can marry me. The Id’s wish is to be with her brother-in-law. However, that thought becomes repressed by the ego, because the superego thinks that the statement is not appropriate. When the patient was in Freud’s practice, she reported that she did not remember this event, but after she told him this story (the memory was no longer repressed) her hysterical symptoms disappeared.

An important characteristic of Freud’s model of the mind is that each component is not independent of the other, every part is in constant interaction and that many mental aspects are the outcome of the struggle between the id and the superego chosen by the ego. Another important feature is the component that even though a wish has been repressed, it has by no means disappeared. It now exists in the unconscious, where it is trying to escape into the conscious in order to find expression. By talking about it in a psychoanalytic setting, it becomes conscious without breaking the rules of the superego. To summarize the first two chapters, memories and fantasies are connected to hysteric symptoms and the dynamic between the parts of the mind are responsible for repressing or expressing desires.

In the third lecture, Freud kept discussing the topic of repression. He explained that when he suggested to patients that they did remember a memory that was linked with their hysterical symptoms, the patients talked about things, such as memories or ideas, that were not related, at least in an obvious way, to their symptoms. Nevertheless, he thought that these set of ideas were connected to the source of hysteria, but the connection was not explicit because they were being repressed. Freud made the remark that his colleague, Dr. Carl Jung, later supported this concept with research. In other words, ideas or thoughts are connected by means of associations and the more resistance presented by the subject, the more the first set of thoughts would be distorted.

It has already been stated that hysterical symptoms were a form of expression of what the Id desired. The initial thoughts mentioned by patients were also, according to Freud, symptoms because they expressed in a distorted way what the Id craved.

These conscious substitutes of what is repressed are not only seen in patients with hysteria, but also in the everyday life of every human being. Freud described several types of ways where this process can be seen. One of them is by telling jokes. In his third lecture, Freud told the following joke: “Two not particularly scrupulous business men had succeeded, by dint of a series of highly risky enterprises, in amassing a large fortune, and they were now making efforts to push their way into good society. One method, which struck them as a likely one, was to have their portraits painted by the most celebrated and highly-paid artist in the city, whose pictures had an immense reputation. The precious canvases were shown for the first time at a large evening party, and the two hosts themselves led the most influential connoisseur and art critic up to the wall on which the portraits were hanging side by side. He studied the works for a long time, and then, shaking his head, as though there was something he had missed, pointed to the gap between the pictures and asked quietly: ‘But where’s our saviour?”’ (Freud, 1905a).

            Freud explained that the connoisseur’s Id wanted to express to the businessmen that they were thieves, however, his superego stopped him from doing so. Thus, because of resistance, repression occurred. But, instead of being expressed as symptoms of hysteria, the mind found that it could articulate this by means of a joke. This means that jokes allow repressed material to come forward without breaking the superego’s rules. In other words, the connoisseur was able to insult the businessmen without offending them.

The lectures thus far have shown that the everyday activities such as telling jokes, speaking about memories, and talking about the first thing that comes to mind, helps patients relieve repression and, therefore, remove their hysterical symptoms. Additionally, Freud has stated several ways in which the dynamics of the mind are evident, such as repression, substitution, and resistance. Moreover, there is another one that Freud has not talked about yet. This is another type of repression, namely when a patient cannot think or say anything more.

            Freud asserted that not only sets of ideas that come from the Id and are incompatible with the superego are repressed, but also thoughts that are difficult to distort or the one where their association would become obvious. This is why, Freud argues, sometimes subjects report that they cannot continue with their free association, which is the process where patients talk about the first thing that comes to their mind.

            Another method in which psychoanalysts explore the unconscious, besides free association, is by dream interpretation. This becomes evident when Freud states that “dreams are the royal road to the unconscious” (Freud, 1900). 

            He discussed how the dreams of adults may seem like random nonsense, nevertheless, the ones from children are displayed clearly like wish-fulfillments that were not satisfied the day before. Additionally, he explained that it the same concept applied to adults’ dreams, however, the content is distorted. In other words, dreams are the disguised wish-fulfillment of repressed wishes.

            In addition, Freud separated the dreams into two types of content: manifest and latent content. The former is what is visible in the dream. In other words, the physical representations present in the dream, this material comes from what happened the day before. The latter are the unconscious ideas that are represented by the latent content. He continues his lecture by saying that the unconscious material is being repressed when people are awake, however, when individuals sleep the mechanism that restrains thought from entering the conscious is weakened. Moreover, patients have to free associate to the manifest in order to understand their unconscious repressed material. Additionally, there are two more mental processes occurring in the dream, they are condensation and displacement. The former has already been discussed, this refers to how the manifest content could represent several latent elements (Encyclopædia Britannica, 2016a). The latter is a defense mechanism. Displacement when a wish that can be fulfilled in a way redirects its attention to be satisfied in another (Encyclopædia Britannica, 2016b). For example, if a repressed desire is ultimately disappointed in the waking life, individuals dream about it, thus redirecting how the wish is accomplished.

            In the last part of his third lecture Freud discussed the topics explored in his book “Psychopathology of Everyday Life.” He asserted that concepts like repression and resistance are not only components of patients that live with hysteria, but they occur every day on everyone. Other concepts include the inability to recall something even when it is known, the slips of the tongue (now known as Freudian slips), as well as reading or writing wrongly (Freud, 1904). These mechanisms serve the same purpose of expressing an unconscious repressed desire from the Id.  Freud argued that sometimes repressed material was articulated in the forms of dreams and also this type of everyday psychopathology, and thus it deserved to be called a symptom.

            In his fourth lecture, Freud talked about the discoveries made using the techniques mentioned above. Mainly, that erotic content was the principal kind of material that was being repressed in both children and adults. This evidence was the cause that made Freud report that sexual drives were innate and universal. This claim was controversial because at the time it was believed that the development of sexuality was non-present during childhood (Freud, 1905b). In addition, Freud too, at first, doubted that his assertion was correct, he mainly though that the patients he analyzed with Breuer were the only one that had a sexual component influence their pathology. However, as time passed he observed a pattern in all of his patients. Even Freud’s followers stated at first that this was one theoretical point in which they disagreed with him. Nevertheless, they ultimately found the same pattern with their own patients.

He later named the phenomenon of sexual development in childhood Oedipus complex (Lapsley, 2011). This refers to how male children are at first in love with their mothers because they are the providers of pleasure, such as food, warmth, etc. The complex also involves feelings of jealousy towards children’s fathers. This material was, obviously, repressed. To support his theory of infantile sexuality, Freud shared a paper of a faculty member of Clark University. The name of the paper was “A Preliminary Study of the Emotion of Love between the Sexes,” and it stated that the appearance of what the author called “sex-love” did not make its initial original appearance in individuals who were in their teenage years, but rather when they were just mere children. The author made 2, 500 observations that supported his hypothesis and only 800 were made by him.
            To summarize the lectures up to this point, Freud believed that there was material in the form of wishes that were either repressed or could not be satisfied. The frustrated desires were then expressed in a way that relieved the Id’s wants in several forms such dreaming, forgetting, or mispronouncing something. In his fifth lecture, Freud talked about another form of expression. This phenomenon is transference.

            Sigmund Freud explained that because a lot of wishes end in disappointments, individuals then resort to fantasies. Moreover, he added that the successful man made his fantasies a reality, but for those who did not, they ended up expressing their desires with hysterical or neurotic symptoms, as well as other psychoanalytic concepts. This included transference, which is a set of affective feelings mixed with hostility directed towards their psychoanalysts without a particular reason (Felluga, n. d.) . This allows the repressed erotic material, as well as the aggressive one, to take place while complying with the set of rules of the superego.

            Freud claimed that transference was also seen in the everyday life of all human relationship like forgetting and misspelling. And that this was the implicit way human beings engaged in a therapeutic procedure in order to relieve tension caused by the dynamics between the Id and Superego.

            There were three possible outcomes after the repressed material was made conscious. The first one is that the individual replaces their repression with a condemning judgment about their unconscious material. The second result that is possible after psychoanalytic therapy is that now that the individual understands what drives him or his Id’s desires, the subject can engage in a behavior that is similar to the defense mechanism known as sublimation. This refers to finding socially accepted activities that permit the person to indulge his or her desires without disobeying their superego. An example of this is identifying the drive that motivates someone to engage in aggressive behavior, then redirecting this into an activity such as mixed martial arts. If this action takes place, then the individual is allowed to be aggressive without breaking a social rule. The third possible result would that a hysterical symptom is eliminated, while a new one appears.

            In conclusion, Freud stated that there was a constant interaction between several parts of the mind, especially the id and the superego. The dynamics mentioned above were usually unconscious and created different forms that allowed a relief in tension. These included dreams, transference, slips of the tongue, forgetting, mispronouncing, misplacing, as well as creating hysterical symptoms. The tension created by the id and superego is also relieved by psychoanalytic therapy.

Burnham, J. C. (2012). After Freud left: A century of psychoanalysis in America. Chicago: University of Chicago Press.

Felluga, Dino. (n. d.). "Modules on Freud: Transference and Trauma ." Introductory Guide to Critical Theory. Purdue U. Retrieved April 27, 2016, from <>.

Freud, S. (1938). An Outline of Psychoanalysis. New York: W.W. Norton.

Freud, S. (1909). Five lectures on psychoanalysis. New York: W. W. Norton & Company.

Freud, S. (1905a). Jokes and their relation to the unconscious.

Freud, S. (1900). The Interpretation of Dreams.

Freud, S. (1904). The Psychopathology of Everyday life. New York: Norton.

Freud, S. (1905b). Three contributions to the theory of sex. New York: Dutton.

Gray, R. (n.d.). Freud, "Aetiology of Hysteria" Retrieved April 27, 2016, from

Jay, M. E. (2016). Sigmund Freud. Retrieved April 27, 2016, from

Lapsley, D. K. (2011). Id, Ego, and Superego. Retrieved April 27, 2016, from & Chapters_files/Entry for Encyclopedia of Human Behavior(finalized4 Formatted).pdf

Rana, H. (1997). Sigmund Freud. Retrieved April 27, 2016, from

The Editors of Encyclopædia Britannica. (2016). Condensation. Retrieved April 25, 2016, from

The Editors of Encyclopædia Britannica. (2016). Displacement. Retrieved April 25, 2016, from

The Editors of Encyclopædia Britannica. (2016). G. Stanley Hall. Retrieved April 25, 2016, from 

Thursday, April 21, 2016

Introduction to Psychobiology Part 4 (Psychopharmacoloy/Drugs)


For more information about biopsychology, please check out "Physiology of Behavior" by Neil Carson.

Drugs. Today we are going to talk about drugs. Psychopharmacology is the study of drugs (now it sounds redundant). We are going to explore how they affect mental processes and behavior.

Let's start with the basics: what is a drug? Neil Carson, the author of "Physiology of Behavior" defines a drug as "an exogenous chemical not necessary on normal cellular functioning that significantly alter the functions of certain cells of the body when taken in relatively low doses (1)." Or in simpler terms a chemical that changes the normal functions of the body. We'll tackle this definition one step at a time. Exogenous means outside an organism (2). This makes a reference that there are chemicals inside the body that alters normal somatic functions, but the definition of drugs only focuses on the external ones. We use the term drug effects when referring to these changes caused by drugs. The places where the chemicals attach in order for these changes to occur are called sites of action. The phrase "functions of certain cells of the body" is stated to explain that the focus is, obviously, biological in nature. Finally, the last part, the one about low doses, makes a reference of how almost any substance that is taken in large doses affects the normal cellular process.

By using this definition we can state that coffee is a drug because it has caffeine, which is an exogenous (remember that this means that it comes from the outside of our body) chemical, and when taken in small doses it changes the normal functions of our body by giving us energy and other things. People usually have the idea that drugs are illegal and negative things that only criminals do. Do you remember the phrase "Say no to drugs?" Well, drug effects are also used to help people in the form of medicine. Remember that the stores that sell medication are called drug stores. So, our focus will not deal with the morality of using drugs, but rather with descriptive, non-normative details that surround them.

Where can drugs be administered?

We'll cover five types of ways drugs can be administered. The first one is by means of injection. Moreover, there are several types of injections, one of them is intravenous (IV) injection. This one goes right in to the bloodstream so the drug effects are instantaneous (3). The peritoneal injection, which is administered in the peritoneal cavity (duh!). This is a semipermeable wall in the abdomen (4). The next injection is intramuscular, which is delivered into the muscles and the last one is the subcutaneous injection, which is delivered under the skin (5). The cartoon to the right depicts a peritoneal injection.

The second route to administer a drug is by oral administration. Researchers don't usually use this method for two reasons. The first one is that if the experimenter is dealing with animals, they (the animals, not the researchers) might not want to consume the drug because of its flavor. The other reason is that the chemical can be destroyed by a stomach acid (1). Nevertheless, this method can be used with humans if it is administered with a sublingual method (This means placed under the tongue). In this way, the drug enters the bloodstream, thus, not being affected by the stomach acid.

The third method is called intrarectal and it is administered through the anus (6). I hope you can understand why I didn't put a real photo here. It is important to note that because of they way it is introduced into the body, many researchers opt out of his method. Nevertheless, it is commonly used with humans.

Inhalation is the fourth method. Drugs like marijuana and nicotine are usually smoked (1). This method is efficient in the sense that a lesser dose is needed for the same effect when compared to the other methods such as oral administration (7). The last method is called topical. This is applied to surfaces of the body such as the skin (8). Maybe you have seen this in the form of nicotine patches.

Finally I want to leave you a link of an artist who drew 30 portraits of himself after consuming thirty types of drugs:

Feel free to leave comments, questions, concerns, or suggestions. Thanks for reading!

1. "Physiology of Behavior" by Neil Carson








Tuesday, April 19, 2016

Introduction to Psychobiology Part 3 (Supporting Cells)

Anterograde and Retrograde Axoplasmic Transport

For more information about biopsychology, please check out "Physiology of Behavior" by Neil Carson

Before I start I want to cover axoplasmic transport

If you saw the pictures from part 2 (, there was something called microtubules that we did not cover. They are a bundle of protein filaments with two main functions (1). One of them is to form the cytoskeleton, which gives each neuron its shape. The other function is to engage in axoplasmic transport. This is the process in which substances are transported along the axon. Kinesin, which is a protein, carries the substance. If the movement is from the body of the cell towards the terminal buttons, the process is called anterograde and if it is from the terminal buttons to the soma it's called retrograde transport (Antero- means towards and retro means backwards).

Supporting Cells

Most people think that neurons are the only type of cells on the brain. This is not true. There are cells such as glial cells that support the neurons in different ways. For example, the type of cell mentioned above holds neurons together (glia means glue) and provides nutrients (2). 

There are three main types of glial cells. they are astrocytes, oligodendrocytes, and microglia (3). The first cell got its name because of its shape (astrocyte means star cell) and it is responsible for delivering nutrients, as well as controlling the development of neurons (4). Another function is to engage in a process known as phagocytosis. This procedure involves astrocytes cleaning up any cell in the central nervous system (CNS) that dies. 

The second type of cells, which are oligodendrocytes, produce an insulating sheath called myelin that covers the axons of neurons (5). The points at which the axon is not insulated are called nodes of Ranvier. 

The last cell is microglia. They also engage in phagocytosis (did you remember that this was the process of cleaning up dead cells?), as well as acting as one of the parts of the immune system in the CNS (6). If you paid close attention, you noticed that we have only covered supporting cells in the CNS, well, not anymore. In the peripheral nervous system (PNS) Schwann cells perform the same functions as oligodendrocytes cells (7) from the CNS (remember that the central nervous system is encompassed by the brain and the spinal cord).

The Blood Brain Barrier

An important thing to mention is the blood brain barrier. This refers to the barricade that separates the brain and the vascular system (8). The BBB is semipermeable, this means that some substances are able to pass through it (2). The barrier has some gaps were substances are able to come in and out of the vascular system. Another part, besides the small gaps, where substances can travel through the barrier is the postrema, which is the section responsible for vomiting. In this area, neurons can detect poison in the blood and thus induce vomit (9).

Feel free to leave comments, questions, concerns, or suggestions.


2. "Physiology of Behavior" by Neil Carson.






Sunday, April 17, 2016

Introduction to Psychobiology Part 2 (Internal Structure of Neurons)

Internal Structures

For more information about biopsychology, please check out "Physiology of Behavior" by Neil Carson.

In part one we explored the parts of neurons, now we will look inside of them. Maybe you will remember this if you ever took biology. We'll start from the outside and end up on the center of the cell. 

First we have the membrane, which is a double layer of lipid molecules that mark the borders of the neurons. Like a customs officer, it is at the point of entry and decides what comes in and what comes out. 

Then we have the cytoplasm, which is a semi-liquid (thick) substance inside of the cell (1). The enzymes act as a catalyst to either separate or unite substances.

Ribosomes are produced by the nucleolus and they are responsible for the production of proteins (2) translated from mRNA ((1) We call this process protein synthesis). Chromosomes are made up of proteins and a single molecule of DNA ((3) Short for deoxyribunocleic acid). They are found in the nucleus. 

DNA is usually found in the nucleus (it can also be found in the mitochondria) and it contains genetic material (4). The mRNA is the carrier of genetic codes from the DNA in the nucleus to the ribosomes ((5) remember they translate it into proteins). Mitochondria are organelles (little organs) that convert oxygen and nutrients into adenosine triphosphate (ATP(6)), which helps with energy metabolism (when it is broken down it liberates energy (1)).  

More organelles include the Golgi apparatus. This is responsible for transporting proteins and it's located close to the endoplasmic reticulum (7). 

The latter has two forms: smooth and rough endoplasmic reticulum. It is a membrane that has several functions, three of them include the transportation, synthesis, and modification of proteins (8). 

The Golgi apparatus also produces the lysosomes, which are sacs full of enzymes (remember that enzymes either break or unite substances by acting as a catalyst).

And finally the nucleus, in which DNA can be found. It contains the nucleolus and chromosome (1). It usually has a round shape and it is found at the center of the cell, protected by the nuclear membrane (1).

Here is a picture of an axon terminal that was cut open taken from an electron microscope. 
This has to be one of my favorite pictures!

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1. "Physiology of Behavior" by Neil Carson








Saturday, April 16, 2016

Introduction to Psychobiology Part 1 (Neurons)

Structure and Functions of Cells of the Nervous System

For more information about biopsychology, please check out "Physiology of Behavior" by Neil Carson.

We'll start the series by talking about the structures of the nervous system. Let's start with neurons. They are cells in the central nervous system (CNS) that process information (1). There are several types such as sensory neurons, which receive info from places such as the skin and sends it to the CNS (2), motor neuron, which sends info to places such as muscles so they can move, and interneurons, which are located between a sensory and a motor neuron (4).

Fun Fact: It is estimated that there are around 100 billion neurons in the brain (4)

We already talked about the CNS, but what is it? Well, to put it simply, it is composed of the brain and the spinal cord. If you noticed that there is a CENTRAL nervous system, then there should be one not so central. This is called peripheral nervous system (peripheral means outside), and it's every part of the nervous system that is outside of the brain and spinal cord.

Let us go back to neurons and talk about their parts. The structure of a neuron depends on its type, however there are similitudes between all of them. These include the soma, which is the cell body of a neuron, the dendrites, which look like tree branches and receive information, an axon, which is the part of the neuron that sends info, the synapse, which is the space between a terminal button and a dendrite.

Types of neurons

The most common type of neuron is called multipolar (3). This has one axon and many dendrites attached to its soma. A bipolar neuron has an axon from one side and a dendrite from the other.

Bipolar Neuron

Another type is the unipolar neuron. This cell has only one stalk that divides into the axon and the dendrites. Bipolar cells are usually found in sensory systems such as vision. Unipolar neurons usually work with somatosensory functions such as feeling pain and temperature (5). Both of them receive information from the physical world and send it into the CNS.

One way of sending information is with neurotransmitters. They are released by the terminal buttons when an action potential happens. A neurotransmitter is a chemical that has an effect on another neuron (remember how the synapse is the space between a terminal button and a dendrite? Well, when the neurotransmitter is released it travels in this space in search of a receptor usually on a dendrite of another cell) either by inhibiting or exciting it. This is how neurons communicate.


Physiology of Behavior by Neil Carson