ay in hefMRI stands for Functional Magnetic Resonance Imaging, and it is a noninvasive procedure that measures and maps the activity of the brain. It is derived from MRI, which uses similar procedures to create images of body tissues, and was expanded and made specific to the brain in fMRI imaging. The knowledge we have gained about the brain through fMRI is tremendous, seeing as before its proliferation about 20 years ago, we could not see the inner workings of the human brain. Now, however, we know what each area of the brain does and when it is activated during human activity (What is fMRI?, 2018).
An fMRI machine has a bed on which the patient lays, and it moves the patient into the machine, which creates a magnetic pull 10,000 times stronger than that of the earth. This causes the nuclei in the hydrogen atoms in our bodies to respond and line up, and when the radio frequency pulse is applied, the nuclei absorb the energy and transmit a strong signal detected by radio frequency coils in response to the magnetic pull. These signals from each nuclei add up so much so that they can be measured and detected. Further, when an area of the brain is in use, the blood flow to that region of the brain is increased. Neurons require more oxygen when they are in active use, so in response, blood vessels surrounding those neurons contract to allow a stronger blood flow, thus delivering the necessary oxygen to the area (What is fMRI?, 2018).
However, brain signals being measured decrease in strength after a period of time when the signals from the neurons become desynchronized. Because of this fMRI machines measure the frequency of the signals and how long they stay, and can extrapolate from this information what areas of the brain are receiving more oxygen. fMRI machines can be used in the diagnoses of many diseases through comparison of the brain scans of healthy individuals and patients. The brain maps of depressed patients, for instance, shows clear and marked differences from those who are mentally well. Future research, such as the Human Connectome Project, is seeking to understand how the different regions of the brain connect with each other to allow us to complete the myriad of tasks our brains allow us to do (What is fMRI?, 2018).
Résibois et al. (2018) used fMRI to study emotional dynamics in the brain. Past research has found different ways to describe emotional episodes. The level of emotional explosiveness relates to how quickly or slowly emotional intensity starts, and the level of accumulation describes whether the emotion increases over time or dissipates. These dimensions of emotion are found in different brain regions, wherein emotional explosiveness occurs in the medial prefrontal cortex, and emotional accumulation occurs in visceral arousal areas such as the posterior insula. These experiences have also been studied with respect to two different perspectives on the part of the subject; self-immersed, which is a first person recount of an experience, and self-distanced, in which the subject distances themselves such as in third person. The present research hypothesized that participants that took a self-distanced perspective when experiencing negative social feedback would experience lower levels of emotional explosiveness in the medial prefrontal cortex, as well as lower levels of accumulation in the posterior insula.
There 32 participants total, 18 female and 14 male, who were taken from a mailing list of French citizens who volunteer to be apart of scientific studies. In order to study this, participants filled out questionnaires in which evaluators were supposed to create a profile of the participants based on personality and whether or not they would like them as a friend.In reality, there were no evaluators, and all participants received the same feedback. Participants then were asked to lay in an fMRI scanner where they received the feedback, of which there were five negative and five neutral statements. Before each example of social feedback, participants were instructed to adopt either a self-immersed perspective, and once prompted, draw an emotional intensity profile indicating their level of emotional intensity. The X axis reflected time (up to 60 seconds, up to 30 seconds being the time they took to read) and the Y axis reflected the level of emotional intensity (on a scale of 1-7, 7 being very high). The data was analyzed through correlations and multilevel analyses (Résibois et al., 2018).
Their results indicated that explosiveness and accumulation levels were lower when participants adopted a self-distanced perspective as opposed to a self-immersed perspective, as hypothesized. This suggests that individuals seeking to resolve emotional trauma can benefit from therapy that teaches them to observe and appraise their experiences as if they are an outsider to the situation and get a broader perspective in order to reduce their level of negative affect. The research presented evaluated the data satisfactorily, although they may have benefited from a larger sample size. The fMRI scanner was used to indicate which areas of the brain were being used and at what intensity during the research. While it was not their most significant finding, the fMRI scans indicated that the self-distance perspective did not lead to altered levels of activity in explosiveness and accumulations’ respective brain regions (Résibois et al., 2018).
PET Scanning
Another type of research technique is PET scanning. The PET scanner is a large machine with a hole in the middle with rings that detect energy emission. PET stands for positron emission tomography, and it is a noninvasive nuclear imaging procedure used to diagnose ailments such as cancer, tumors, heart disease, and brain abnormalities. In order for them to work, patients are given radioactive materials called radiopharmaceuticals or radiotracers, which can be injected or given orally. The most common radiotracer, F-18, is similar to glucose in that metabolically active cancer cells absorb it quickly, which is picked up easily by the PET scanner when the radiotracers accumulate in the abnormality. This easily shows how the energy in the body is being used. The energy is given off as gamma rays and images are captured with a gamma camera, which creates pictures of organs and tissues for doctors and researchers to analyze (Radiological Society of North America, RSNA, & American College of Radiology, n.d.).
Because PET scans allow us to peer inside the body to see detailed images of where body energy is being expended, it is a common method for researchers to use to find data for their studies. When participants are given radiotracers, researchers can study the brain activity involved in many different ailments or processes, such as depression, schizophrenia, substance abuse, etc. Similarly, researchers can see if radiotracers are reaching their intended targets, which helps in the development of medicine and treatments for diseases (Radiological Society of North America, RSNA, & American College of Radiology, n.d.).
PET scanning has a number of benefits. It helps to diagnose diseases early, leaving a larger window for treatment and intervention, which could be the difference between life and death in a patient. In fact, biological markers of disease can alert a doctor using a PET scan to the ailment before the structural changes in the sick organ even occur (Yale Positron Emission Tomography). This makes them more effective than other types of scanners. On the downside, PET scanners do utilize a level of radioactive elements, and however small, this can pose a risk to women that are pregnant and limit the amount of times an individual can safely have a PET scan done in their lifetime (Radiological Society of North America, RSNA, & American College of Radiology, n.d.).
Small et al. (2013) sought to address the problem of recurring traumatic brain injuries in athletes, specifically football players. There are millions of head injuries per year that lead to a host of symptoms that can lower quality of life. One such head injury, chronic traumatic encephalopathy, leads to mood, personality, cognitive, and behavioral changes, and is characterized by accumulations of phosphorylated tau protein that can only be diagnosed in an autopsy (Small et al., 2013). To address this, FDDNP was developed, a PET probe that is the first of its kind to find tau in living humans. The research sought to find if injections of FDDNP could detect tau deposits.
Five retired football players were used in the study, as well as a control brain scan that was as close as possible to the football players in variables such as education, BMI, and age. The subjects were injected with FDDNP, and had a PET scan done. A Logan graphical analysis was used to obtain the data and the graph from the analysis was used to find the distribution volume of the FDDNP tracer (Small et al., 2013). The data was further analyzed to compare the players and the controls in terms of their FDDNP binding levels, cognition, and levels of depression.
Small et al. (2013) found that the football players had much higher FDDNP signals in multiple brain regions than the control group, proving that the tracer to find tau proteins, suggesting that chronic traumatic encephalopathy in players that experienced traumatic brain injuries could be successfully found using FDDNP with the use of PET scans. These findings are significant because it suggests that FDDNP-PET could help facilitate early detection of neurodegeneration in individuals who have suffered brain trauma, helping to diagnose and treat them quickly. This is especially important because such tests have never been able to indicate accumulations of tau protein as an indicator of chronic traumatic encephalopathy in living humans before. The research may have benefited from a larger subject pool, but due to the nature of the variables being tested, there may have been no way around it. The findings were prominent enough that the research should be referred to and expanded upon to find more ways this could prevent progression of symptoms in individuals with traumatic brain injuries. EEG is a test used to measure electrical activity in the brain for the purpose of finding problems with the brain’s functioning by means of measuring brain waves. During an EEG, electrodes are pasted to the patient’s scalp, which detects the electrical charges resulting from the brain’s activity. These can sometimes come in the form of caps that are placed all around the patient’s head. EEGs normally last about 60 minutes, however, if the test requires the patient be asleep, then it may last longer. The electrodes pick up the charges and transport them either to a computer screen or a piece of paper that the doctor reads and interprets, paying attention to the spikes in brain activity resulting from the brain’s reactions to stimuli. EEGs can be used to study a number of brain disorders, namely epilepsy, but it also can help to diagnose narcolepsy, psychosis, Alzheimer's, and other issues such as lesions on the brain that result from stroke. Because of its ability to measure electrical activity, it can be used to monitor the blood flow to the brain during a surgery (Mayo Clinic, 2018).
EEG’s can be used in research either to diagnose individuals of their ailments or to study cognition of individuals in a number of different circumstances. They can be used to help marketers understand how individuals make purchasing decisions, brain processes and how they relate to personality traits, how individuals interact with one another, and clinical and psychiatric studies (Imotions, 2013).
There aren’t considered to be many risks to EEGs seeing as they are generally very safe. They do not hurt or produce any sensations at all, however, in some cases of epileptic patients, seizures may be purposefully induced, in which case the personnel involved would be prepared to handle proper treatment. It can also induce seizures, without intention, in patients who have seizure disorders due to the flashing lights and deep breathing exercises that are done during EEGs. EEGs can measure brain activity with millisecond precision, making them a reliable and safe way to study the activity going on in the brain of either a subject of a study or a patient (Mayo Clinic, 2018).
Nikolic et al. (2018) sought to study EEG’s role in children with West Syndrome. West Syndrome is an epileptic brain disease characterized by spasms in infants, psychomotor delay, and a specific EEG pattern called hypsarrhythmia. It is structural and metabolic, and probably due to genetics. West Syndrome is one of the more difficult types of epilepsy to deal with, dependent upon the damage to the central nervous system. The purpose of the study was to identify the significance of EEG in the prognosis of treated children and pinpoint to what extent EEG readings can predict patient progress in future time.
The subjects were 68 children who had been previously diagnosed with West Syndrome. All patients received a preliminary EEG to confirm the presence of hypsarrhythmia, the characteristic EEG pattern in West Syndrome. They took control EEGs of the participants at the start of the study, 3 months, 6 months, one year, and two years (Nikolic et al., 2018). These readings were then compared to each other, where improvement, unchanged, or worsened EEG readings were noted. Further, these results were compared to the therapy protocols for West Syndrome, wherein improved EEG readings and a decrease in seizures marked a good response to therapy, unchanged EEG and incomplete seizure control meant a slight response to therapy, and poor response to therapy and a worsened EEG meant that the patient would likely have worse EEG responses in the future (Nikolic et al., 2018).
The most significant finding was that there was a clear correlation between the outcome of patient EEG scans and the patient’s improvement in seizure control after six months (Nikolic et al., 2018). This means that patients who showed a marked improvement in the presentation of their hypsarrhythmia at the six month point, paired with therapy, could expect to have seizure control by the two year mark. This usage of EEG scans proves that brain scans, when done incrementally, can be indicative of how a patient will fare in the future at a certain point. The study done used a large sample of children and the correlations proved statistically significant, meaning these results are reliable and can be referenced in the future when studying children with West Syndrome. EEGs are important in noting the current state of a patient, but can also be used to predict their prognosis down the line.
In Vivo Electrophysiology in Animals or Humans
In vivo electrophysiology is an intricate test used to measure the electrical charges that come off of neurons in the brain through microelectrodes. Specifically, “in vivo,” means “in the living,” which means that these tests are done to animals or humans that have been anaesthetized in order to study the workings of live brain cells. In in vivo electrophysiology, the unconscious animal is placed in an instrument that allows a microelectrode tip to be slowly lowered into the brain until it makes gentle contact with a desired neuron without damaging it by being placed immediately adjacent to the cell. Once the tip is in contact, action potentials within the neuron are detected and measured in small voltages, allowing scientists to understand the messages that flow between neurons and what their purposes are within a neuronal network or brain system (Aston-Jones & Siggins, 2000).
In vivo electrophysiology is used for a number of reasons in research. One type of technique, iontophoresis, helps researchers understand the immediate effects a drug has on a particular neuron by releasing neurotransmitters onto the cell. This helps to understand which neurotransmitters are naturally released by a neuron through applying a neurotransmitter exogenously, as well as learn if a drug could have confounding effects within the context of the neurotransmitters already released by the neuron. Secondly, in vivo electrophysiology can be used to study the intercellular communication between neurons by stimulating and afferent neuron and recording the voltage effects on the receiving cell. This can be done before and after a drug is introduced to study its effects on the cell. Another type of reason for the research, called antidromic activation, confirms if one neuron interacts with another, and the amount of time it takes for an electrical charge to be communicated between the two of them (Aston-Jones & Siggins, 2000).
There are a number of advantages and disadvantages for the use of in vivo electrophysiology. The clear advantage, particularly over in vitro electrophysiology, is that the brain cells studied are intact and active within their natural neuronal systems. All of the hormones and chemicals are alive and playing their role in the brain while the research is being done, so researchers can study the effects of drug neurotransmitters or the communication between neurons in their natural context, which leads to more reliable and relevant knowledge of what drugs may work well within the brain in specific synapses and what will not. Disadvantages include the fact that these kinds of studies are difficult in nature to carry out. Further, despite the fact that the brain is live and provides a natural context, there may be confounding effects of either the anesthesia the organism is placed under, or the stress of the immobilization required to carry out these tests (Aston-Jones & Siggins, 2000).
Nicol, Perentos, Martins, and Morton (2016) developed a method of measuring the biomechanics involved in rumination in sheep. Sheep spend most of their time ruminating their food, which is the process by which they chew, swallow, and then spit up bile and part of what they ate in order to break it down to satisfaction for their body to process. This process is innate to them and requires a complex motor system in order for cud to be chewed fully. These sheep were studied to make a comparison between sheep with abnormal neurological processes that disrupt their ability to masticate effectively, and humans with neurodegenerative diseases that disrupt their day to day functions as well. The researchers sought to find markers of these progressions to help treat humans with diseases such as Huntington’s disease (Nicol et al., 2016).
The study used 10 sheep, two of which were neurologically impaired, with one having damage to a facial nerve. The other impaired sheep was purposefully given Ovine Batten disease, which exhibits symptoms such as blindness and decreased motor control. Since the sheep were live, all neurons studied were measured with electrophysiological readings. All sheep were anesthetized and implanted with EEG, EOG, and EMG electrodes, as well had their electrophysiological readings taken. After implantation and recovery, the sheep were fitted with ambulatory amplifier devices and instrumentation jackets to easily hold all recording equipment. They were observed in their own pens within view of the other sheep and readings were taken every 24 hours to record the neurological processes involved in mastication and rumination. Most of the sheep were observed for up to 155 days, however, the sheep with the Ovine Batten disease was observed for 461 days to allow time for disease symptoms to set in (Nicol et al., 2016).
The normal sheep, on average, were found to ruminate anywhere from 20 minutes to 45 minutes each hour, which when paired with the recordings, found that neuronal signals related to the head and neck detected and influenced ruminating and eating in the sheep. Their use of electrophysiology helped them to monitor the electrical signals that caused the sheep to exhibit their eating behaviors. They found that these systems were disrupted in the neurologically abnormal sheep, who displayed shorter spans of these behaviors because of either nerve damage to the muscles in the face, or the disease that attacked the normal input and output of signals in their neurons. The system they developed and the findings related to the subjects’ head and neck signals may lead researchers to be able to monitor these systems and symptoms in humans in the future, without the need for invasive surgery. The research, while sound, could have benefited from a more in-depth analysis of the data obtained and how it can benefit humans with neurological diseases in the future (Nicol et al., 2016).
In vitro electrophysiology seeks to study drug actions and the voltage communications within neurons and through their ion channels, however, the in vitro process of obtaining this information uses samples of neurons that have been taken from deceased brains, isolated and prepared outside of its living context in the organism. In the patch clamp technique, a pipette is lowered to the neuron, and a small amount of suction pulls the membrane wall containing the ion channel into the pipette, creating a tight gigohm seal and allowing the pipette access to the inside of the cell. This allows researchers to measure the electrical currents flowing through the neuron, as well as directly insert neurotransmitters or a drug into the cell. There are multiple ways to use the patch clamp technique, including the cell-attached method, where the pipette remains attached to measure the cell’s electrical activity without disrupting the membrane, the inside-out method, where the patch is pulled away to expose the cell’s interior to the solution in the culture, and the outside-out method, where the pipette pulls the cell membrane and exposes the cytoplasmic membrane to the solution (Aston-Jones & Siggins, 2000).
The patch clamp technique, developed in the 1970s, helped scientists discover ion channels and their currents. This discovery led to our understanding of how action potentials work through ions passing across the cellular membrane to create the charges that allow our neurons to communicate. Today, in research, the patch clamp technique can be used in a large array of studies to understand the ions that are involved in helping a single neuron carry out its processes. The cells commonly studied with the patch clamp include neurons, oocytes, muscle fibers, and cardiomyocytes. This means that the patch clamp technique helps researchers understand how the ion channels in many parts of our bodies function in states of health and states of disease, and drugs can do to help (Molecular Devices, 2018).
The in vitro electrophysiology patch clamp technique has many benefits. Because the samples are taken from the organism and prepared in a culture or bath by the researchers, their environment is fully up to the control of the researcher and there are no confounding interactions from hormones and other synapses one would find in the neuron’s natural state. Further, since the cell is in the full control of the researcher, there are infinite possibilities for the chemicals and drugs that can be applied to the cell tests that can be run to determine the influence variables have on the cell. Researchers can manipulate the molecules involved in the cells processes and study the direct results of drug action without fear of disrupting the natural anatomy of a live organism. However, because these cells are isolated from the brain, their function is not fully reflective of what would naturally occur in a neuron that is in communication with other neurons. Due to the lack of hormones, steroids, and countless other molecules that interact with neurons to create their functions, it is sometimes difficult to provide natural, “real world” analysis of what would occur in a living thing should the research done on the isolated cell be applied (Aston-Jones & Siggins, 2000).
Zhou et al. (2017) researched ion channels that play a role in the presentation of kidney disease in humans through rat models. Kidney disease is usually caused by focal segmental glomerulosclerosis (FSGS) in humans, and can be diagnosed by proteinuria and scarring of the glomerulus. This scarring, caused by podocyte remodeling, is caused by gene mutations that lead to an increase in Rac1 cause an influx of calcium in ion channels that leads to the podocyte cytoskeletal remodeling Presently, treatments do not exist to halt the progression of the disease. Because of this lack of preventative treatment, the researchers sought to study if inhibition of this pathway through ion channel research could provide new insights into how to treat and prevent kidney disease in humans (Zhou et al., 2017).
The researchers used rats with FSGS who displayed severe proteinuria to study the effects of podocyte degradation in FSGS. After the rats died, researchers isolated rat glomeruli and used the patch clamp technique to measure the amount of influx of calcium in the presence of angiotensin II. The electrophysiological reading displayed that the calcium influx in podocytes, mediated by the presence of TRPC5 (ion channels activated by Rac1), was correlated with FSGS progression. After this, they were able to identify a molecule, AC903, that blocks the the ion activity created by TRPC5, through research on live rats who have proteinuria (Zhou et al., 2017).
The present research was able to identify a molecule that blocks TRPC5 activity, which causes an influx of calcium in the glomeruli of rats and triggers kidney disease. This research is significant because this could help develop medicines in the future that prevent the development of kidney disease in humans. The patch clamp technique was used to isolate glomeruli from afflicted rats and study the ion channels’ activity, thus lending an idea as to what molecules may be able to block the chain of events that lead to FSGS, and thus kidney disease. The research seemed sound and reliable, however, there was information lacking, such as how many rats they used in their research. More elaboration as the the methods used specifically may lend itself to the readers’ understanding of what was done (Zhou et al., 2017).
Optogenetic techniques
Optogenetics is a form of research that uses the way neurons communicate with each other to pinpoint exactly what neurons control what behavior or disease in the brain. It can control neurons in the brain through light and genetic engineering, meaning that researchers can take an organism’s genetic code, an specify which neurons they want to study by adding a piece of code to it. This extra piece of code is paired with opsins, a protein derived from algae that responds to light. The most popular opsin, channelrhodopsin, responds to blue light, so neurons injected with this type of opsin will be “turned on” when activated with a blue light. Because of this, researchers can activate specific neurons to study what their effects are (Lim & LeDue, 2017). The neural cells can either be activated or blocked, thus creating or inhibiting many different (but specific) effects in specific muscles (Ives, 2018).
Optogenetics can be used in research to solve many questions about the brain. Because it helps create a functional map of the brain’s neurons, scientists can begin to understand which neurons interact with each other to produce specific effects. Recently, scientists have begun to use optogenetics to study the effects of strokes in mice. Optogenetics were used to create a functional map of the brain of a mouse who had suffered a stroke and compared it at different time intervals to a healthy mouse. They had found that a stroke in a specific area of the brain can stunt the activity in other regions, even those regions far away from the initial region (Lim & LeDue, 2017). Optogenetics can also be used to develop medications. Medications can block neurotransmitters to prevent a certain pain or improve a sensation, but these different molecules can be found all over the brain and in more places than necessary to create the desired effect. What optogenetics can do to resolve this is pinpoint exactly what neurons will dictate the desired reaction in the individual, and help researchers and scientists create medications that are more specific to the brain regions that will produce the effect, without interrupting the actions of the other cells that may otherwise be targeted with a general medication.
There are upsides and downsides to the use of optogenetics. The positive is that it is a burgeoning and promising area of research that, in the future, may cause us to be able to “flip the switch” and turn off the genetic code and neural activity responsible for diseases such as depression. This would be a monumental advancement and have incredible effects on how the scientific community approaches diseases and their treatment. The downside is that, up until now, there have been no significant clinical trials of optogenetics in humans. Most research, thus far, has been in animals. Groups have started to make plans for clinical trials, however, these would require subjects to submit to an invasive procedure that would require an optic fiber be imbedded into their brain (Sutherland, 2016). That being said, there are great hurdles to be overcome before optogenetics can become a routine procedure to improve human quality of life.
Abe and Yawo (2017) sought to study the role of optogenetics in rats’ somatosensory inputs for their whiskers to learn about what specific brain mechanisms lead them to act on conditioned behaviors. When organisms come into contact with a sensory stimulus, whether it be touch, smell, or otherwise, parts of the brain in charge of that somatosensory region react and generate action potentials to allow the organism to determine what part of their body was touched, or what the source of the stimulus was. Rats’ whiskers gather information that is sent to their primary somatosensory cortex to determine position, size, shape, and texture of objects (Abe & Yawo, 2017). Because of the acute ability of rats to use their whiskers, the study sought to use optogenetics to innervate their mechanoreceptors and influence the level to which they licked a sugar reward in response to a behavioral conditioning test.
The study used a minimum amount of rats. The rats were housed with access to food and water and were kept on a twelve hour light/dark cycle. The rats had surgery to implant a steel plate into their heads, and after recovery time, their whiskers were activated with nine optical fibers that was placed in the region of their brain housing the neurons that activate nine whiskers. The other end of the optical fibers was attached to an LED light source. The rats were conditioned with a task, in which the blue light cue of the optical fiber would indicate that the rat should lick the nozzle within five seconds. If they accomplished this, they would receive a reward of water with saccharin. The rats who received the light cue were compared to rats who did not receive the light cue. They were then conditioned in a task where they were not allowed to lick until the reward was presented (Abe & Yawo, 2017). Their responses were made in comparison to other rats that were purposefully blinded, rats that received surgery in other areas of the brain, and rats that had no surgery at all.
The study found that rats were successfully conditioned to respond to the blue light activation of their neurons in control of their whiskers, with an increase in their successful licking after the blue light indicated they should lick, as indicated in Figure 2H (Abe & Yawo, 2017). This study was able to track how quickly the action potential was created in the rats’ neurons and how fast that led to their lick, with rats experiencing the action potential within 1-10 ms of the optical current being activated (Abe & Yawo, 2017). This research is important because it combines behavioral conditioning with optogenetics in order to discover how effectively the brain regions of rats can be irradiated in order to produce desired effects. They found that using optogenetics to dictate action potentials in the rat’s brains could cause them to have greater responding to conditioning.
Transgenic Animals: KO Animals
Transgenics is exactly what it sounds like. It is when a gene is purposefully placed in an animal, usually mice, to induce a disease or ailment similar of that found in humans to study its origins and effects. A transgene is injected inside the genome of a fertilized egg cell and implanted into a female who will then give birth to pups who carry the gene that causes the disease that is wished to be studied. Similarly, knockout mice undergo similar gene mutation, except in their case, a gene is manipulated within their natural genetic makeup and replaced with an inactive gene. There are two ways researchers can do this. They either use homologous recombination, in which they manipulate the gene by introducing an artificial set of genes that overrides the natural and is swaps in the DNA with the artificial, or gene trapping, which is less specific to a particular gene. In gene trapping, the artificial genes are randomly inserted into DNA sequence genetically alters the mouse’s genes. The mice with the knockout allele are then bred, allowing researchers to study the effects of that gene through seeing the difference in their phenotypic makeup or behavior (National Human Genome Research Institute, 2014).
Because mice and humans share similar genetic makeup, knocking out genes in mice can allow researchers to study what genes either contribute to or cause diseases that are seen in humans. These diseases can include cancer, diabetes, anxiety, Parkinson’s, the effects of aging, to name a few. This gives researchers a basis on which to develop drugs and treatments that could aid humans suffering from these ailments, since this type of genetic manipulation in humans would be unethical (National Human Genome Research Institute, 2014).
There are some positives and negatives of using knockout mice in research. There is a benefit in that it allows us to research diseases on a genetic level in a way that would not be allowed in testing done on humans. Because the genetics of the animals are manipulated to mimic or study the effects of particular genes on diseases and behavior, the animals’ quality of life is almost certainly threatened, which would not be ethical to do in humans. Because of this, however, we can develop medications that help humans who do suffer from specific conditions. Similarly, however, because the quality of life is threatened in the animals, there is a 15% chance that the knockout mice will not grow to be adults due to their altered genetics, which limits the amount of animals that can be studied, and also makes it more difficult to apply findings to adult humans since their genetics are different from the genetics of embryos (National Human Genome Research Institute, 2014).
Fragile X syndrome is a disease found in humans characterized by dysmorphic facial features, social anxiety, autistic-like behavior, and sometimes seizures. Sabonov et al. (2016) used knockout mice to study the role of GABAergic inhibition in their hippocampus and see if therapies in humans with Fragile X would benefit from intervention of GABAergic inhibition. Fragile X, with its impaired GABAergic signaling lead to a disruption of inhibition and excitation in neurons, which impairs their ability to function normally and healthily. Fragile X can be modeled in mice by breeding the mice to lack the Fmr1 protein. They sought to study the consequences of this Fmr1 deletion on GABA receptor inhibition and what this would mean for humans suffering from Fragile X (Sabonov et al., 2016).
The subjects used were 29 male wild-type mice and 28 male Fmr1 knockout mice who were kept in 12 hour light/dark cycles in standard mouse cages under common laboratory conditions with food available whenever they wanted it. The 28 knockout mice were specifically bred to have the Fmr1 mutation, thus mimicking the effects of Fragile X in humans. Researchers took transverse slices of all subjects’ hippocampuses and studied the neurons for an evaluation of their ability to sense and respond to varying levels of stimuli, their presynaptic effects through paired-pulse stimulation, and studied their synaptic fatigue and recovery. Through whole-cell voltage clamp recordings, they were able to ascertain the level of stimulus the knockout mice neurons would respond to as compared to the neurons in the wild-mice, and how GABAergic inhibition influenced the neuron’s capabilities of proper functioning (Sabonov et al., 2016).
The research found that Fmr1 knockout mice had damaged hippocampuses, which paired with GABAergic mediated inhibition, caused a lack of appropriate response in neurons to stimuli. This means that therapy for humans with Fragile X should be mindful of the effects of GABA inhibition and seek to improve these effects in humans. According to the research, the Fmr1 knockout mice had a lower capability to respond to alpha GABA levels of stimulation and beta GABA levels of stimulation, as well as had lower responses to IPSC stimuli. These results are significant because Fmr1 knockout mice share similar genetic mutations to that of humans with Fragile X, therefore, this data can be reasonably expected to apply those who suffer from it. The research confirmed the assumption that Fmr1 and Fragile X inhibit GABA receptor abilities and damage the neuron’s capacity or excitation and inhibition (Sabonov et al., 2016).
Transcranial Magnetic Stimulation
Transcranial magnetic stimulation is a procedure used to treat and improve the symptoms of depression. It is noninvasive but is only typically used when all other treatment plans prove unsuccessful in a patient. While depression is treatable, the common methods of treatment sometimes do not work. This can lead patients to turn to transcranial magnetic stimulation, which has been shown to improve mood and reduce the symptoms of depression. Around 55% of patients have a good response to it, with 30% having a complete recovery from symptoms (Harvard Health Publishing, 2018). Before a procedure, patients are asked to remove any magnetic jewelry, as that could disrupt the function of the magnetic transmissions and wear earplugs to protect their ears from the clicking that the machine makes. Also, prior to treatment, patients are given a physical examination and a psychiatric exam to discuss the patient’s depressive episodes and symptoms. During a transcranial stimulation treatment, practitioners place electromagnetic coils against the patient’s scalp. This serves to stimulate neurons through electric currents in regions of the brain involved in depression and low moods and improve their activity (Mennito, 2018).
Transcranial magnetic stimulation can not only be used to treat depression in individuals, it can also be used to research a number of conditions such as multiple sclerosis, movement disorders, and evaluate damage from stroke. It does this through analyzing the connections from a muscle to the primary motor cortex. There are many benefits, but also some risks to having a transcranial magnetic stimulation treatment. TMS is considered safe and is non-invasive, but the risks headaches, discomfort at the site of stimulation, spasms or tingling in the facial muscles, and lightheadedness. However, in rare cases, the treatment could be linked to seizures, mania, and hearing loss if earplugs are not worn during treatment (Mayo Clinic, 2018).