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Movement Intention After Parietal Cortex Stimulation in Humans

Main Points – The point of the experiment was to determine the intention vs action parts of the brain. There are different parts of the brain that when stimulated, make the patient feel a strong will to move a certain region. The regions in the right inferior parietal regions made patients want to move their hand or feet, whereas stimulating the left inferior partial made them want to move their mouths. They also did further stimulation and found patients believed they had moved or talked.

Methods – The method used for this experiment was using electrical stimulation to trigger certain parts of the brain while the patient was undergoing brain surgery for which they were awake. These were all tumor patients.

Shortcomings – This experiment is limited by the amount of people that undergo this type of procedure and it is all based on their responses. There isn’t physical data; the results are based on how the patient describes these sensations.

Figures – The figures are used to demonstrate where the brain was stimulated and makes the experiment easier to visualize.

Questions – It seems that a major question posed was whether the intention or the action came first. The article touches on this briefly, but its hard to tell if they came up with a solution. And how much of this experiment was based off educated guesses or was some of this information known? What is the new information?

Keywords – inferior parietal, intention, cortex, stimulating, SMA

Shh is a cell-cell signaling molecule that has been conserved between all vertebrates. Shh has been shown to be a vital part of driving cell differentiation in other areas of the body. This experiment will allow for a better understanding of the effect of sonic hedgehog in the developing, which will provide insight into the control of cellular development, the cell cycle, and of diseases such as cancer. This will be accomplished using the Tet-On system, a system designed to control transgenes. The genes are unable to be transcribed until the binding of tetracycline or a tetracycline derivative (such as doxycycline) to an activator protein. The addition of the doxycycline allows transcription to begin, giving very tight temporal control. The design of the experiment is to observe the effects of activating the transgene at different time points, ranging from 4 hours post fertilization (hpf) to 48 hpf.

Canis latrans, Canis lupus, and Canis familiaris are separate species. Ernst Mayr defined species as "groups of interbreeding natural populations that are reproductively isolated from other such groups". The article describes how Canis latrans have been known to interbreed with Canis lupus and Canis familiaris, which, by Mayr's definition, would mean that all three are the same species. However, the article states that the notion that an inability to breed defines what a species is has been abandoned by many scientists. Hybridization is the process of interbreeding from genetically distinct populations to produce a hybrid, and therefore it occurs across different species. This is what is happening when Canis latrans interbreeds with Canis lupus and Canis familiaris. Homo sapeins are hybrids themselves because it has been proven that there was interbreeding among around four species of early humans.  

My grandma sponsored my mother and I here to the U.S. We had to part with my dad when I was 2. They got divorced after my mom sponsored him here because my dad felt he was being wronged by my mom. He never paid for child support and fled. That was disappointing since we were the ones to always care for him. We sent him money every month while we were separated for 7 years despite how poor we were and how much we were struggling. All my life, I’ve been raised by a single mom. She had to work hard in order to provide for my 2 sisters, myself, and my grandma. My mom says I must carry the burden of being the eldest daughter while being the first to go to college in the family. I’ve always had to translate and explain just about everything to my mom since I was young. She does not speak nor understand English well. It gets stressful at times because I would from time to time, not understand the things she’s trying to do (mortgage, insurance, taxes, financial matters, etc.). Therefore, I couldn’t understand what the people were trying to tell her in return. I had to develop people skills in order to ask others in a polite manner to help us. I had to learn how to talk to people and interact well with them. That was how my family was able to keep going with our lives, asking others for help when we needed it. They say students are scared to ask questions because they don’t want to look dumb. I guess that’s why I’m able to ask questions all the time because I’ve had to do so my whole life in order for my family to survive.

I will do my panel on Hymenocallis littoralis, or the Spider Lily. I chose this plant because it stood out to me as I have an irrational fear of spiders. This plant is native to the warmer coastal regions of Central America but have also been introduced in Florida. It ranges from a height from 60-70 cm, or 36 inches. The bulb has a diameter of 7-10 cm, or 3-4 inches. The neck that grows from the bulb has a length of 4-5 cm, or 2 inches. Each flower’s tube ranges from 14-17 cm, or 5-7 inches. The flowers that blossom off of this plant are white, vanilla scented and give the shape of a spider, hence the name. An interesting fact about this plant is that all parts of it are poisonous. There are many types of this plant. In Japan, they have been used in rice patties to deter pests that can ruin the fields. They have also given it the name of “Higanbana” which translates to “flower of death”, unlike first thought, this is correlated because they have been places on tombs of the deceased as a tribute to the dead. A legend that they have the ability to guide the dead into the next reincarnation which is highly sought after in the Buddhist community. 

Pregnant women now have access to a new blood test called “cell free fetal DNA testing” that can be used to screen the DNA of a fetus for chromosomal problems. Just like all medical practices, there are some advantages and disadvantages to this new procedure. The appeal of this blood test is that it is less invasive than an amniocentesis, which removes cells from a fetus using a needle and adds a small risk for miscarriage. The downside is that despite the increased convenience of this new method, a follow up amniocentesis can sometimes be recommended because it is still the most definitive diagnostic tool if a problem is found.

Surgeons performed direct electrical stimulation under local anesthesia on patients in order to find out where the intention of actions originated from. To start off the surgeon informed the patient that a stimulation was about to start. The surgeon counted out loud to let the patient and experimenter know the beginning and end of a stimulation. The experimenter asked the patient whether he/she felt something or whether he/she moved. Other stimulations were done to determine areas potentially responsible for movement and language. It was found that even in the absence of actual motor responses, stimulation of the posterior parietal cortex caused patients to intend to move and to report having moved. Stimulation of the premotor cortex also triggered limb and mouth movements that weren’t consciously detected by patients. As a result it was concluded that motor intention and awareness are emerging consequences of increased parietal activity before movement execution. The subjective (and potentially illusory) feeling that we are executing a movement does not arise from movement itself, but is generated by prior conscious intention and its predicted consequences.

Main Points

Where in the brain are intentions and willed actions formed?

How do we become aware of these intentions?

Stimulation of the posterior parietal cortex caused human participants to intend to move and to report having moved, even in the absence of actual motor responses.

Stimulation of the premotor cortex triggered limb and mouth movements that weren’t consciously detected by the patients

Motor intention and awareness are emerging consequences of increased parietal activity before movement execution.

The subjective (and potentially illusory) feeling that we are executing a movement does not arise from movement itself, but it is generated by prior conscious intention and its predicted consequences.

Methods

Got formal consent from informed patients (with lesions) to perform the procedure

Direct electrical stimulation under local anesthesia on patients

Surgeon informed patient that a stimulation was about to start

Surgeon counted out loud to let patient and experimenter know the onset and end of stimulation

Experimenter asked patient whether he/she felt something or moved Other stimulations were done to determine areas potentially eloquent for movement and language

Coordinates of stimulation sites were recorded

IMCL content within skeletal muscle is known to be a source of energy in numerous daily tasks. The purpose of this study was to examine the effects of age and sex on IMCL contents. These lipids were analyzed using electron microscopy (EM) images of the vastus lateralis. Based on our analysis we found that there is a significant age by sex difference in lipid area in which older women had a smaller IMCL lipid area than younger women.

    According to our analysis there is also a significant sex difference in respect to lipid circularity. Specifically, men appear to have lipids which are more circular than those found in women. We suspect that such a difference can affect the efficiency of lipid metabolism within muscle fibers which can in turn affect overall muscle function.By examining such relationships we hope this data will be helpful for creating clinical interventions to improve lipid metabolic efficiency which is beneficial for overall muscle function.

    When examining the effect of sex, age, and age by sex of adults on solidity of IMCL, it is apparent that there is a significant difference across all three variables (p= 0.027, p=0.00, p=0.00, respectively). Figure 4 demonstrates that there is a large difference  between the solidity of IMCL in younger women, with an average of around 8.895, as compared to young men, and old men and women who have much higher average solidities.