The last section in this semester of Behavioral Neuroscience covered “Special Topics in Mental Disorders.” For this topic Eric separated the class into four groups. Three of the groups presented their topics to the class during lecture times this week (Monday, Wednesday, and Thursday during an hour of lab) with that material being covered in this week’s exam. The fourth group, which was my group, presented the following Monday as it was the last week of classes and Wednesday was the last class meeting day of the semester. The exam covering our topic was on that Wednesday.

The topic my group presented on was posttraumatic stress disorder. It is caused by some type of traumatic event or stress such as rape or war. It involves reliving the event in some way such as flashbacks or nightmares that prevent a patient with posttraumatic stress disorder from dealing with the problem effectively and moving on with their life. The disorder was broken down into components like behavioral changes, treatments, and brain changes. My section was brain changes.

Learning about the brain changes was rather interesting because it is so complex. Much research investigated the involvement of the hippocampus, which makes sense because the hippocampus is involved in memory processing. A link was found between hippocampal volume (the size of the hippocampus) and developing posttraumatic stress disorder. However, the link was not super clearly defined. One study looked at the brains of police officers, all of which had gone through the traumatic events of serving their community, and found that officers with posttraumatic stress disorder had smaller hippocampal formations. This establishes a connection between the hippocampus and posttraumatic stress disorder but the connection gets more complicated. There was a different study looking at Vietnam War veterans who developed posttraumatic stress disorder and who also had a monozygotic (identical) twin who did not serve in the war. The results showed that the veterans with posttraumatic stress disorder had smaller hippocampal volumes, which was to be expected. However, the interesting part is that the twin who did not serve in the war also had a smaller than average hippocampal volume. This implies that having a smaller hippocampal volume is a predisposition for developing posttraumatic stress disorder.  I read about a third study looking at a different group of veterans and their brains. This study found more evidence supporting the connection between decreased hippocapmpal volume and the development of posttraumatic stress disorder. However, the results showed that the decrease in hippocampal volume was proportional to the amount of time the soldier had served in armed combat. This suggests that trauma has a causal role in the shrinking of the hippocampus. Clearly we have a lot more to learn about the disease and there are many more important factors than just the hippocampus but I found all of that rather interesting.

This week in Behavioral Neuroscience we discussed different neurological disorders. This topic tends to be rather sad or depressing but it is still very important to understand. The first topic we discussed was tumors. A tumor is a mass of cells that are dividing uncontrollably. Tumors can be either benign or malignant with the difference being that benign tumors are encapsulated but malignant tumors are free to divide and spread as they are not contained in any type of encapsulation. One of the main concerns about tumors is the possibility of malignant tumors spreading and causing cells in other areas to divide uncontrollably causing damage. Benign tumors cannot do this but in the brain they can cause damage in another way. If the tumor is big enough it can cause compression damage on brain structures adjacent to it as there is only a finite amount of space inside a skull. However, benign tumors can be removed surgically which is way easier and has less negative effects than the alternative. Due to the fact that malignant tumors are free spreading they cannot be surgically removed and require radiation treatment or chemotherapy. This can cause damage to healthy brain cells and the hippocampus is the first to be effected. This is why memory loss is common with high doses of these treatments.

We also talked about other types of neurological disorders this week like strokes and mental health but the one that I found most interesting to learn about was seizures. A seizure is defined as “a sudden and uncontrollable burst of activity in cerebral neurons.” Sometimes a person having a seizure will tense up an convulse and that is caused by a seizure in motor neurons. There are different types of seizures and we learned about a few of them. However, the most interesting one for me was the Grand Mal seizure. In this case “Grand” means “great” or “big” and “Mal” is taken from the latin root for “bad”. This means a “Grand  Mal” seizure is really a “Big Bad” seizure. A grand mal seizure occurs in stages. The first stage is called the “Tonic stage”. This is when you see complete muscle contraction in the body of the person having the seizure. This stage lasts for about 15 seconds. After this the person enters the “Clonic stage” which is characterized by periods of twitching and trembling, violent grimacing and eyes rolling around in their sockets, and sympathetic nervous system activation. This stage lasts for about 30 seconds. Now the stages are nameless but the next stage involves the muscles relaxing and breathing resumes. The person will experience a loss of consciousness and this will last for about 15 minutes. After this the state of consciousness will shift to an altered consciousness similar to a sleep-like state and this will last for the next 3 to 4 hours. All things considered, I fell like the Grand Mal seizure has earned its name and I am glad I have never experienced one and hope to never have to in the future.

This week in Behavioral Neuroscience we discussed learning and memory. The very first thing to know about this week’s topic is there really isn’t a difference between learning and memory. As Eric stated in class “learning is altering memory and memorizing is learning.”

Learning is categorized as Associative and Non-Associative but some neuroscientists have a problem with that. Our nervous system utilizes time and space as the two primary factors for it to function. This means that everything sensed and perceived has a “timestamp” which means it is associated with that time. In this way it may not be possible for anything to be Non-Associative.

Whether you agree with Non-Associative learning or not all learning depends on habituation. Habituation is defined as “a decrease in responding based on repetition of experience.” Habituation is the reason you were enjoying your music in the car at a “reasonable volume” last night but then in the morning when you turn your car on the music is blaring. The previous night you habituated to the volume and increased it incrementally over the car ride as you desired. However, when you re-entered the car you had not habituated to the music again and it was much too loud. Habituation must be present for one to say learning has occurred. Learning is defined as a relatively permanent change in behavior based on experience.

If habituation exists as a change in behavior then there is probably a change in behavior that is a sort of opposite of habituation. There is and it is called sensitization. Sensitization is defined as an increase in responding based on experience with new information. Sensitization and habituation are the only things that could be considered Non-Associative learning.

Classical conditioning is the simplest form of learning. In classical conditioning there is a stimulus that will elicit a response that is natural and does not have to be taught. This is called an unconditioned stimulus (US) and unconditioned response (UR). The learning is involved when a second stimulus (known as the conditioned stimulus or CS)  is present for the UR . Now that US is enough to elicit the unconditioned response but now it is called a conditioned response (CR) because it is elicited by the CS.  Classical conditioning has five different components which are acquisition, generalization, discrimination, extinction, and spontaneous recovery.  Acquisition is taking on a new conditioned response or behavior that is connected to a conditioned stimulus in the environment. Generalization is expressing this behavior for stimuli that are similar to but not exactly the same as the conditioned stimulus the behavior was acquired for. Discrimination is a lack of responding to stimuli with the CR because they are too different from the CS. Extinction is a reduction in responding with the CR based on new experience with the CS. Spontaneous recovery is a resume in CR after time has passed after extinction.

This week in Behavioral Neuroscience we covered emotion. This was a really cool week because we got to talk about two of my favorite topics in all of neuroscience and psychology. Those two topics would be the most unfortunate case of Phineas Gage and a theory brought to us by Solomon and Corbit called the “Standard Pattern of Affective Dynamics.”

Let’s start with Phineas Gage. The story of Mr. Gage serves as an example of the importance of the ventromedial prefrontal cortex (vmPFC) in controlling emotional behavior. Phineas Gage was the foreman of a railway construction crew in the mid 1800s. He held this position because he was known to be level headed and in general the type of person you want to be leading your workers in their jobs. One day while on the job Phineas Gage was very seriously injured. The crew was blasting away rock to lay down the tracks which involves drilling holes into the rock and packing the whole with explosive charges to blow up the rock. Mr. Gage was packing a charge in one of these wholes with a steel rod when a spark from the rod being jammed into the whole sparked the charge and sent the pole up into his left cheek and up out the top of his head. The resulting injury was a whole clean through his head that went right through the vmPFC. Miraculously Phineas Gage survived this incident but he was never the same again. Once he had physically recovered Phineas Gage went looking for his old job again but he was unfit for duty. The man who was previously known to be level headed and reliable was now described as childish, inconsiderate of others and inconsistent in making and following through on plans with others. That is a real example of how physiological damage in the vmPFC can affect emotions.

The Standard Pattern of Affective Dynamics is my favorite theory I have ever learned because it is very applicable to basically every function of the human body. You can think of it as a homeostatic theory or mechanism. Basically the theory states that everything that happens in/to your body to move you away from the sweet spot for biological functions (homeostasis) is regulated by your body by applying the exact opposite force to whatever it is that moved you from homeostasis. In the theory the process that moves you away from homeostasis is called the “A-process” and the process applied by your body to counter the A-process is called the “B-process.” Your body will do this naturally but the more often the A-process occurs the faster the B-process will kick in after the initiation of the A-process and the B-process gets closer in magnitude to the A-process making them “cancel each other out” more completely. In lecture Eric likes to use love as the example for this and it is quite entertaining. He will tell a story about one of the students in the class. This student is minding their own business when suddenly the love of their life walks in the door to the classroom. This causes the student to experience physiological changes that go along with arousal like sweating and feeling “butterflies” in the stomach. However, because the presence of the love of this person’s life is the A-process causing this physiological arousal the feelings are gone once the love of the student’s life leaves the room. Of course, because this is the love of that student’s life they go find this person again and eventually get married. They now get used to living with the love of their life and associate many things about their life together with the person that is the love of their life as they are together so often. However, now over the years the physiological signs of arousal aren’t there anymore. This is not because the love of their life has lost their effect as the A-process but rather the B-process has become more efficient and is consistently working to counter the A-process. This brings us to the last application of the Standard Pattern of Affective Dynamics but it is rather sad. One day the love of the student’s life dies. They are gone and never coming back which means the A-process is never coming back either. However, the student’s neurology doesn’t know this so the B-process continues as it did before causing a consistent effect that is the opposite of arousal. This explains why elderly couples often die within a year or two of each other.

This week in Behavioral Neuroscience we covered movement. In lecture we began by watching a TEDtalk by a man named Daniel Wolpert in which he discussed the reason why humans and other animals have brains. He said the number one reason we have brain is “to produce adaptable and complex movements.” As someone who considers himself to be a behavioral neuroscientist I am inclined to agree. Movement is the only way for us to influence our environment which is critical for our survival. You can imagine how problematic it would be for humans to be able to recognize a train is coming down the tracks that they are standing on but then lack the ability to move off the tracks. In fact coding and executing behavior in artificial intelligence is more challenging than coding and executing cognitive processes. As technology is currently, computers are much faster and better than humans at the strategy of chess but computers are not nearly as smooth and precise as humans at actually moving chess pieces on a chess board.

We then moved on to learn about muscles which are the organs that cause the body to move. Muscles are thicker in the middle than they are on the edges to allow for greater movement when contracting. Muscles are made of two types of muscle fibers. Ex may represent a lack of motor inhibition,
during goal-directed cortical activity, with release of
inappropriate instinctual activity. usal fibers are on the outside of the muscle spindles and are connected to alpha motor neurons while intrafusal muscle fibers are found inside the muscle spindles and are connected to one motor neuron and one sensory neuron. The two types of fibers form a structure called the muscle spindle and it was named so because the researchers who first found it thought it looked like a spindle for spinning thread. Extrafusal fibers are primarily responsible for the contraction of the muscle when stimulated by the alpha motor neuron while the intrafusal fibers are primarily sensory organs. They can contract as well but intrafusal fiber contraction serves mostly as a way to modify the sensitivity of the fiber’s afferent ending to stretch.

Most movements are executed as a result of a command coming from the primary motor cortex in the brain. However, in addition to the primary motor cortex there is also a premotor cortex, pre-supplementary cortex, and supplementary cortex. Each of these is activated by different types of movements. The premotor cortex is activated by arbitrary commands. An example of this from class would be when Eric instructs all the students to “turn to your neighbor and discuss” whatever it is that we just went over in lecture. That instruction activates the premotor cortex. On the other hand the supplementary motor cortex is activated by conscious thought or planning of movement. This includes learning and executing sequences of movement like ballroom dancing (which we did in lab to demonstrate how difficult these movements can be) or basketball/football plays.

This week was a short week because it is fall break. We only had three days of class this week but due to Tuesday taking on the Thursday class schedule we were able to have lab on Tuesday and this weeks exam is a take-home exam so we could have lecture on Wednesday still and get a full three lecture week in on somatosensation. Also it is important to note that Eric gave us a chance to demonstrate our understanding of what was discussed in lab on Tuesday and those of us who were able to regurgitate enough information are exempt from taking this week’s take-home exam. Eric is an absolute “O.G. Homie” for that!

Somatosensation can most simply be described in laymen terms as the sense of “feeling”. This includes but is not limited to the sense of touch. The sense of touch is what monitors our interface with the environment. Thus, as a general rule, anything that has greater interface with the environment has higher sensitivity to touch. This means body parts like hands, feet, lips, and external genitalia have a higher sensitivity to being touched than an earlobe or a kneecap. If you want a real-life example of this you can do an activity we did in the first day of lecture if you have a partner to do it with. All you need is two pointed objects (we used nails) and a ruler or measuring device of some sort. Have one person take the two pointed objects and apply pressure on a body part of the other person in close proximity to each other. The person who owns the body part must be looking away for this to work. If they are close enough together it will feel like one object is touching you. The objective is to keep doing this while increasing the distance between the two objects ever so slightly each time until it is perceived as two objects touching you rather than one. Now measure the distance and repeat with a different body part. It was kind of fun to see what was most sensitive on my body. For my partner and I the lips were the most sensitive followed by fingers and palms. Our ankles were not very sensitive.

As I said before the sense of “touch” is not the only somatosense we have. The somatosenses include cutaneous senses (what I was talking about before as the sense of “touch”), proprioception which is sensory information about your body location and orientation in space, kinesthesia which is sensory information about how your body is moving in space, and finally organic senses which is information coming from in and around internal organs. All of these senses are similar in that explaining any of them likely involves using the word “feel” to describe it but they each serve a very distinct purpose and have different anatomical structures to help produce them.

This week’s topic of discussion is pain and gustation. The gustation section of the chapter is rather short and we did not spend a ton of time in lecture on it so I will talk about pain.

There are many different types of pain. Some specific examples from Eric’s lecture are pain from gallstones, pain from kidney stones, pain from childbirth, and pain from having your skull cracked by a plate stemming from an argument over french fries. With so many different types of pain it is important to have a good definition of pain and the process of getting that definition was not quick. Eric was in attendance at the 1993 World Congress where they had “The Great Pain Debate” in which professionals from all around the world argued over what pain should be defined as. Apparently it was like a week long ordeal. Either way the end result was this definition of pain: an unpleasant physical or emotional experience associate with actual or potential tissue damage or described in terms of such damage.

There are three components to pain. There is the sensory component that most people think of when they hear the word “pain”, there is the emotional component of pain and there is also the cognitive evaluative component of pain. In the 1960s Ronald Melzack became the first person to start thinking about pain in this way and there is physiological and anatomical evidence to support that. The sensory part of pain is mediated by a pathway from the spinal cord, through the ventral posterolateral thalamus and to the primary and secondary somatosensory cortex. The immediate emotional response is mediated by a pathway that reaches the anterior cingulate cortex (ACC) and the insular cortex. The long-term emotional component or the cognitive evaluative component reaches into the prefrontal cortex. I just love how complicated pain processing is and how many different areas of the brain are involved. Pain is super important for our survival because if we did not feel pain we would not have any positive punishments to tell us when we have done something deleterious to our health and are way more likely to continue that behavior until we die. That importance is definitely reflected in the physiological and anatomical structure of pain.

The topic of discussion for this week is research methods. Eric made a special point to emphasize the three different types of research methods in neuroscience so I am sure that will be on the exam at the end of the week. Those three areas are anatomical research, chemical research, and physiological research. All three are important and must be used together to find accurate information. All three provide different perspectives on the same neurological phenomena and taking one perspective as true over the others will not give you an accurate understanding of what is actually happening.

If we are looking at the brain and want to know what is connecting to what we can use chemicals to reveal the anatomy. Injecting a drug called PHA-L into a region of the brain allows dendrites and cell bodies in that area to absorb it from the extracellular fluid. The PHA-L is then taken down the axons to the terminal buttons via axoplasmic flow. Now when we find the PHA-L we will know where the cells in the area we are interested in connect to.

We also talked about other research methods like testing pain physiology in rats with tail flick tests, hot plate tests, and using formalin injections which create painful inflammatory responses. We talked about lessions in the brain and how purposefully doing that to rats can show us how the brain works. However, it is important to know how the lession was made because different lessions effect different structures in the brain. Microdialysis is another research method discussed in class that uses a semipermeable membrane on the end of a cannula that is used to extract the fluid from between cells. This can give us information about the neurotransmitters being sent and received in that area. Autoradiography, like x-rays, can give us pictures of the brain as another research method.

This week we are learning about psychopharmacology. That means this weeks chapter is covering different types of drugs and their effects, drug administration techniques, sites of activation, different types of receptors and neurotransmitters. Much of what we have been learning up to this point has been a review for me and other students in the class who have taken other neuroscience and psychology classes but this chapter is a lot of new material and it is complicated.

The first order of business in class was to define the word “drug”. As we use the word “drug” in class it means an exogenous chemical compound that interacts with the cells of the body. This gives drugs a very broad categorization which can include things like pizza and chocolate as both foods can directly and indirectly release dopamine in our bodies. Other important terms defined in class were site of action, the locations at which a drug interacts with molecules on or in cells of the body, and drug effects which are the changes produced in an animals physiological processes and behavior.

We talked about different ways to administer drugs such as intravenous injection (IV) which most people are familiar with, intraperitoneal injection (IP) which involves an injection going into the space surrounding the stomach and other abdominal organs, and  intramuscular injections (IM) as well as drug administration forms that do not involve injections like topical administration and sublingual administration which is administering a drug under the tongue.

Some drugs have effects that are not intended to be consciously noticed by us when we use them, such as drugs that change our body chemistry to alleviate noxious internal stimuli, but that is never the case with recreational drug use. The point of recreational drug use is for us to be consciously aware of the effects of the drug and typically those effects are positive for the drug user “or at least interesting” as Eric put it in class.

We talked about many other things in class like margins of safety for drugs, tolerance and sensitization, withdrawal, placebo effects, and different ways drugs can affect synaptic transmission but I want to leave you with one random fun fact Eric dropped on us in lecture this week. When cocaine is injected intravenously 20% of it is in the brain in the first 30 seconds! That is why IV injection is so popular with recreational drug use but it is also very dangerous too.

Weeks 2 and 3 were originally supposed to be done separately however with the professor being gone unexpectedly for week 2 the material covered over the two weeks is actually the same material. We are continuing our review of neuroanatomy but this review is focused on central nervous system (CNS) structures. Most of this is a review structures of the brain but we briefly covered the organization of the spinal cord as well. By far the best part of reviewing the structures of the brain was our sheep brain dissection. Finding some of the structures was kind of difficult especially because they required us to make very precise and proper cuts. I had never used a brain knife before but we learned the proper technique for holding it and the angle to cut at.

Dissecting a brain is quite difficult because it is a very soft organ. The tissue will often rip as one is trying to cut it. A brain is also not very flat on most sides so it rests on flat surfaces in a way that does not keep the planes of the brain parallel or perpendicular to the ground. Holding the brain at the right angle while cutting it can be tricky because they are very soft and slippery. I also quickly found out the cuts get increasingly harder to make as the pieces of the brain being cut get smaller and smaller.