Berkeley Blog: Second Semester Subjects Bio-Psych (Part 3)
The most common incidence of drug use is alcohol. 86% of men and 80% of women will drink some form of alcohol in their lives. In low does, alcohol has a stimulant effect by blocking parts of the brain that inhibit (hence, "loosing you inhibitions"). At high doses, however, it acts as a depressant by increasing GABA recepectpros. 25% of people will die of some for of substance abuse. About 1 in 10 develop an alcohol problem, which typically takes about 15 years to develop. There is also strong genetic component. 50% of trauma incidents, 50% of homicides, and 40% of assaults are alcohol related. Chronic usage kills neurons. Korsakoff's syndrome which has the main symptom of permanent amnesia affects predominately alcoholics. However, the disease could be abolished by simply ingesting thiamine. 55% of sufferers end up in prison , in drug/alcohol treatments centers, or mental institutions. The most common cause of mental disability is fetal alcohol syndrome. Cause of the mental retardation is a result of a smaller brain with far fewer neurons, and the absence of the structure that holds the two brain hemispheres together, the corpus callosum.
33% of all smokers will die from their addiction. Of those who attempt to quit, only 4% last more than 6 months. Nicotine increases attention and memory, and also increases the release of dopamine.Marijuana is a $4-25 billion dollar crop in U.S, and costs the U.S. about $4 billion to keep offenders in jail. About 50% of people have tried it. The active ingredient is tetrahydrocannabinol (THC) which has the effect of relaxation, mood alteration, stimulate, hallucination, and paranoia. Cocaine, crack, and methamphetamine all act directly on the dopamine system by increasing its effect. Chronic meth abuse produces a state similar to schizophrenia and are more likely to develop Parkinson's disease. Pain relievers and heroin both activate opioid receptors.
Addiction is characterized by tolerance and withdrawal. Addiction is defined as recurrent failure to control behavior and continuation of behavior despite negative consequences. Drugs differ in their addictive potential. From least to most: Psychedelics, cannabis, caffeine, nicotine, benzodiazepines, alcohol, barbiturates, opiates, amphetamines, cocaine. The more addictive drugs seem to be dealing with accumpus dopamine. Apparently addiction results partly because our neurons never "learn" to properly respond to the drug, they have no "higher cognitive function" except to fire in response to a chemical. Stress early in life can have profound effects. Stressed rats learned more quickly later in life how to self-administer cocaine than the control rats. All drugs of abuse seem to effect the dopamine system.. Addiction might arise because drugs interfere with our normal learning mechanisms for how much we should want something.
We have three main memory systems: short, intermediate, and long term. Is this one system that contains all three, or are they distinct and independent? The primacy and recency effects suggests distinct systems, which says that we tend to recall more information at the beginning and end of lists. Damage to the hippocampus abolishes the primacy effect (long-term memory), while frontal lobe damage abolishes the recency effect (short term memory). "Working memory" is another term for short-term memory. The working memory is the "chalkboard of the mind," where we rehearse and plan. But it has a limited capacity, somewhere around 7 distinct facts can be stored in working memory at one time. If the information in short-term memory does not make it to long term memory, it is lost. The neurons in working memory seem to be different than sensory neurons. They can change what information they encode depending on the demands of the task. These neurons can also "remember" items longer even when faced with distractions. Visual system neurons, for comparison, "forget" their item as soon as something else is presented. Because of this, patients with damage to the prefrontal "working memory" areas of the brain tend to be more distracted and are less likely to complete tasks. The brain chemical dopamine plays a role in working memory, but the brain needs the right balance. Too much dopamine tends to produce stress and psychosis, while too little dopamine creates forgetfulness, distraction and attention disorders. ADHD (Attention-deficit disorder) is a disorder in which patients have difficulty sustaining attention and are easily distracted. Ritalin is used to increase the amount of dopamine in the system.
"HM," an infamous patient who had his both hippocampi removed due to epilepsy, had no long term memory after the point of the surgery. He could remember the distant past, but could not learn new information. On the opposite side, Clive Wearing had no short-term memory and would forget what he was saying as he was saying it. There are different types of long-term memories: declarative, which are things you know that you can tell others, and procedural, which are things you know that you can show by doing. Skill learning such as knowing how to ride a bicycle, and priming and conditioning, are procedural. Whereas episodic such as remembering your first day at school, and semantic, are declarative. Even though animals cannot speak (declare) they still have episodic memories and can remember what happened and when it happened. London Taxi drivers, famous for their ability to memorize every London street, have increased hippocampi volume. The hippocampus provides an index that relates all the elements of an event together. In other words when we "remember" it is the hippocampus that retrieves information from the visual, emotional, or cognitive areas of the brain to create "one" memory. Since many amnesia patients have damage to the hippocampus, they cannot gather the information and "declare it." Amnesia patients can still learn knew skills, however. Procedural memory, conditioning, priming and skill learning, do not need our "conscious." Many amnesia patients, who were taught piano after their injury do not remember learning to play and will tell you so, however, when they sit at a piano they will play it and then find some arbitrary reason as to why they can do it.
There are a number of things that keep our attention. Our visual system is attracted to a single sensory feature that "pops-out," as when 1 vertical line is among 10 horizontal lines. However, our visual search takes longer when two sensory features are shown, as when we scan for color and shape changes. There are two types of cognitive processing: automatic and controlled. Our automatic system is basically an "unconcsious," parallel system, that has no capacity limits and does not require attention. The controlled processing requires our attention, is serially processed, and is limited in capacity. Attention is focused in the parietal lob of our brain above the visual system, and below the motor system. Each hemisphere control the opposite side of the visual system, and one side of our attention system is damaged, we will tend to neglect things in that part of space because the neurons on the non-damaged side are now dominating. Patients with unilateral neglect will fail to report or respond to stimuli presented in one half of space, such as eating exactly half the food on a plate. Their eyes only search half of the space that is available. Visual stimuli compete for attentional resources, and our attention focuses in on the stimuli that produce the biggest response in the neurons. Brightness and contrast are bottom-up, unconscious stimuli that when they strong, "force" our consciousness to pay attention. Novel stimuli tend to win our attention over familiar stimuli.
Not all areas of the brain are equally conscious. Blindsight is when a patient reports they cannot "see" a target but they actually still point to it after encouragement. The reason they can do this is because the eyes are not damaged, the retina and eye neurons still send information to the brain. However, damage in the visual brain system does not allow the patient to be "aware" they can still see. The motor and attention systems are still functional, this is why they can still move and point to it. In other words, damage to the dorsal stream, information flowing from the back of the brain where the visual system is to the bottom (ventral), impairs conscious perception, but leaves intact the ability to unconsciously interact with visual objects. These patients are called agnosics. On the other hand, ataxics, who have dorsal stream damage, have the conscious perception intact, but cannot interact with objects. We cannot perceive two figures at the same time, perception flips between two the alternatives. As such, when two images are presented to the two eyes, we perceive only one. Neurons in our inferior temporal cotex (not visual systems) respond to what we perceive not what we see. Therefor, attention is under voluntary conscious control, but this seems more to apply to perception, while our motor system can use visual information that does not reach consciousness.
Split-brain patients, those who have two completely separate brain hemispheres, become essentially two independent individuals with two minds. However, they cannot show both sides, since the left hemisphere controls language. The right hemisphere cannot speak, so when shown an image to the left side (which the right hemisphere sees), the left hemisphere does not see it, and since language is on the left, the patient says nothing is there. However, the right hemishspere can communicate by writing and pointing (with the left hand). When a split brain patient was asked if they like Richard Nixon, the left hemisphere spoke "yes," while the right hemisphere wrote "no." One patient found his left hand struggling against his right hand to pull up his pants in the morning. His right hand (left hemisphere) wanted to go to work, while his left hand (right hemisphere) wanted to go back to bed. On another occasion he was angry with his wife and attacked her with his left hand (right hemisphere) while his right hand (left hemisphere) defended her from the blow.
The prefrontal cortex dramatic increase in complexity during mammalian evolution suggest it is important for cognitive abilities that are uniquely human. Yet damage to this region only has subtle effects. Careful observation and testing of humans and animals with PFC damage begins to reveal its potential functions. Some of the responsibilities include maintaining information in working memory, which helps us "plan" for future behaviors. Patients with damage to this region where unable to plan ahead for certain tasks, and could not complete the famous "Tower of London" task. The PFC neurons fire more rapidly when we see objects based on current task demands. A single neuron can encode "what" and "where" an object is. This all leads to the conclusion that PFC neurons are not sensory neurons. These neurons are specialized for high-level tasks and inhibit automatic behaviors and simpler learning mechanisms. The "Stroop Test" is an example of a higher-task. The test shows is a written word, say red or blue, but the color of the text is different that what the word says. The subject must say the actual color of word and not the word itself. This is a tricky task and those with damage to the PFC cannot do this. The PFC can be thought of as "executive control" over the other systems of the brain. It implements the strategic goals and objectives of the organism, ensures plans can be flexibly updated in response to changing environmental circumstances, and controls low-levels mechanisms.
33% of all smokers will die from their addiction. Of those who attempt to quit, only 4% last more than 6 months. Nicotine increases attention and memory, and also increases the release of dopamine.Marijuana is a $4-25 billion dollar crop in U.S, and costs the U.S. about $4 billion to keep offenders in jail. About 50% of people have tried it. The active ingredient is tetrahydrocannabinol (THC) which has the effect of relaxation, mood alteration, stimulate, hallucination, and paranoia. Cocaine, crack, and methamphetamine all act directly on the dopamine system by increasing its effect. Chronic meth abuse produces a state similar to schizophrenia and are more likely to develop Parkinson's disease. Pain relievers and heroin both activate opioid receptors.
Addiction is characterized by tolerance and withdrawal. Addiction is defined as recurrent failure to control behavior and continuation of behavior despite negative consequences. Drugs differ in their addictive potential. From least to most: Psychedelics, cannabis, caffeine, nicotine, benzodiazepines, alcohol, barbiturates, opiates, amphetamines, cocaine. The more addictive drugs seem to be dealing with accumpus dopamine. Apparently addiction results partly because our neurons never "learn" to properly respond to the drug, they have no "higher cognitive function" except to fire in response to a chemical. Stress early in life can have profound effects. Stressed rats learned more quickly later in life how to self-administer cocaine than the control rats. All drugs of abuse seem to effect the dopamine system.. Addiction might arise because drugs interfere with our normal learning mechanisms for how much we should want something.
We have three main memory systems: short, intermediate, and long term. Is this one system that contains all three, or are they distinct and independent? The primacy and recency effects suggests distinct systems, which says that we tend to recall more information at the beginning and end of lists. Damage to the hippocampus abolishes the primacy effect (long-term memory), while frontal lobe damage abolishes the recency effect (short term memory). "Working memory" is another term for short-term memory. The working memory is the "chalkboard of the mind," where we rehearse and plan. But it has a limited capacity, somewhere around 7 distinct facts can be stored in working memory at one time. If the information in short-term memory does not make it to long term memory, it is lost. The neurons in working memory seem to be different than sensory neurons. They can change what information they encode depending on the demands of the task. These neurons can also "remember" items longer even when faced with distractions. Visual system neurons, for comparison, "forget" their item as soon as something else is presented. Because of this, patients with damage to the prefrontal "working memory" areas of the brain tend to be more distracted and are less likely to complete tasks. The brain chemical dopamine plays a role in working memory, but the brain needs the right balance. Too much dopamine tends to produce stress and psychosis, while too little dopamine creates forgetfulness, distraction and attention disorders. ADHD (Attention-deficit disorder) is a disorder in which patients have difficulty sustaining attention and are easily distracted. Ritalin is used to increase the amount of dopamine in the system.
"HM," an infamous patient who had his both hippocampi removed due to epilepsy, had no long term memory after the point of the surgery. He could remember the distant past, but could not learn new information. On the opposite side, Clive Wearing had no short-term memory and would forget what he was saying as he was saying it. There are different types of long-term memories: declarative, which are things you know that you can tell others, and procedural, which are things you know that you can show by doing. Skill learning such as knowing how to ride a bicycle, and priming and conditioning, are procedural. Whereas episodic such as remembering your first day at school, and semantic, are declarative. Even though animals cannot speak (declare) they still have episodic memories and can remember what happened and when it happened. London Taxi drivers, famous for their ability to memorize every London street, have increased hippocampi volume. The hippocampus provides an index that relates all the elements of an event together. In other words when we "remember" it is the hippocampus that retrieves information from the visual, emotional, or cognitive areas of the brain to create "one" memory. Since many amnesia patients have damage to the hippocampus, they cannot gather the information and "declare it." Amnesia patients can still learn knew skills, however. Procedural memory, conditioning, priming and skill learning, do not need our "conscious." Many amnesia patients, who were taught piano after their injury do not remember learning to play and will tell you so, however, when they sit at a piano they will play it and then find some arbitrary reason as to why they can do it.
There are a number of things that keep our attention. Our visual system is attracted to a single sensory feature that "pops-out," as when 1 vertical line is among 10 horizontal lines. However, our visual search takes longer when two sensory features are shown, as when we scan for color and shape changes. There are two types of cognitive processing: automatic and controlled. Our automatic system is basically an "unconcsious," parallel system, that has no capacity limits and does not require attention. The controlled processing requires our attention, is serially processed, and is limited in capacity. Attention is focused in the parietal lob of our brain above the visual system, and below the motor system. Each hemisphere control the opposite side of the visual system, and one side of our attention system is damaged, we will tend to neglect things in that part of space because the neurons on the non-damaged side are now dominating. Patients with unilateral neglect will fail to report or respond to stimuli presented in one half of space, such as eating exactly half the food on a plate. Their eyes only search half of the space that is available. Visual stimuli compete for attentional resources, and our attention focuses in on the stimuli that produce the biggest response in the neurons. Brightness and contrast are bottom-up, unconscious stimuli that when they strong, "force" our consciousness to pay attention. Novel stimuli tend to win our attention over familiar stimuli.
Not all areas of the brain are equally conscious. Blindsight is when a patient reports they cannot "see" a target but they actually still point to it after encouragement. The reason they can do this is because the eyes are not damaged, the retina and eye neurons still send information to the brain. However, damage in the visual brain system does not allow the patient to be "aware" they can still see. The motor and attention systems are still functional, this is why they can still move and point to it. In other words, damage to the dorsal stream, information flowing from the back of the brain where the visual system is to the bottom (ventral), impairs conscious perception, but leaves intact the ability to unconsciously interact with visual objects. These patients are called agnosics. On the other hand, ataxics, who have dorsal stream damage, have the conscious perception intact, but cannot interact with objects. We cannot perceive two figures at the same time, perception flips between two the alternatives. As such, when two images are presented to the two eyes, we perceive only one. Neurons in our inferior temporal cotex (not visual systems) respond to what we perceive not what we see. Therefor, attention is under voluntary conscious control, but this seems more to apply to perception, while our motor system can use visual information that does not reach consciousness.
Split-brain patients, those who have two completely separate brain hemispheres, become essentially two independent individuals with two minds. However, they cannot show both sides, since the left hemisphere controls language. The right hemisphere cannot speak, so when shown an image to the left side (which the right hemisphere sees), the left hemisphere does not see it, and since language is on the left, the patient says nothing is there. However, the right hemishspere can communicate by writing and pointing (with the left hand). When a split brain patient was asked if they like Richard Nixon, the left hemisphere spoke "yes," while the right hemisphere wrote "no." One patient found his left hand struggling against his right hand to pull up his pants in the morning. His right hand (left hemisphere) wanted to go to work, while his left hand (right hemisphere) wanted to go back to bed. On another occasion he was angry with his wife and attacked her with his left hand (right hemisphere) while his right hand (left hemisphere) defended her from the blow.
The prefrontal cortex dramatic increase in complexity during mammalian evolution suggest it is important for cognitive abilities that are uniquely human. Yet damage to this region only has subtle effects. Careful observation and testing of humans and animals with PFC damage begins to reveal its potential functions. Some of the responsibilities include maintaining information in working memory, which helps us "plan" for future behaviors. Patients with damage to this region where unable to plan ahead for certain tasks, and could not complete the famous "Tower of London" task. The PFC neurons fire more rapidly when we see objects based on current task demands. A single neuron can encode "what" and "where" an object is. This all leads to the conclusion that PFC neurons are not sensory neurons. These neurons are specialized for high-level tasks and inhibit automatic behaviors and simpler learning mechanisms. The "Stroop Test" is an example of a higher-task. The test shows is a written word, say red or blue, but the color of the text is different that what the word says. The subject must say the actual color of word and not the word itself. This is a tricky task and those with damage to the PFC cannot do this. The PFC can be thought of as "executive control" over the other systems of the brain. It implements the strategic goals and objectives of the organism, ensures plans can be flexibly updated in response to changing environmental circumstances, and controls low-levels mechanisms.
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