Biopsychology Final PDF

a) Discuss the role of the hippocampus and striatum in the different types of memory The part of the brain called the Locus Coeruleus increases the release of epinephrine throughout the cortex, releasing dopamine into the hippocampus. Emotion causes the release of epinephrine and cortisol, activati...

a) Discuss the role of the hippocampus and striatum in the different types of memory The part of the brain called the Locus Coeruleus increases the release of epinephrine throughout the cortex, releasing dopamine into the hippocampus. Emotion causes the release of epinephrine and cortisol, activating the amygdala and the hippocampus, enhancing the consolidation of recent experiences. The role of the hippocampus is vital for memory in humans. A significant case study in psychology on a person called H.M. highlights the hippocampus’ importance and role. In this case, the hippocampus, and nearby structures of the medial temporal cortex from both hemispheres were removed to prevent epileptic seizures. After the removal of the hippocampus, his seizures almost stopped, and intellect, personality, and language abilities remained about the same, besides some emotional placidity. However, H.M. was left with serious memory impairments such as anterograde amnesia and retrograde amnesia. Anterograde amnesia is the loss of ability to form new memories after brain damage, while retrograde amnesia is the loss of memory from events prior to brain damage, especially from 1 to 3 years before. Interestingly, H.M.’s short term or working memory, the ability to hold and manipulate information in the mind over short periods of time, remained intact. He was able to remember a number after about 15 minutes without distraction, but when distracted, the memory was gone within seconds. His storage of long-term memory was very impaired, and he had great difficulty forming new long-term memories. For instance, he was unable to state the correct date or his current age, he read the same magazine repeatedly without losing interest, could only recall a few events from the recent past, could not even recognize himself in a photo and only in a mirror, and failed to learn the meaning of new words that entered the English language. Overall, this case study with H.M. suggested that the hippocampus is necessary for the formation of new long-term memories. H.M. had severe loss of episodic memory in contrast to his semantic memory. He was able to form only a few weak semantic memories which are memories of factual information but had severely impaired episodic memory so he could describe only a few personal memories. Severe loss of episodic memory meant that he could describe facts from before his operation but only a few personal experiences. Memory loss even affected his ability to imagine the future because describing past events and imagining future ones activate the same brain areas, according to fMRI scans, including the hippocampus. Therefore, people with an inability to have episodic memories cannot imagine the future. The hippocampus relates most strongly to episodic memories which always include context and act as a coordinator, tying together representations from various cortical areas. When people retrieve an episodic memory, activity in and around the hippocampus synchronizes with several cortical areas. Additionally, when the hippocampus is damaged, people tend to be less flexible when learning a new skill and then being able to switch to the old one. Another patient, not H.M., was tested with three nurses. One of the nurses was friendly, one neutral, and one stern. He preferred the friendly nurse but was unable to say why. The patient, K.C., was an amnesia patient who suffered from hippocampus damage causing him to have better implicit than explicit memory. Explicit memory, also known as declarative memory, is the deliberate recall of information that one recognizes as a memory. Implicit memory is the influence of experience of behavior even if one does not recognize that influence. Still, H.M. and K.C. are both examples of amnesia patients that have intact procedural memory. For example, H.M. learned to read words written backwards and K.C. learned to use the Dewey decimal system to sort books and is employed part-time at the library. Both patients tended to be less flexible when learning a new skill and then being able to switch to the old one when experiencing damage to the hippocampus. In conclusion, both patients experienced similar damage that resulted in normal working memory, unless distracted, severe anterograde amnesia for declarative memory causing difficulty forming new declarative memories, and severe loss of episodic memories, better implicit than explicit memory, and intact or nearly intact procedural memory. Delving further on the topic of declarative memory, it can be tested by a delayed matching-to-sample task in animals. In this procedure, animals see an object and after a delay get to choose between two objects, one of which matches the sample. There is also the delayed nonmatching task which is the same except that the animal chooses a different object than it is originally shown. Memory representations develop in parallel in the hippocampus and cortex from the start. The hippocampus stores details while the cortex stores semantic information. As time passes, the hippocampal representation weakens while the cortical representation remains. While declarative and especially episodic memory are dependent on the hippocampus, the striatum is responsible for learning habits or learning what will or will not likely happen under a set of circumstances. The striatum is part of the basal ganglia and orients behaviors relative to your body, but the hippocampus orients behaviors toward external landmarks. Two possible reasons why habits are learned gradually but are not easily forgotten is that they are practiced frequently and do not depend on the hippocampus where new neurons are formed. Also, probabilistic learning depends on the striatum. For example, there are multiple strategies for guessing yes or no with different probabilities of being correct and with more trials you would likely get more accurate with answering this question even though you can’t describe how. Finally, research has shown that there is a division of labor between the striatum and other brain areas including the hippocampus and the cerebral cortex, though it takes both systems for most tasks. Therefore, hippocampal learning is at the beginning of a task since it is mostly declarative, but once it becomes habitual, the striatum plays a bigger role. The striatum is important for habits and implicit memories, often hard to express in words. The speed of learning is slow and gradual, and the way of orienting behaviors is relative to the body. For probabilistic information, it gradually learns to weigh many types of information. It is slow to change and difficult to inhibit, and if the striatum is damaged, there is impaired learning of skills and habits. Episodic memories depend on an exchange of information between the hippocampus and the cortex. To reactivate a memory, the hippocampus and cerebral cortex bounce messages back and forth with sharp wave-like ripples. The ripples serve to re-experience a past event and the ripples lasted longer when people took longer to recall older events, suggesting that the ripples represent efforts to recall something. Studies found that the ripple patterns during memory recall often resemble those that occurred during original learning. b) Discuss the different functions of each hemisphere in relation to emotions, language, and different senses. Describe the visual and auditory connections to the hemispheres, the results of split-brain surgery. The human brain is asymmetrical and divided into the left and right hemisphere, each having different functions. Each hemisphere controls the opposite side of the body, with some exceptions like the smell from our own nostril is tied to the same hemisphere and taste from both sides of the tongue. The division of labor between the two hemispheres is known as lateralization. Information is exchanged between hemispheres through the corpus callosum, the anterior commissure, the hippocampal commissure, and a few other small commissures. The left hemisphere connects to skin receptors and muscles on the right side of the body and vice versa, the exception being both control of the trunk and facial muscles. The corpus callosum allows each hemisphere of the brain access to information from both sides. One section of the temporal cortex, planum temporale, is larger in the left side for 65 percent of people. The difference is even seen in infants. Young children activate the right hemisphere during speech more than adults do and as they grow older, most of them gradually suppress the right hemisphere during speech and emphasize the left hemisphere. Each hemisphere of the brain gets input from the opposite half of the visual world. For instance, light from the right half of the visual field shines into the left half of both retinas and light from the left half of the visual field shines onto the right half of both retinas. Also, the left half of each retina connects to the left hemisphere so sees the right visual field and the right half of each retina connects to the right hemisphere so sees the left visual field. Half of the axons from each eye cross to the opposite side of the brain at the optic chiasm. Though the auditory system is arranged differently in that each ear sends input to both sides of the brain and the brain areas must compare input from both ears, each hemisphere does pay more attention to the ear on the opposite side. Damage to the corpus callosum prevents the hemispheres from exchanging information. For example, in epilepsy patients, if they do not respond to anri-epileptic drugs, doctors will attempt to remove the focus. Removing the focus is not an option if there are multiple foci or if the focus is essential for language. Other surgical options include cutting the corpus callosum which restricts the seizure to one hemisphere. A surprising bonus was that the seizures became less frequent. Epileptic activity rebounds back and forth between the hemispheres and prolongs a seizure. Split-brain people have undergone surgery to the corpus callosum, yet they maintain normal intellect and medication, still able to walk and talk. However, it’s hard for them to use their hands together on tasks they had not previously practiced and can describe something they feel with their right hand but not their left. But they can use their hands independently in ways other people cannot like drawing different things simultaneously with each hand or moving their hands at different speeds. At the same time, Sperry 1974 revealed behavioral differences for split brain people when stimuli were limited to one side of the body. Because the left side of the brain is dominant for language in most people, most split brain people have difficulty naming objects briefly viewed in the left visual field. A small amount of information can still be transferred via several commissures. Because of the slow development of the corpus callosum, behaviors of young children occasionally resemble those of split brain adults. Their ability to compare what they feel for both hands increases from 3 to 5 years old. Immediately after surgery, the brain hemispheres are often in conflict. Conflicts become rare as time passes and the brain learns to use smaller connections. The hemispheres show differences of opinion if tested carefully enough. Gazzaniga in 2000 proposed the concept of the left brain as the interpreter. It has the tendency to invent and defend explanations for actions, even when the true cases are unconscious, which is not limited to people with split brain operations. In most humans, the left side is specialized for language and speech. For instance, brain surgery patients with the left hemisphere inactivated cannot speak. Also, studies show that those who begin learning a second language after the age of six show only activity on the left hemisphere. Visual word form is usually controlled on the left hemisphere, while facial recognition is usually on the right hemisphere. When the right hemisphere is inactivated, they can describe traumatic or emotional experiences but do not remember feeling the emotion. This is true for about 95 percent of right-handers and 80 percent of left-handers. For the right hemisphere, the functions are more difficult to summarize. The right hemisphere is better at comprehending spatial relationships, helping see the bigger picture and relating what one hears to the overall context. Those with left hemisphere damage distinguish better honesty from dishonesty in speech because they so not rely on words but intuition. The right hemisphere of the brain Is also related to depressed mood. Damage to the right hemisphere causes difficulty finding one’s way, perceiving others’ emotions, and being able to have a non-monotone voice. ­ c. Explain the role of emotions from a biological standpoint Emotion situations arouse the autonomic nervous system. Most situations evoke a combination of sympathetic and parasympathetic arousal which are two parts of the autonomic nervous system, e.g. stimulating the heart while inhibiting the stomach and intestines. Also, another example is if a little animal may become alert at the sight of the predator and become motionless with a decreased heart rate (parasympathetic being activated) but if predator approaches the sympathetic become activated. Is physiological arousal necessary for emotion? Pure autonomic failure is when the autonomic nervous system ceases activity. In this case, organs continue to function but without regulation by the nervous system, their organs do not have the physiological reactions to experiences. People with this condition report feeling same emotions, but less intensely. They are mostly aware of the cognitive part of the experience. People with damage to the right somatosensory cortex have typical autonomic responses to emotions but report little subjective experiences. On the other hand, people with damage to part of the prefrontal cortex have weak autonomic responses but normal subjective responses. These two results suggest that autonomic responses and subjective experience are not always closely connected emotional feelings to be intense; autonomic responses are necessary. Also, people with BOTOX injections who find it difficult to frown, report less depression, implying that body change is important part of feeling an emotion. From a biological standpoint, much evidence favors the idea of emotional experiences in continuous dimensions. For instance, heart rate and breathing rate increases with the intensity of an emotion. They do not distinguish between fear and anger or any other pair of emotions. You could not simply identify anyone’s emotion by measuring autonomic activity. The limbic system includes the forebrain areas surrounding the thalamus, traditionally regarded as critical for emotion. Much of the cerebral cortex also reacts to emotional situations. For instance PET and fMRI studies suggest particular cortical areas are activated during an emotional experience. The only emotion that seems to depend mostly on one brain area is disgust which is also linked to the insula, an area related to taste. Researchers have found strong responses in the right hemisphere junction between the temporal and parietal cortices while people watched an emotionally charged movie. There are three gradients of emotional response- pleasure vs displeasure, intensity, and complexity of emotions. These findings support the idea that brain responses are well described as dimensions of emotion rather than as discrete categories. There are also hemispheric differences and activation vs inhibition in the right and left hemisphere. The behavioral activation system (BAS) is in the left hemisphere and the behavioral inhibition system (BIS) is in the right hemisphere. On average, people with greater activity in the frontal and temporal cortex of the left hemisphere (BAS) tend to be happier and more extroverted, while people with greater right-hemisphere activity in the frontal and temporal lobe (BIS) tend to be more socially withdrawn, cautious, and prone to unpleasant emotions. Overall, the right hemisphere is more active in perceiving emotions, such as negative emotions such as fear. The main support for the idea of basic emotions has mostly relied on consistency of facial expressions. People around the world have similar expressions for similar situations. For instance, people who have been blind since birth exhibit expressions of happiness, sadness, fear, pride, and shame that resemble those of sighted people. Therefore, emotions are built into our biology, though there are some modifications in expression that take place. However, research has proven that people recognize expressions from their own culture better than those from other cultures. We rarely just use facial expression alone to identify people’s emotions, we also use posture, for instance. d. What is the function of emotions? Why does the usual way of testing recognition of emotions overestimate accuracy? If we evolved the capacity to experience and express emotions, emotions must serve some adaptive function. Fear alerts us to escape from danger, anger directs us to attack an offender, and disgust tells us to avoid something that might cause illness. The adaptive value of sadness, hipponess, embarrassment, and other emotions is less known. Overall, emotions work as a useful guide when we need to make a quick decision. In moral decision making, we pay much attention to how the outcome will make us feel. COntemplating moral decisions activates the prefrontal cortex and cingulate gyrus. People with strongest autonomic arousal are the least likely to make decisions to kill one person in order to save five others. Moral decisions are seldom made rationally, one decision or the other just “feels” right, then we rationalize after the decision has been made. When you make a moral decision, you compare the utilitarian aspect such as if five people die versus just one person and the emotional aspect like how you would feel after performing the action. fMRI studies indicate that certain brain areas become active when people only contemplate the emotional access and other areas become active when they contemplate just the emotional aspect. The ventromedial part of the prefrontal cortex becomes active when they compare the utilitarian and emotional aspects to make a decision. There are cases where people experience damage to the ventromedial part of the prefrontal cortex and they tend to make decisions without much consideration of the emotional impact. When confronted with moral dilemmas like the trolley experiment, where a person has to choose whether to direct the trolley towards killing one person versus five, they are more likely than the average person to choose the utilitarian option of killing one to save five, even though the option would be to kill a close relative or to kill somebody out of revenge. They may have no sadness or guilt making these decisions. A case like this is the Phineas Gage case by Damasio in 1994 where there was damage to the prefrontal cortex and they had no anger, sadness, or pleasure which leads to bad (not logical) decisions, since decisions also involve emotions and values. The usual procedure to ask people to match six faces to six labels reveals that the usual way of testing emotions overestimates accuracy because after you identify one or more for sure, you improve your chance of guessing the other ones correctly.  e. Discuss the emotional reaction to stress. Explain the levels of stress and its effects. Stress constitutes a major cause of emotions and emotional reactions. For instance, behavioral medicine emphasizes the effects of stressful experiences from diet, smoking, exercise, and other behaviors on health. Emotions and other experiences influence people’s illness and recovery patterns. Hans Seyle (1979) identified stress as the non-specific response of the body to any demand made upon it. General adaptation syndrome is the threat to the body that activates a general response to stress. Stress activates two systems in the body. The first is the parasympathetic nervous system or “flight or flight” response that prepares the body for brief emergency responses. The second is the HPA axis which includes the hypothalamus, pituitary gland, and adrenal cortex. The sympathetic nervous system affects the body by doing things like dilating pupils, accelerating heartbeat, and inhibiting salivation. After the body undergoes prolonged stressors for a longer period of time the HPA Cortex Axis becomes the primary response. It reacts to stress more gradually than the sympathetic nervous system, but its effects continue for longer. Activation of the hypothalamus induces the pituitary gland to secrete adrenocorticotropic hormone (ACTH). ACTH stimulates the adrenal cortex to secrete cortisol. Cortisol helps to mobilize energies to fight a difficult situation. It increases blood glucose, providing the body with extra energy. It also increases alertness and reduces inflammation. There are three stages of the general adaptation syndrome in response to stress. First, the alarm stage increases sympathetic nervous system activity. Then, the resistance stage is when the sympathetic response declines and the adrenal cortex continues release=ing cortisol and other hormones to prolong alertness. The body decreases less urgent activities here like sexual behavior. Finally, the exhaustion stage occurs after prolonged stress, where an individual no longer has energy to sustain stress responses. Sapolsky (1998) argues that the nature of today’s stressors are more prolonged and accounts for widespread stress-related illnesses and psychiatric problems in industrial societies. For Sale, any change in one’s life, either favorable or unfavorable, can be considered stressful. For McEwen (2000), events interpreted as threatening and elicit physiological and behavioral responses can be stressful. Long-term, inescapable issues from life-threatening to matters of brief inconvenience can activate the general adaptation syndrome. As a result, it is exhausting. Stress can impair health by altering people’s behaviors like eating worse, alcohol use, less sleep and exercise, leading to strokes and heart attacks. Though brief and moderate stress can increase energy, performance, memory, activity of the immune system, intense stress negatively affects problem solving, memory and the immune system. Further, the immune system protects the body against viruses and bacteria by producing leukocytes (white blood cells), which include T-cells, B cells and natural killer cells. B cells are leukocytes that mature in the bone marrow and secrete antibodies, Y-shaped proteins that attach to different kinds of antigens, surface proteins on every cell to which the antibodies attach. B cells attack unfamiliar antigens, including viruses and bacteria but also organ transplants a. When the body has ade antibodies, it remembers the intruder and quickly creates more of these antibodies and it meets the intruder again. T cells mature in the thymus gland and attack intruders directly and help other T-cells or B-cells to multiply. Lastly, natural killer cells are leukocytes that attack tumor cells and cells infected with viruses. They attack all intruders. If the immune system is too weak, the viruses and bacteria will intrude the organism, if though too strong, it will attack itself causing autoimmune diseases like myasthenia gravis and rheumatoid arthritis. During an infection, leukocytes and other cells produce small proteins called cytokines. Cytokines combat infection and communicate with the brain to inform of illness. Cytokines stimulate the release of prostaglandins. Prostaglandins produce fever, sleepiness, lack of energy, lack of appetite and loss of sex drive. Sleep and inactivity conserve energy to fight illness, save ener=gy for the immune system to attack the intruders. Also loss of appetite leads to decreased glucose which is the fuel for microorganisms.Psychoneuroimmunology deals with the way experiences alter the immune system and also examines how the immune system influences the central nervous system. In response to a stressful experience, the nervous system activates the immune system. It increases production of natural killer cells, leukocytes, and cytokines. The cytokines combat infections, but also trigger prostaglandins which reach the hypothalamus, where they produce the same effects as illness-sleepiness, decreased appetite, and elevated body temperature. If stressed and experiencing symptoms of illness, it is possible that the symptoms are in response to stress. Natural experiments done by Tingate et al in 1997, follow a 9 month period of cold, darkness, and social isolation in Antarctica which reduced T cells to about a half. A field experiment done by Cohen in 2021 where participants were exposed to viruses and those under chronic stress were more likely to express symptoms of illness. Also, prolonged stress produces symptoms similar to depression, weakens the immune system, and can harm the hippocampus (by cortisol) leading to worsening memory. When you experience stress, you may also experience signs of digestive upset. Enteric nervous system, a set of neurons that control digestion are activated by the brain and stress hormones. The effect of stress could be seen on how the digestive system will respond. Some of its bacteria may produce IBS and visceral pain and some of its chemicals may increase the risk of anxiety and depression. Overall, people’s response to stress varies. What determines resilience our ability to recover well from a traumatic experience has to do with genes, social support, optimistic view, reappraisal of difficult situations, physical health, and previous stressful experiences like it it was successfully dealt with moderately in the past it may be useless or serious adverse effects may cause exhaustion. There are methods to control stress responses like breathing routines, exercise, meditation, distraction, and addressing issues. Social support from a loved one also helps to reduce stress. Reduced response to painful shocks in several brain areas including the prefrontal cortex occurred when women were holding their husband’s hand (Coan, et al., 2006). Natural experiments with information before and after starting a military service provide significant results on resilience based on research by Ursano et. al. in 2020. f. Explain why Lashley’s search for the engram of memory failed and why a later attempt succeeded. Engram proposed a physical representation of what had been learned. For example, a connection between two brain areas. The hypothesis is that a knife cut between the two brain areas should abolish the newly learned response. This hypothesis was disproved through his experiment with rats. He trained rats on mazes and brightness discrimination tasks and then made cuts in their cerebral cortices. However, no knife cut significantly impaired a rat’s performance. He also trained rats on the maze before and after he removed portions of the cortex. The lesions impaired performance but the deficit depended more on the amount of brain damage than location. Lashley’s experiments showed that learning and memory do not rely on a single cortical area. Lashley’s principles about the nervous system include equipotentiality where all parts of the cortex contribute equally to complex functioning behaviors and mass action where the cortex works as a whole and more cortex is better. Another interpretation here is that maze learning and visual discrimination learning are complex tasks and different parts of the brain are involves, though not all of them , the same way and level. Lashley’s faulty assumptions are that the cerebral cortex is the best or only place to search for an engram and studying one example of learning is equivalent to studying any other one. Later on, Richard F. Thompson and colleagues suggested that the classical conditioning engram is located on the cerebellum, not the cortex. They studied rabbits using a tone as the CS, puff of air as the ucs, and close of eyes as the ucr. The lateral interpositus nucleus identified as central for learning and responses increase as learning and conditioning proceeded. However, a change in a brain area does not necessarily mean that learning took place in that area. Learning may have taken place in the area before or after LIP. Thomson concluded from experiments in rabbits that learning occurs in the LIF. Later research then identifies cells and neurotransmitters responsible for changes in the LIP. People with damage to the cerebellum exhibit either no conditioned eyeblinks, or only weak, inaccurately timed ones. Damage to the cerebellum impairs a learned response only if the response needs to be made with precise timing. By temporarily deactivating the lateral interpositus nucleus in the cerebellum, all indications of learning became blocked. After inactivation wore off, the rabbits learned as slowly as rabbits with no previous training. Temporarily deactivating the red nucleus blocked responses during the period of inactivation, but the learned response appeared as soon as the red nucleus recovered. Therefore, Thomson found a localized engram while Lashley did not and Thomson studied a different type of learning from Lashley, with a different species and looked at the cerebellum instead of the cerebral cortex like Lashley. g. Distinguish among types of memory and why we forget. For much of the 20th century, most psychologists assumed that all memory was the same. They believe that they could study it simply with any convenient example such as memorizing nonsense syllables. Eventually, psychologists recognized differences among types of memory. For example, Hebb in 1949 differentiated between two types of memory- short term and long term. Short term memory is the memory of events that have just occurred. It has a limited capacity of about 7 items, fades quickly without rehearsal, may be stored through a reverberating circuit of neurons. Long-term memory is the memory of events from times further back. It does not have a limited capacity and memories persist.Researchers propose that all the information enters short-term memory and the brain consolidates it into long-term memory. Later research weakened the distinction between the two because not all rehearsed short term memory becomes long-term memory like where you have parked your car for the day and time is needed for consolidation into long-term varies like if something is boring vs exciting. Emotionally significant memories form quickly. Flashbulb memories work by the Locus Coeruleus increases the release of norepinephrine throughout the cortex and dopamine releases in the hippocampus. Emotion also causes the release of epinephrine and cortisol to activate amygdala and hippocampus enhancing the consolidation of recent experiences. Flashbulb memories are normally when a slight incident is forgotten quickly and when followed by a dramatic incident is remembered together. It can also prevent you from linking events that happen too far apart, such as the next day. Working memory is proposed by Baddeley and Hitch as an alternative to short-term memory. There is more emphasis on temporary storage of information to actively attend to it and work on it for a period of time. A common test for working memory is the delayed response task which requires responding to something you heard or saw a short while ago. During any type of working memory task, a reverberating circuit usually between the cortex and the thalamus, holds the information. Cells holding an item in working memory do not simply repeat the stimulus. If it is just repetition, then the visual cortex would activate the same cells again and again. Instead, the visual system codes a simplified account of just the information needed. We may forget outdated information to replace it with new information. Forgetting the details of an event, helps to focus on the important parts you are interested in. Amnesia can be simply defined as memory loss. Different kinds of brain damage result in different types of amnesia like brain for or Alzheimer’s. Sometimes amnesia is limited to certain aspects of memory like forming new visual memories. Brain fog includes confusion, slow thinking and impaired concentration. Many patients suffered for months after recovery of COVID-19 or from cancer treatments, for example. One hypothesis for this might be that the COVID virus causes a powerful reaction in the immune system that produces inflammatory cytokines which damage the BBB and activate microglia cells that damage neurons and axons. Another hypothesis is that the reaction to the virus impairs the blood flow to the brain. Findings from those who recovered are a shrinkage of gray matter in parts of the cerebral cortex and decreased levels of myelin. h. Discuss the biological basis of Alzheimer’s disease. Evaluate explanations for infantile amnesia. Alzheimer’s disease is associated with a gradually progressive loss of memory, often occurring in old age. It affects 50 percent of people over 85 and 5 percent of people 65-74. People with Alzheimer’s disease are able to learn procedural skills better than facts. It gradually progresses to confusion, depression, apathy, hallucinations, delusions, sleepiness, and loss of appetite. Early onset seems to be influenced by genes and 99 percent of cases are late onset. Type 2 diabetes is also a major risk factor here as well as lack of sleep at a younger age. Genetically speaking, a gene (APOE) found in chromosome 21, in people with Down syndrome or trisomy 21, seems to be related to Alzheimer or cognitive decline in old age. People with Down Syndrome inevitably develop dementia, usually by age 40. No drug is currently effective and there are many side effects, high cost, it focuses mainly on b-amyloidsAl and the damage is already extensive once it is discovered. The brain changes a lot when a person has Alzheimer's disease. For instance, a healthy brain’s cerebral cortex is responsible for language and information processing , but when a person has Alzheimer’s, the cortex shrivels up, damaging areas involved in thinking, planning, and remembering. Again, a healthy brain’s hippocampus is critical to the formation of new memories, but when a person has Alzheimer's, the hippocampus shrinks severely. Also, ventricles filled with cerebrospinal fluid grow larger. Additionally, people experience neuronal degeneration in Alzheimer's disease where there is dendritic spine loss. In detecting AD, the associated brain changes corresponding to it like neurofibrillary tangles and senile plaques appear years before any clinical diagnosis. Neurofibrillary tangles resemble intertwines and twisted pairs of rope within the cytoplasm of swollen cells bodies. These tangles consist of proteins (tau proteins) which have been accumulated, disrupting neurotransmission, damaging mitochondria and triggering microglia to kill neurons. The excessive collection of neurofibrillary tangles creates tangles that are dispersed throughout the brain but disproportionately in the temporoparietal areas and the hippocampal complex. Senile p;aques are “cellular trash” and a certain type of amino acid peptide protein core termed beta-amyloid. These neuritic plaques are also called amyloid plaques. B-amyloid may be related to chromosome 21. The synapses eventually disintegrate, leaving holes and neurites (pieces of axons and dendrites) where there were once active connections. Plaques are likely to concentrate in the frontal and temporal regions and are numerous around the hippocampal formation. Tangles and plaques are not necessarily specific to AD because they may also appear in normally aging individuals without evidence of dementia, as well as in other degenerative diseases. It is the pattern and quantity of these markers that define ADHD may impact multiple neurotransmitter systems. However,the most consistent evidence of a neurotransmitter with a direct affect on memory processes in AD is Ach. Alzheimer’s is denied post mortem by the increased presence of amyloid plaques and neurofibrillary tangles in the brain. Amyloid plaques are extracellular deposits consisting primarily of amyloid-beta peptides and we have already discussed neurofibrillary tangles. On another topic, early childhood amnesia is not a disorder like the previous disease. It is a universal experience that we don’t remember much from our first few years of life. Children do form memories but the question is why they forget them. The hypothesis here is that there are changes in the hippocampus and growth of new neurons, infants do not store memories as well as they can when older, or rapid learning in early childhood displaces memories formed in infancy. i. Describe how the hippocampus and surrounding areas relate to navigation. Define Hebbian synapses. Navigation depends on our surroundings and our special memory. Damage to the hippocampus also impairs abilities on spatial tasks such as radial mazes and Morris water maze tasks. Radial mazes are where a subject must navigate a maze that has eight or more arms with a reinforcement at the end (in that case, may enter the incorrect arm twice, forgetting which ones they have already tried). A rat that reeters one arm before trying another arm has made an error of special working memory. The Morris water maze task where a rat must swim through murky water to find a rest platform just underneath the surface (in that case, they can find the platform only when starting from the same place or if the platform is always in the same location). For instance, 5th trial, the rat never found the platform, 34th trial it did in 35 seconds, and 71st trial found it in 6 seconds. Furthermore, May-Britt Moser, Edvard Moser, and John O’Keefe shared the 2014 Nobel Prize in Physiology or Medicine for their discovery of the cells responsible for spatial memory. Place cells are hippocampal neurons tuned to particular spatial locations, responding best when an animal is in a particular place and looking in a particular direction. When an animal is moving, place cells remap themselves in firing in different shapes and sizes. Place cells also anticipate the next places it will go and again remap themselves when the rat imagines a near future such as being about to move towards a rewarding place. Time cells are some hippocampal place cells that also function as time cells, but respond at a particular point in a sequence of time. They can be active also when the rat pauses, before moving again. Entorhinal cortex cells send information to some hippocampal place cells. Recorded cells in the entorhinal cortex become active at locations separated from one another in a hexagonal grid. Therefore, these cells are called grid cells. At a given level within the entorhinal cortex, different cells respond to different sets of locations, but always in a hexagon. Some cells respond to the animal’s speed of locomotion instead of location or direction. Any episodic memory refers to events that occurred in a particular place, with a particular sequence of events over time. A loss of place cells and time cells of the hippocampus (which finally relate themselves to episodic memory) disrupts many types of memory formation. j. Explain memory and learning. Explain what we learned about memory from studies of Aplysia. Explain the mechanism of long-term potentiation. Evaluate attempted methods of improving memory. Life without memory means no sense of existing across time. Your memory is almost synonymous with your sense of self. Classical conditioning is pioneered by Ivan Pavlov where pairing two stimuli changes the response to one of them. This includes a conditioned stimulus, unconditional stimulus, unconditional response, and conditional response. For example, a ticking metronome (conditioned stimulus) followed by food (unconditioned stimulus) automatically affects salvation (unconditioned response), so after a number of repetition of these events, the ticking metronome (conditioned stimulus) causes salvation (conditioned response) in the dog. This is called classical conditioning where the CS and the UCS occur regardless of the individual’s behavior. Instrumental conditioning also known as operant conditioning is when an individual’s response is followed by a reinforcer or punishment. Reinforcers are events that increase the probability that the response will occur again. Punishment is the event that decreases the probability that the response will occur again. In instrumental conditioning, the individual’s response determines the outcome (reinforcer or punishment). Some cases of learning are hard to label as classical or instrumental. Most of the brain contributes to memory. The amygdala is associated with fear leaning, the parietal lobe associated with piercing information together, including the angular gyrus that is responsible for subjective experience of remembering something. Damage to the anterior temporal complex results in loss of semantic memory, recognizing the meaning of objects, colors, smells, tastes. Semantic dementia varies depending on the location and amount of atrophy. Prefrontal cortex is involved in learned behavior and decision making.  k. Explain how the brain develops including the 5 processes of neuron development, synaptogenesis, focusing on what the brain is like at the beginning of development (vulnerable and fetal alcohol syndrome). Brain development depends upon maturation (homebox genes regulate the expression of other genes and control the start of anatomical development/mutations in one of them may lead to serious mental and physical disorders) and learning. Then, neurons develop (brain basically grows prenatally but also affected by the first years), their axons connect, and experience modified development. The human central nervous system begins to form when the embryo is approximately 2 weeks old. The dorsal surface thickens, forming a neural tube surrounding a fluid-filled cavity. The forward end enlarges and differentiates into the hindbrain, midbrain, and the forebrain. The rest of the neural tube then becomes the spinal cord. The first muscle movements start at 7 and a half weeks, from spontaneous activity in the spinal cord, before sensations become activated. The fluid-filled cavity becomes the central canal of the spinal cord and the four ventricles of the brain, the fluid being the cerebrospinal fluid. In early infancy, the primary sensory areas of the cortex are more mature than the prefrontal cortex. The development of neurons in the brain involves proliferation, migration, differentiation, myelination, and synaptogenesis. Proliferation is the production of new cells.neurons in the brain primarily occurring early in life. Early in development, the cells lining the ventricles divide, some cells stay as stem cells that continue to divide, and others migrate to other locations even for the first few months after birth. Then, migration is the movement of the newly formed neurons and glia to their eventual locations though some do not reach their destinations until adulthood. It occurs in a variety of directions throughout the brain and chemicals known as immunoglobulins and chemokines guide neuron migration. Deficit of these chemicals will lead to impaired migration, decreased brain size and intellectual impairment. Thirdly, differentiation of cells is a process in which stem cells change into more specialized cells. In the case of neurons, it starts by the forming of the axon and dendrites that gives the neuron its distinctive shape. The axon grows first either during migration or once it has reached its target and is followed by the development of the dendrites. Neurons develop different anatomies and functions based on when and where they developed and what genes they express. Next, synaptogenesis is the formation of the synapses between neurons. It occurs throughout life as neurons are constantly forming new connections and discarding old ones, begins long before birth, and slows significantly later in the lifetime. Lastly, myelination is the process by which glia produce the fatty sheath that covers the axons of some neurons. This is a slower stage of neuronal development where myelin speeds up the transmission of neural impulses, first occurring in the spinal cord and then in the hindbrain, midbrain, and forebrain. Myelination continues gradually throughout life. Originally believed that no new neurons were formed in the brain after early development by scientists like Cajal 1800s. For most of the brain, this is correct, though there are exceptions for the olfactory receptors and a few ambivalent results for the hippocampus. This may be measured through the radioactive isotope of carbon C in DNA with the mean C concentration in the DNA of the cortical neurons corresponding to the year of birth. In general, different cells have different average life spans and skin cells change on the average every year and muscle cells every 15 years. Axons must travel great distances across the brain to form the correct connections. For instance, Sperry's 1954 research with newts indicated that the axons follow a chemical trail to reach their appropriate target. Growing axons reach their target area by following a gradient of chemicals in which they are attracted to and repelled by and based on timing of development of neurons and their extensions (those formed earlier extend their axons longer. He ran an experiment when he cut connections to a newts eyes and inverted the eye, axons grew back to their original target. Early stages of brain development are critical for normal development later in life. A mutation in one gene could lead to many defects. Chemicals may cause distortions in the brain, especially during early development, leading to significant impairment and developmental problems. Fetal alcohol syndrome is a condition that children are born with if their mother drinks heavily during pregnancy. It is marked by hyperactivity and impulsiveness, difficulty maintaining attention, varying degrees of mental retardation, motor problems and heart defects, and facial abnormalities. This happens because alcohol interferes with proliferation, migration, differentiation, synaptic transmission. The dendrites of children born with fetal alcohol syndrome are short with a few branches. Exposure to alcohol in the fetus brain suppresses glutamate and enhances the release of GABA. Many neurons consequently receive less excitation and exposure to neurotrophins than usual and undergo apoptosis l. Describe and include examples for the plasticity of the brain (use ferret experiment as example, describe changes of stimuli creating more dendrites and axons, blind adaptations, people without hands using toes)- slides from ferret to having to do with plasticity of the brain Neurons in different parts of the brain differ from one another in their shape and chemical components. Immature neurons transplanted to a developing part of the cortex develop the properties of the new location. On the other hand, neurons transplanted at a later stage of development develop some new properties but retain some old properties. For example, an experiment on ferrets determines if connectivity is enough to determine the function of the region that has these connections. Sharma et. al, 2000 manipulated connectivity in newborn ferrers. They found that if the researchers damage in one hemisphere what would happen? Would parts of the superior colliculi and the occipital cortex which would naturally receive information from the retina be affected or would parts of the auditory input be affected? The result was that the optic nerve attached to the auditory nucleus of the thalamus and produced visual responses by sending to the auditory cortex, visual input. In the ferrets, first the normal (right) hemisphere is trained to respond to a red light by turning to the right. Then the rewired (left) hemisphere is tested with the red light. The fact that the ferret turns to the right indicates that it regards the stimulus as light, not sound. Furthermore, the brain has some ability to reorganize itself in response to experience. Axons and dendrites continue to modify their structure and connections throughout the lifetime and dendrites continually grow new spines. The gain and loss of spines indicate new connections, which relates to learning. Although the central structure of a dendrite becomes stable, by adolescence, it peripheral branches remain flexible throughout lifetime. Another experiment with rats raised in an enriched environment developed a thicker cortex, increased dendritic branching, and improved learning. A simulated environment enhances sprouting of axons and dendrites. Measurable expansion of neurons has also been shown in humans as a function of physical activity. As old neurons die by apoptosis and new ones form to take their place, there is improved memory and learning. The question is how much can we boost intelligence beyond normal by providing special training or greatly enhanced experience? It was once believed that teaching a child difficult concepts would enhance their intelligence in other areas. This concept is known as “far transfer” and actually difficult to be achieved and evidence shows that skills are associated with the practiced task transfer but not to other skills. The brain cannot be exercised like a muscle. On the other hand, generalized training programs to enhance overall intelligence have produced only temporary or modest benefits. Prolonged practice of a particular activity though, produces brain changes that enhance the ability to perform the task. For blind people, the temporal lobe is usually important for visual motion and becomes sensitive to the movement of sound. Blind people, on average, are better at localizing sound and better in detecting tactile information from the finders than sighted people. Blind people improve their attention to touch and sounds, based on practice. Touch information activated the occipital cortex area, which is ordinarily devoted to vision alone. The occipital lobe normally dedicated to processing visual information adapts to also process tactile and verbal information. Further research using magnetic stimulation to inactivate brain areas demonstrated that when inactivation of the occipital cortex occurred, blind people were not able to discriminate between tactile stimuli and Braille symbols, but the feeling of touch was not affected in sighted people. Similarly, with death people, touch and vision activate what would be their auditory cortex. They had increased representation of visual information to enable better recognition of emotional expressions of others. The temporal lobe, where the auditory cortex would be, reorganizes itself and detects peripheral sights well. For people born without hangs, and using their toes to draw or use tools, the sensory cortex developed in such a way to distinguish between toes, since they were used like fingers. Adult experiences may also modify brain anatomy. However, more research is needed to determine whether the effects after brief practice are strong enough to be observed with MRI or similar technology such as studies with juggling. The limitations include finding a result by accident and replications are needed and careful methodology needed. m. the attempts to teach language to nonhumans. How did language evolve? Evaluate the concept of a sensitive period for language development, discussing what is known about bilingualism, and research on dyslexia. Human language is a complex form of communication and compared to other species, human language has high productivity meaning the ability to improvise new combinations of signals to represent new idas. Human language is a modified behavior also found in other species. Chimpanzees use language, but it differs from humans. For instance, they vocalize while breathing in instead of out like humans, seldom use symbols in new original combinations, use of symbols lack productivity and are primarily used to request and not decrines. Bonobos’ social order resembles that of humans such as male and female interactions and relationships. Bonobos Kanzi and Mulika in the 90s found that bonobos understand more than they can produce, use symbols/names to describe objects, request items not seen, use symbols to describe past events, and make original, creative requests. Some possible explanations for Kanzi and Malika’s results are that perhaps bonobos have greater language potential than other chimpanzees, language training began early, and they were allowed to learn through observation and imitation rather than formal training methods used in previous studies. For non-primates like dogs, the left hemisphere responds to meaningful words and the right hemisphere responds to intonation. Researchers have found strong responses in the right hemisphere junction between the temporal and parietal cortices while observing people watching an emotionally charged movie. They discovered three gradients of emotional response being pleasure vs. displeasure, intensity, and complexity of emotions. The right hemisphere is more active in perceiving emotions, especially negative ones like fear. The right hemisphere of the brain is responsible for the behavioral inhibition system (BIS), while the left hemisphere is the behavioral activation system (BAS). On average, people with greater activity in the frontal and temporal cortex of the left hemisphere (BAS) tend to be happier and more extroverted and people with greater right-hemisphere activity in the frontal and temporal lobe (BIS) tend to be more socially withdrawn, cautious, and prone to unpleasant emotions. ­Language may have evolved from communication by gestures, postures, facial expressions. A child's ability to communicate by gestures predicts the onset of spoken language. Sound plus mouth gesture may have been a precursor to spoken language. Brain language theories are that it is a by-product of overall brain development and evolved as a specialization. People with a full-size brain and normal overall intelligence can show severe language deficits. In a family, 16 people over three generations have a dominant gene that impairs their language but have “normal” intelligence. On the other hand, people with impaired intelligence have normal language skills. People with Williams syndrome have the possibility of developing better language abilities than other intellect implies that language is more than just a by-product of overall intelligence and actually developed through evolution as a specialization. Shomsky (1980) and Pinker (1994) proposed that humans have a language acquisition device that is basically a built in mechanism for acquiring language. Evidence comes from the ease at which most children develop language. Deaf quickly learn sign language and if no one teaches them, they invent one and teach it to each other. A human gene responsible for the structure of the brain, jaw and throat in ways to facilitate language development. More development of the motor cortex in relation to control of vocal cords in comparison to monkeys. A change in the structure of the larynx, enables increased complexity of sounds. There is no easy answer for why humans developed language. Some possibilities are that there is a long period of childhood dependency or social interactions that favored evolution of language. In that case, overall intelligence may be a byproduct of intelligence. Research suggests a sensitive period exists for the learning of language. Lack of early language exposure can lead to permanent impairment. Ease of learning a second language differs with age as well. For instance, adults are better at memorizing vocabulary. Children excel at learning pronunciation and unfamiliar aspects of grammar. Bilingualism has no sharp cutoff existing for second language learning. Those who begin after age 12 rarely gain fluency equal to a native speaker. Most people who are bilingual from a young age show bilateral activity during speech for both languages. Second language learners after age 6 tend to show only left hemisphere activity. Children who begin sign language while still young learn much better than those who start later and in some cases could learn a spoken language later, but if they do not learn the sign language early have great difficulties learning a sign or spoken language later. Aphasia is language impairment and most knowledge of brain mechanisms of language comes from the study of people with brain damage. For instance, the Broca area is part of the left frontal cortex, damage results in some language disability, Broca’s aphasia or nonfluent aphasia impairs language production and its area is not sharply defined (maybe extending to basal ganglia, thalamus, and cerebellum. Serious impairment in language production happens in regions in Broca’s area resulting in only minor or brief language impairment. Speaking activities take most of the brain, not just the Broca’s area. Roles of different brain areas can change. Especially as a result of damage in another area. People with Broca’s aphasia are slow and awkward with all forms of language communication, including sign language, gestures. Reading aloud includes activation of visual cortex, Broca’s,motor cortex. Broca’s area helps to organize the speech but the motor cortex produces it. English speaking people with Broca’s aphasia have difficulties using pronouns, prepositions, helping verbs, and similar words. Prepositions, conjunctions, helping less used. Wernicke’s Aphasia is characterized by impaired language comprehension and impaired ability to remember object names. Also called “fluent aphasia” because the person can still speak smoothly, but omits most nouns and therefore makes little sense. Recognition of items is often not impaired; ability to find words is impaired. Damage usually extended to thalamus and basal ganglia. Also, depending on the word, other brain areas become active. Typical characteristics are articulate fluent speech, except with pauses to find the right word. No problem with prepositions, conjunctions or grammar. Difficulty finding the right word: anomia refers to the difficulty recalling the name of objects. They make up names, use roundabout expressions use words improperly. Poor language comprehension and difficulty understanding speech, writing, and sign language. For people who become fluent in two or more languages, especially for people who have been bilingual since infancy, hemispheric control of the second language comprehension is variable. It might depend mainly on the left hemisphere, the right hemisphere, or both hemispheres about equally. Individual differences are prominent in the ability to learn languages. Language production, independently of how many languages the person know, mainly depends on the left hemisphere. Specific impairment of reading in a person with adequate vision, motivation, and cognitive skill and educational opportunities. It is more common in boys, high heritability, though no common genetic variant, has a large effect. Occurs in all languages and difficulty converting symbols (words) into sounds. People with dyslexia are more likely to have abnormalities in the left hemisphere even before starting reading at an early age. Visual form area, usually on the left hemisphere (whereas facial recognition area usually on the right hemisphere) responds less strongly ro words and more strongly to other objects. The visual word form area, mostly possibly evolved. Out of human beings’ need to detect detailed shapes which facilitate the ability to read. Different people have different kinds of reading problems. Some have problems with poor auditory memory (accuracy or sequencing of tones) , some have impaired eye movements, others both. Difficulty with the temporal order of sounds, which suggests a problem with how the brain handles auditory information, not a problem with the auditory information itself. Alterations in attention: can more easily identify letters slightly to the right of the visual fixation point. Difficulties when letters are too crowded. Overall, not one explanation for all people with dyslexia. n. Describe the brain mechanisms of attention, research on the brain mechanisms of perceptual decisions, and research on the mechanisms of value decisions. Finally, list key findings about biological influences on social behavior. Making a factual decision, we tend to weigh the evidence (which store has lower prices). The brain has several sets of cells- one set that accumulates evidence in favor of the choice, one set that accumulates evidence in favor of the other choice, and one set to compare the two. There was a research study where a rat listened to a set of clicks and then turned his head in the direction with more clicks, since expected there to be a reward. The posterior parietal cortex has two sets of cells that respond to the clicks on each side. The prefrontal cortex had two sets of cells that kept score of which side had more clicks. Studies confirm that certain neurons in the prefrontal cortex, specifically the dorsolateral part of the prefrontal cortex, act as the “scorekeeper.” Other decisions are based on preferences. Typically the basal ganglia gradually learns which choice has the higher payoff based on usual results. Cells in the ventromedial prefrontal cortex modify the responses of the basal ganglia, based on the most recent information. Useful to evaluate new information in relation to habitual types of decisions. Also seems to monitory confidence in one’s decisions. People with damage seems less sensitive to new information. Information is relayed to the orbitofrontal cortex which compares expected rewards to other possible choices. Damage leads to poor or impulsive decision making such as on the Iowa Gambling Task. Some people make better decisions than others. Heart rate variability related to better decisions especially in situations of risk and uncertainty. The bacteria in the digestive system varies in breaking down of proteins, producing short term fatty acids, helping with the immunity. However, soe types of intestinal bacteria produces inflammation, impair cognition and increase risk of psychol;ogical and neurological disorders. When in love, the same brain areas are associated with reward, resembling the effects of addictive drugs. Viewing photos of your loved ones, activates the hippocampus. Oxytocin stimulates contractions of the uterus during childbirth, stimulates breasts to produce milk, promotes maternal behavior, social approach, and pair bonding in many mammalian species. Both men and women release it during sexual activity. Research can be done by giving oxytocin in a nasal spray. Men viewed photos of their significant other and other people. Rated their significant other much higher in attractiveness when given oxytocin. Didn’t increase ratings for others, just magnified from the people they love. Men in a relationship stood further away from an attractive woman when given oxytocin. Enhances fidelity.Oxytocin can affect social relationships because it increases conformity to the opinions of the in-group but now thoutgroup. It also increases attention to possible dangers and heightens reactions to threats especially from strangers. The current hypothesis is that oxytocin increases attention to social cues and intensifies existing relationships. Studies though, with small samples, nasal spray slowly reaches the brain, but not all results are replicated. Civilized life depends on people helping one another. Arrivals other than humans also display concern about others of their species. Dorsomedial prefrontal cortex on differential treatment (helping or not_ to different monkeys based on whether the last ones had behaved to them in the past. Hippocampus and amygdala also. In a study of monkeys, fMRI located a network of neurons in the prefrontal cortex that respond strongly to videos of social behaviors of other monkeys. Similar area to the one that corresponds to the theory of mind for human beings. Some people express more empathy than others do,a large part being culture and upbringing. However, some is biological, for instance, the frontotemporal dementia (includes also frontotemporal lobe-ventromedial and orbito frontal), in which parts of the frontal and temporal lobes of the cerebral cortex gradually degenerate: responsible for evaluating possible rewards and interpreting others’ emotional expressions. People with frontotemporal dementia also exhibit little interest in how others perceive them. According to studies using fMRI, looking at pictures of the person you love strongly activates the brain areas associated with reward, resembling the effects of addictive drugs. o. Explain depressive disorder Major depressive disorder-symptoms include a person feeling sad and helpless most of the day every day for long periods of time, absence and happiness, person does not enjoy anything and cannot imagine enjoying anything/less response of nucleus accumbens to reward. Fatigue, feelings of worthlessness, or contemplation of suicide, trouble sleeping, and cognitive problems including low motivation, impaired memory, concetration problems, and impaired sense of smell. Absence of happiness is a more reliable symptom than increased sadness. Some people suffer long-term depression and it is more common to have periodic episodes of depression. Almost everyone with depression has sleep problems, which generally precede the mood changes. Depression has a moderate degree of heritability, researchers have identified at least 17 common genetic variants linked to depression each with small effects. A study of Chinese women with recurrent severe depression identifies two genes with a strong effect. People with early- onset depression (before age 30) are more likely to have relatives with depression as well as relatives with anxiety disorders, neuroticism, ADD, OCD, IBS, and migraine headaches. Late onset depression (after age 45) linked to relatives with circulatory problems. The above may indicate that there are two different kinds of depression, each one of them linked to different genes. Evolutionary psychologists have proposed the hypothesis that depression could be an adaptation to conserve energy after a defeat. Genetic predisposition may be there, but also immediate triggers. Pain is so closely associated with depression that some languages use the same word for both. Pain decreases the activity of dopamine neurons (important for motivation and reward). Many kinds of stress can cause depression (women after giving birth, around menopause time). Stressful events activate the immune system, preparing the body to attack an infection. The immune system releases proteins, called cytokines, which reduce activity levels and decrease appetite, in order to have the energy to fight the infection. Inactivity and loss of appetite are typical symptoms of depression. Cytokines may produce inflammation and inflammation impairs the activity of the mitochondria, reducing energy. Many people with depression show signs of brain inflammation. Standard antidepressants tricyclics like Tofranil block transporter proteins that reabsorb serotonin, dopamine, and norepinephrine into the presynaptic neuron after release. Side effects include drowsiness, dry mouth, and heart irregularities. Selective serotonin reuptake inhibitors (SSRIs) block the reuptake of the neurotransmitter serotonin. Serotonin norepinephrine reuptake inhibitors (SNRIa) block the reuptake of serotonin norepinephrine. Given the variety of symptoms associated with depression, a combination of antidepressant drugs is often used, though many side effects and not necessarily effective. Monoamine oxidase inhibitors (MAOIs) block enzyme monoamine oxidase that metabolize catecholamines and serotonin into inactive forms, thus more availability of these neurotransmitters. In that case, the person should limit intake of foods containing tyramine, as would lead to high blood pressure. Atypical antidepressants are a miscellaneous group of drugs with antidepressant effects and milder side effects. Inhibits the reuptake of dopamine and to some extent norepinephrine, but not serotonin. Herb often used as a treatment for depression in called St. John’s Wort, not regulated by the FDA, effectiveness about the same as standard antidepressants, and increases the production of a liver enzyme that decreases the effectiveness of other medications. How do antidepressants act most people with depression have normal levels of neurotransmitters. Decreasing serotonin in control groups does not provoke depression. Drugs affect neurotransmitters in synapses quickly (minutes to hours ). Drugs affect neurotransmitters in synapses quickly, but improving mood requires weeks. People with depression have lower than average brain-derived neurotrophic factor (BDNF): important for synaptic plasticity and learning. Standard antidepressants do not bind strongly to receptors of BDNF, they have to accumulate for weeks to reach a high enough brain concentration to produce a significant effect. This is how the delay of effects could be explained.