Physiological Psychology Final Exam Review EMOTIONS Chapter 11 pgs 367-372 Emotion- refers to positive or negative feelings that are produced by particular situations. Is a behavior Three emotion responses: behavioral, autonomic, and hormonal. Behavioral- consists of muscular movements that are appropriate to the situation that elicits them. Ex. A dog defending its territory against an intruder 1st adopts an aggressive posture, growls, & shows it teeth. If the intruder doesn?t leave, the defender runs toward it & attacks. Autonomic-facilitate the behaviors & provide quick mobilization of energy for vigorous movement. Ex. Activity of the sympathetic branch increases while that of the parasympathetic branch decreases. As a consequence the dog?s heart rate increases, & changes in the size of blood vessels shunt the circulation of blood away from the digestive organs toward the muscles. Hormonal- reinforce the autonomic responses. The hormones secreted by the adrenal medulla-epinephrine and norepinephrine-further increase blood flow to the muscles and cause nutrients stored in the muscles to be converted into glucose. Fear The integration of the components of fear appears to be controlled by the amygdala. Amygdala- plays a special role in physio and behavioral reactions to objects and situations that have biological significance: warn of pain or other unpleasant consequences or signify the presence of food, water, salt, potential mates or rivals or infants in need of care. single neurons in various nuclei of the amygdale become active when emotionally relevant stimuli are presented effects of the olfactory stimuli on reproductive physio and behavior located within the temporal lobes, consists of several groups of nuclei, each with diff inputs and outputs with diff functions Three major regions of the amygdala: lateral nucleus, basal nucleus, and central nucleus. Lateral: receives info from all regions of the neocortex, including the ventromedial prefrontal cortex, thalamus, and hippcampal formation. It also sends info to the basal nucleus and to other parts of the brain including the ventral striatum (region involved in the effects of reinforcing stimuli on learning) and the dorsomedial nucleus of the thalamus, whose projection region is the prefrontal cortex. The Lateral and Basal nuclei send info to the ventromedial prefrontal cortex & the CN Central nucleus (CN)- region that receives info form the basal, lateral, & accessory basal nuclei & sends projections to a wide variety of regions in the brain; involved in emotional responses -single most important part of the brain for expression of emotional responses provoked by aversive stimuli - when central nucleus is destroyed in an animal they no longer shows signs of fear, act very tamely, blood levels of stress hormones are lower & less likely to develop ulcers or other forms of stress-induced illnesses. -when CN stimulated animal shows physio & behavioral signs of fear & agitation and long-term stress Figure 11.2 Pg 369 Amygdala Connections Conditioned Emotional Response-a classically conditioned response that occurs when a neutral stimulus is followed by an aversive stimulus; usually includes autonomic, behavioral, and endocrine components such as changes in heart rate, freezing, and secretion of stress-related hormones -fears are learned Freezing- the animals acted as if they were expecting to receive a shock. Ventromedial prefrontal cortex- plays an important role in controlling the expression of emotional responses. ?its involved in the process of extinction Extinction is not the same as forgetting. The animal learns that the Cs is no longer followed by an aversive stimulus, and as a result of this learning, the expression of the CR is inhibited; the memory for the association between the CS and the aversive stimulus is not erased. Evidence indicates that the amygdala is involved in emotional responses in humans. Most human fears are probably acquire socially, not through firsthand experience with painful stimuli People can also acquire a conditioned fear response through instruction. Also seeing words that denote threatening situations increases the activity of the amygdala. Damage to the amygdala interferes with the effects of emotions on memory. Classic Conditioning A classical conditioned emotional response is established by paring a neural stimulus (such as a tone of a particular frequency) with an aversive stimulus (such as a brief foot shock). After these stimuli are paired, the tone becomes a CS; when it is presented by itself, it elicits the same type of responses as the uncontional stimulus does. When a rat encounters a painful stimulus, somatosensory input activates strong synapses in the lateral nucleus. As a result, the neurons in this nucleus begin firing, which activates neurons in the, CN evoking an unlearned (unconditional) emotional response. If a tone is paired with the painful stimulus, the weak synapses in the lateral amygdala are strengthened through the of the Hebb rule. Lesions of the lateral nucleus of the amygdala disrupt conditioned emotional responses that involve a simple auditory stimulus as a CS and a shock to the feet as a US. The synaptic changes responsible for this learning may take place within this circuit. When an auditory stimulus (CS) is paired with a foot shock (US) the two types of info converge in the lateral nucleus of the amygdala. This nucleus is connected, directly and via the basal nucleus and accessory basal nucleus, with the central nucleus, which is connected with brain regions that control various components of the emotional response. Lesions anywhere in this circuit disrupt the response. Recordings of a single neurons in the lateral nucleus of the amygdala indicate that classical conditioning changes the response of neurons to the CS. The mechanism of synaptic plasticity in this system appears to be NMDA-mediated long-term potentiation. Infusion of drugs that blocks establishment of conditioned emotional responses. LEARNING & MEMORY Learning- refers to the process by which experiences change our nervous system and hence our behavior. We refer to these changes as memories. Experiences are not ?stored?; rather, they change the way we perceive, perform, think & plan. Learning can take at least four basic forms: perceptual learning, stimuli?s-response learning, motor learning, and relational learning. Perceptual learning- the ability to learn to recognize stimuli that have been perceived before Appear to be accomplished primarily by changes in the sensory association cortex. [Recognize by the shape of their faces, the movements they make when they walk, sounds of their voices, etc.] Stimulus-response learning- ability to learn to perform a particular behavior when a particular stimulus is present. Behavior could be an automatic response like a defensive reflex Two major categories of learning: classic conditioning and instrumental conditioning Classical conditioning-form of learning in which an unimportant stimulus acquires the properties of an important one. It involves an association between two stimuli A stimulus that previously had little effect on behavior becomes able to evoke a reflexive, species-typical behavior For example, a defensive eye blink response can be conditioned to a tone. If we direct a brief puff of air toward a rabbit?s eye, the eye will automatically blink. The response is called an unconditional response (UR) because it occurs unconditionally, without any special training. The stimulus that produces it (the puff of air) s called unconditional stimulus (US). Classical conditioning has occurred; the conditional stimulus (CS-the 1000-Hz tone) now elicits the conditional response (CR-the eye blink). Hebb rule says that if a synapse repeatedly becomes active at about the same time that the postsynaptic neuron fires, changes will take place in the structure or chemistry of the synapse that will strengthen it. Another way of describing it is: cellular basis of learning involves strengthening of a synapse that is repeatedly active when the postsynaptic neuron fires. If the 1000-Hz tone is presented first, then weak synapse T (for ?tone?) becomes active. If the puff is presently immediately afterward, then strong synapse P becomes active makes the motor neuron fire. The act of firing then strengthens any synapse with the motor neuron that has just been active. (Of course this means synapse T). After several pairings of the two stimuli and after several increments of strengthening, synapse T becomes strong enough to cause the motor neuron to fire by itself. LEARNING HAS OCCURRED. Overall when weak and strong synapses to a single neuron are stimulated at approx the same time, the weak synapse becomes strengthened! Instrumental conditioning (also called operant conditioning) is a learning procedure whereby the effects of a particular behavior in a particular situation increase (reinforce) or decrease (punish) the probability of the behavior. Involves behavior that has been learned Involves an association between a response and a stimulus More flexible form of learning, it permits an organism to adjust its behavior according to the consequences of that behavior. Behavior followed by favorable consequences will occur more frequently while followed by unfavorable consequences its occurs less frequent Reinforcing stimuli- favorable consequences ex. A response that enables a Hungry organism to find food Punishing stimuli- unfavorable consequences ex. A response that causes pain Motor learning- learning to make a new response The fourth form of learning involves learning the relationships among individual stimuli ex. When we hear the sound of a cat meowing in the dark, we can imagine what a cat looks like and what it would feel like if we stroked its fur. Spatial learning- involves learning about the relationships among many stimuli, perception of spatial location. Episodic learning- remembering sequences of events (episodes) that we witness- requires us to keep track of and remember not only individual events but also the order in which they occur. Interim Summary on the nature of learning Learning produces change in the way we perceive, act, think and feel. It produces change in the nervous system in the circuits responsible for perception, in those responsible for the control of movement, and in connections between the two. Perceptual learning-consists primarily of changes in perceptual systems that make it possible for us to recognize stimuli so that we can respond to them appropriately Stimulus-response learning- consists of connections between perceptual and motor systems. ? Most important forms are classical and instrumental conditioning. Classical occurs when a neutral stimulis is followed by an unconditional stimulus that naturally elicits an unconditional response. Instrumental occurs when a response is followed by a reinforcing stimulus. Motor learning is guided by sensory stimuli, form of stimulus response learning Relational learning, most complex, includes the ability to recognize objects through more than one sensory modality, to recognize the relative location of objects in the environment, and to remember the sequence in which events occurred during particular episodes. Synaptic Plasticity: Long term potentiation and long-term depression Synaptic plasticity changes in the structure of biochemistry of synapses that alter their effects of postsynaptic neurons Long-term potential (LTP)- a long-term increase in the excitability of a neuron to a particular synaptic input caused by repeated high-frequency activity of that input Hippocampal formation- a forebrain structure of the temporal lobe, constituting an important part of the limbic system; includes the hippocampus proper (ammon?s horn), dentate gyrus, and subiculum. ? Specialized region of the limbic cortex Primary input comes from the entorhinal cortex- axons of neurons in the entorhinal cortex pass through the perforant path and form synapses with granule cells of the dentate gyrus. A stimulating electrode is placed in the perforant path, and recording electrode is placed in the dentate gyrus, near the granule cells. 1st a single pulse of electrical stimulation is delivered to the perforant path, and then the resulting population EPSP is recorded in the dentate gyrus. The population EPSP is an extracellular measurement of the excitatory postsynaptic potentials produced by the synapses of the perforant path axons with the dentate granule cells. The size of the 1st pop. EPSP indicates the strength of the synaptic connections before long-term potentiaiton has taken place. Long-term potentiation can be induced by stimulating the axons in the perforant path with a burst of approx one hundred pulses of electrical stimulation, delivered within a few seconds. Evidence that long-term potentiation has occurred is obtained by periodically delivering single pulses to the perforant path and recording the response in the dentate gyrus. If the response is greater than it was before the burst of pulses was delivered, long-term potentiation has occurred. LTP can last for several months Associative long-term potentiation- a LTP in which concurrent stimulation of weak and strong synapses to a given neuron strengthens the weak ones. Role of NMDA Receptors A series of pulses delivered at a high rate all in one burst will produce LTP, but the same # of pulses given at a slow rate will not. ? In fact low-frequency stimulation can lead to long-term depression. NMDA receptor- a specialized ionotropic glutamate receptor that controls a calcium channel that is normally blocked by Mg2+ ions; involved in LTP Found in the hippocampal formation, especially in field CA1 Named from a drug that specially activates it: N-methyl-D-aspartate Controls a calcium ion channel, channel usually blocked by a magnesium ion, which prevents calcium ions from entering the cell when the receptor is stimulate by glutamate. But if the postsynaptic membrane is depolarized, the mg2+ is ejected from the ion channel, and the channel is free to admit Ca2+ ions. Thus calcium ions enter the cells through the channels controlled by NMDA receptors only when the postsynaptic membrane is depolarized. This means that the ion channel is controlled by the NMDA receptor is a neurotransmitter and voltage-dependent ion channel. The entry if calcium ions through the ion channels controlled by NMDA receptors is an essential step in LTP. AP5- a drug that blocks NMDA receptors prevents Ca ions from entering the dendritic spines and thus blocks the establishment of LTP. Therefore this indicating that the activation of NMDA receptors is necessary for the 1st step in the process events that establishes LTP: the entry of calcium ions into dendritic spines. Dendritic spike- action potential that occurs in the dendrite of some types of pyramidal cells. Study in 1997 by Magee and Johnston proved that the simultaneous occurrence of synaptic activation and a dendritic spike strengthens the active synapse. AMPA receptor- an ionotropic glutamate receptor that controls a sodium channel; when open, it produces EPSPs. Control sodium channels; thus, when they are activated by glutamate, they produce EPSPs in the membrane of the dendritic spine. Therefore with more AMPA receptors present the release of glutamate by the terminal button causes a larger excitatory post-synaptic potential, and the synapse becomes stronger How does the entry of calcium ions into the dendritic spine cause AMPA receptors to move into the postsynaptic membrane? ? The process involves several enzymes, including CaM-KII. CaM-KII- Type II calcium- calmodulin kinases, an enzyme that must be activated by calcium; may play a role in the establishment of LTP Found in dendritic spines Inactive until a calcium ion binds with it and activates it Many studies have found that the establishment of LTP includes changes in the size and shape of dendritic spines (enlargement of thin spines into fatter, mushroom-shaped spines). & caused the growth of new dendritic spines. Classical Conditioning (see classical conditioning above) Instrumental conditioning (IC) IC means by which we and other animals profit form experience. IC entrails the strengthening of connections between neural circuits that detect a particular stimulus and neural circuits that produce a particular response There are 2 major pathways between sensory association cortex & motor association cortex: --Direct transcortical connections (connections from 1 area of the cerebral cortex to another) -Connections via the basal ganglia and thalamus. Transcortical connections: involved in the acquisition of episodic memories, acquisition of complex behaviors that involve deliberation or instruction. At 1st performing a behavior through observation or by following a set of rules is slow and awkward however with practice it becomes second nature. Once a learned behavior becomes automatic & routine it?s transferred to the basal ganglia. Studies found that lesions of the basal ganglia disrupt instrumental conditioning but not other forms of learning. Reinforcement The activity of dopamingergic neurons plays a particularly important role in reinforcement. Ventral tegmental area (VTA) ? a group of dopamingergic neurons in the ventral midbrain whose axons form the mesolimbic and mesocortical systems; plays a critical role in reinforcement. Nucleus accumbens- a nucleus of the basal forebrain near the septum; receives dopamine-secreting terminal buttons (TB) from neurons of the ventral tegmental area and is thought to be involved in reinforcement and attention. Microdialysis- enables an investigator to analyze contents of the interstitial fluid within a specific region of the brain. Reinforcement System Reinforcement system must perform 2 functions: detect the presence of a reinforcing stimulus (recognize that something good has just happened) and strengthen the connections between the neurons that detect the discriminative stimulus (such as the sight of a lever) and the neurons that produce the instrumental response (a lever press). Reinforcement occurs when neural circuits detect a reinforcing stimulus and cause the activation of dopamingergic neurons in the ventral tegemental area. Detection of a reinforcing stimulus is not a simple matter; its not automatically activated when particular stimuli a represent; its activation depends on the state of the animals (ex. For food whether they are hungry or just ate). Anticipation of a reinforcing stimulus increased activation of the entral tegmentum and some of its regions (including nucleus accumbens) in humans. The prefrontal cortex provides an important input to the ventral tegmental area. The TBs of the axons connecting these 2 areas secrete gkutamate, an excitatory meurotransmitter (NT) and the activity of these synapses makes dopaminergic neurons in the ventral tegmental area fire in a bursting pattern, which greatly increases the amt of dopamine they secrete in the nucleus accumbens. Prefrontal cortex- generally involves in devising strategies, making plans, evaluating progress made toward goals, and judging the appropriateness of one?s own behavior. Strengthening Neural Connections: Dopamine and Neural Plasticity Instrumental conditioning involves 3 elements: a discriminative stimulus, a response, and a reinforcing stimulus Several studies have show that LTP essential for instrumental conditioning and that dopamine is an essential ingredient in long-lasting LTP. Smith-Roe and Kelley found that the presence of dopamine and the activation of NMDA receptors in the nucleus accumbens both appear to be necessary for instrumental conditioning to take place. The prefrontal cortex is a target of dopaminergic neurons as well as a source of their control. Dopamine modulate LTP in the prefrontal cortex as well as in the nucleus accumbens. Numerous studies have found that dopamine plays a modulating role in the synaptic plasticity in parts of the brain that are involves in learning. Notes interim summary on pg 465 instrumental conditioning Relational learning Anterograde amnesia- difficulty in learning new info. Cannot retain info encountered after the damage. Hippocampal lesions produced anterograde amnesia Brain damage can produce anterograde amnesia, which consists of the inability to remember events that happen after the damage occurs, even though short-term memory (such as that needed to carry on a conversation) is largely intact. Anterograde amnesia can be caused by chronic alcoholism (Korsakoff?s syndrome), which primarily damages the mammillary bodies or it can be produced by bilateral damage to the medial temporal lobes. Anterograde amnesia- Ability of the brain to consolidate short-term memories into long-term was damaged. Ordinary, perceptual learning, stimulus-response learning and motor learning didn?t seem to be impaired Ppl can learn to recognize new stimuli, are capable of instrumental and classical conditioning and can acquire motor memories. However they aren?t capable of declarative learning-describing events that happen to them. Researchers state that the primary cause of anterograde amnesia is damage to the hippocampal formation or to its inputs and outputs. Temporal anoxia damages field CA1 because of the high concentration of NMDA receptors there and produces anterograde amnesia. The entorhinal cortex receives info from all regions of the association cortex, directly & through its connections with the perirhinal and parahippocampal cortex that surrounds it. The outputs of the hippocampal formation are relayed through these same regions. Hippocampal formation receives info from other regions of the brain, processes this info then through its efferent connections with these regions, modifies the memories, that are being consolidated there, linking them together in ways that will permit us to remember the relationships among the elements of the memories. The hippocampal formation especially the right posterior hippocampus- is involved in spatial memory. Damages in the hippocampal formation disrupts the ability to learn spatial relations. Retrograde amnesia- inability to remember events that happened before the brain damage Anterograde amnesia patients are capable of variety of tasks that require perceptual learning, stimulus response learning, and motor learning. However, although the patients can learn to perform these tasks, they do not remember anything about having learned them. They do not remember the experimenters, the room in which the training took place, the apparatus that was used, or any events that occurred during the training. Declarative memory- memory that can be verbally express, such as memory for events in a person?s past ex. Last years birthday, remembering past experiences, finding one?s way in new environment Nondelcarative memory- memory whose formation doesn?t depend on the hippocampal formation; a collective term for perceptual, stimulus-response, and motor memory. Ex. Learning to ride a bike, learning to recognize broken drawings, learning to recognize picture and objects, faces, melodies, classical conditioning (eye blink), instrumental conditioning (choose circle), and learning sequence of button presses Perirhinal cortex- a region of limbic cortex adjacent to the hippocampal formation, along with the parahippocampal cortex, relays info between the entorhinal cortex and other regions of the brain. Parahippocampal cortex- a region of limbic cortex adjacent to the hippocampal formation that, along with the perirhinal cortex, relays info between the entorhinal cortex and other regions of the brain. Ca1 ? of the hippocampus is so sensitive to anoxia because of the fact that this region is especially rich in NMDA receptors. Metabolic disturbances of various kinds (seizures, anoxia, etc) cause glutamatergic terminal buttons to release glutamate at abnormally high levels. The effect of this glutamate release is to stimulate NMDA receptors, which permit the entry of calcium. Within a few mins, excessive amts of intracellular calcium begin to destroy the neurons. Episodic & Semantic Memories Episodic memory- memory of a collection of perceptions of events organized in time and identified by a particular context Semantic memory- a memory of facts and general info Semantic dementia- loss of semantic memories caused by progressive degeneration of the neocortex of the lateral temporal lobes Semantic info is lost but episodic memory for recent events can be spared Spatial Memory Bilateral medial temporal lobe lesions produce the most profound impairment in spatial memory Place cells- a neuron that becomes active when the animal is in a particular location in the environment; most typically found in the hippocampal formation Neurons that are directly involved in navigation in space. Spatial task activated the hippocampus and the response task activated the caudate nucleus (a component of the basal ganglia). Hippocampus is activated in subjects who follow a spatial strategy (correlated on how to learn a maze, either spatial or through a series of turns) Caudate nucleus was activated in subjects who followed the response strategy. Ppl who tended to follow a spatial strategy in a virtual maze has a larger-than-average hippocampus, and ppl who tended to follow a response strategy has a larger than average caudate nucleus Hippocampal lesions disrupt the ability to keep track of and remember spatial locations. Ex. H.M. never learned to find his way home when his parents moved after his surgery. Results from rat study: if rats with hippocampal lesions are always released from the same place, they learn this is nonrelational, stimulus-response task about as well as normal rats do. However, if they are released from a new position on each trial, they swim in what appears to be aimless fashion until they finally encounter the platform. Experimenters (okeefe and dostrovsky) found that some neurons fired at a high rate only when the rate was in a particular location. Diff neurons had diff spatial receptive fields; that is, they responded when the animals were in diff locations. The hippocampus appears to receive its spatial info from the parietal lobes by means of the entrohinal cortex Damage to the entorhinal cortex disrupts the spatial receptive fields of place cells in the hippocampus and impairs the animals ability to navigate in spatial tasks Rats with the T-maze experiment established that pyramidal cells in CA1 encode both the current location and the intended destination. The firing patterns of hippocampal place cells with spatial receptive fields in the stem of the maze were diff on trails during which the animals turned left or right. Hippocampal formation plays a critical role in consolidation of relational memories Hippocampus required for newly learned spatial information but not for information learned thirty days previously DRUG ABUSE Chapter 18 pg 614-630 Positive Reinforcement Positive reinforcement refers to the effect that certain stimuli have on the behavior that preceded them. If in a particular situation, a behavior is regularly followed by an appetitive stimulus (one that the organism will tend to approach), then that behavior will become more frequent in that situation. Ex. If a hungry rat accidentally bumps into a lever and receives some food, the rat will eventually learn to press the lever. Addictive drugs have reinforcing effects; their effects include activation of the reinforcement mechanism. If the drug was taken by a fast-acting route such as injection or inhalation, the last response will be the act of taking the drug, so that response will be reinforced. This form of reinforcement is powerful and immediate and works with a wide variety of species. Role in Drug Abuse The effectiveness of a reinforcing stimulus is greatest if it occurs immediately after a response occurs. If the reinforcing stimulus is delayed, it becomes considerably less effective. Ex. Of the immediacy of reinforcement. Study by Logan with rats: Logan trained hungry rats to run through a simple maze in which a single passage led to two corridors. At the end of one corridor the rate would fine a small piece of food. At the end of the other corridor they would receive much more food, but it would be delivered only after a delay. Although the most intelligent strategy would be to enter the 2nd corridor and wait for the larger amt of food, the rats chose to take the small amt of food that was delivered right away. IMMEDIACY OF RENIFORCEMENT TOOK PRECEDENCE OVER QUANTITY. The most addictive drugs like heroin are chose because of the rapid effect and not necessarily the different effect. The immediate reinforcing effects of an addictive drug can, for some individuals, overpower the recognition of the long-term aversive effects. Neural Mechanisms All natural reinforces that have been studies so far have one physio effect in common: they cause the release of dopamine in the nucleus accumbens The release of dopamine appears to be a necessary (but no sufficient) condition for positive reinforcement to take place The process of addiction appears to begin in the mesolimbic dopaminergic system and then produce long-term changes in other brain regions that receive input from these neurons First changes appear to take place in the ventral tegmental area (VTA) Addition in humans involves the dorsal striatum The control of compulsive addictive behavior is established by interactions between the ventral and dorsal striatum that are mediated by dopaminergic connections between these regions and the VTA Negative Reinforcement Negative reinforcement- the removal or reduction of an aversive stimulus that is contingent on a particular response, with an attendant increase in the frequency of that response The response must make the unpleasant stimulus end (or at least decrease) For punishment to occur the response must make the unpleasant stimulus end (or at least decrease). Tolerance- decreased sensitivity to a drug that comes from its continued use Once someone has taken an opiate regularly enough to develop tolerance, that person will exhibit withdrawal symptoms if he or she stops taking the drug Withdrawal symptoms are primarily the opposite of the effects of the drug itself Craving and Relapse Drug addiction involves ?a cycle of spiraling dysregulation of brain reward systems that progressively increases, resulting in the compulsive use and lose of control over drug-taking Lesions of the vmPFc impair the extinction of a conditioned emotional response, that stimulation of this region inhibits conditioned emotional response, and that extinction training activate neurons located there The dACC plays a role in craving and the vmPFC plays a role in its suppression The cortical regions most often activate include the ACC and orbitofrontal cortex Activation of the prefrontal cortex appears to be related to craving for normal reinforcers as well for addictive drugs Up to half or of all people with schizophrenia have a substance abuse disorder (alcohol or illicit drugs) and 70 to 90 percent are nicotine dependent With addiction and abusive drugs a decrease of gray matter is shown Abnormalities in the prefrontal cortex may be a common factor in schizophrenia and substance abuse disorders The role of the prefrontal cortex in judgment, risk taking, and control of inappropriate behaviors may explain why adolescents are much more vulnerable to drug addiction than adults. Adolescent is a time of rapid and profound maturational change in the brain?particularly in the prefrontal cortex Stress that occurs early in life can have long-lasting effects Interim Summary All addictive drugs that produce positive reinforcement stimulate the release of dopamine in the NAC, a structure that plays an important role in reinforcement Positive reinforcement occurs when a behavior is regularly followed by an APPETITIVE STIMILUS Negative reinforcement occurs when a behavior is followed by the REDUCTION or TERMINATION of an AVERSIVE STIMULUS The vmPFC plays an inhibitory role in reinstatement, and the dACC plays a facilitatory role Opiates Derived from a stocky resin produce by opium poppy, has been eaten and smoked for centuries A person must take increasing amts of the drug to achieve a ?high? Three major types of opiate receptors are mu, delta, and kappa The mu receptors and delta receptors are responsible for reinforcement and analgesia and that stimulation of kappa receptors produces aversive effects Naloxone-a drug that block mu opiate receptors; antagonizes the reinforcing and sedative effects of opiates Pimozide- a drug that blocks dopamine receptors Antagonize-precipitated withdrawal- sudden withdrawal from long-term administration of a drug caused by cessation of the drug and administration of an antagonistic drug A single dose of an opiate decreases the firing rate of neurons in the locus coeruleus, but if the drug is administered chronically, the firing rate will return to normal Stimulant Drugs: Cocaine and Amphetamine Act as potent dopamine agonists Cocaine binds with and deactivates the dopamine transporter proteins, thus blocking the reuptake of dopamine after it is released by the terminal buttons Amphetamine also inhibits the reuptake of dopamine, but its most important effect is directly stimulate the release of dopamine from terminal buttons Freebase cocaine (crack) is smoked and thus enters the blood supply of the lungs and reaches the brain very quickly. Because its effects are so potent and so rapid, it is probably the most effective reinforcer of all available drugs When people take cocaine, they become euphoric, active and talkative Study found that rats that self-administered cocaine were almost 3 times more likely to die than were rats that self-administered heroin The mesolimbic dopamine system plays an essential role in all forms of reinforcement, except perhaps for the reinforcement that is mediated by stimulation of opiate receptors Nicotine The WHO (world health organization) estimates that 50% of the ppl who begin to smoke as adolescents and continue to smoking throughout their lives will die from smoking-related diseases Investigators estimate that by the year 2015, tobacco will be the largest single health problem worldwide, with 6.4 million deaths per year Nicotine stimulates nicotine acetylcholine receptors, it also increases the activity of dopaminergic neurons of the mesolimbic system and causes dopamine to be released in the NAC Reinforcing effect of nicotine appears to be caused by activation of nicotinic receptors in the ventral tegmental area Rimonabant- drug that blocks canabinoid CB1 receptors, reduces nicotine self-administration and nicotine-seeking behavior in rats By blocking CB1 receptors, rimonabant decreases the reinforcing effects of nicotine Nicotine has dual effects on nicotinic receptors: activation and then desensitization Cessation of smoking after long-term use causes withdrawal symptoms, including anxiety, restlessness, insomnia, and inability to concentrate The insula part of the brain has the highest association with cessation of smoking Alcohol Alcohol has two primary sites of action: it serves as an indirect agonist at GABAa receptors and as an indirect antagonist at NMDA receptors At low doses alcohol produces mild euphoria and has an anxiolytic effect- that is, it reduces the discomfort of anxiety. At higher doses, it produces incoordination and sedation Alcohol removes the inhibitory effect of social controls on their behavior Alcohol produces both positive and negative reinforcement Positive: mild euphoria Negative: termination of an aversive stimulus. If a person feels anxious and uncomfortable, then an anxiolytic drug that relieves this discomfort provides at least temporary escape from an unpleasant situation Major Affective Disorders Bipolar disorder- a serious mood disorder characterized by cyclical periods of mania and depression. Major depressive disorder (MDD)- a serious mood disorder that consists of unremitting depression or periods of depression that do not alternate with periods of mania Episodes of mania are characterized by a sense of euphoria that doesn?t seem to be justified by circumstance. Ppl with mania usually exhibit nonstop speech and motor activity. They flip from topic to topic and often have delusions, but they lack the severe disorganization that is seen in schizophrenia. They frequently go with long periods without sleep, working furiously on projects that are often unrealistic Evidence indicates that a tendency to develop an affective disorder is a heritable characteristic Rosenthal (1971) found that close relatives of ppl who suffer from affective psychoses are ten times more likely to develop these disorders than are ppl without afflicted relatives The strongest candidate is the gene for the serotonin transporter Treatments MDD treatments: monoamine oxoidase inhibitors, drugs that inhibit the reuptake of norepinephrine or serotonin, or interfere with NMDA receptors, electroconvulsive therapy, transcranial magnetic stimulation (more on pg 573) Bipolar disorder treatment: lithium and some anticonvulsant drug Iproniazid inhibits the activity of MAO, which destroys excess monoamine transmitter substance within terminal buttons Tricyclic antidepressants- a class of drugs used to treat depression; inhibits the reuptake of norepinephrine and serotonin but also affects other neurotransmitters; named for molecular structure Specific serotonin reuptake inhibitors (SSRI)- an antidepressant drug that specifically inhibits the reuptake of serotonin without affecting the reuptake of other neurotransmitters Ex. Prozac, celexa, and paxil Serotonin and norepinephrin reuptake inhibitor (SNRI)- an antidepressant drug that specifically inhibits the reuptake of norepinephrine and serotonin without affecting the reuptake of other transmitters Electroconvulsive therapy (ECT)- a brief electrical shock, applied to the head, that results in an electrical seizure; used therapeutically to alleviate severe depression Treatment-resistant depression- a major depressive disorder whose symptoms are not relieved after trials of several diff treatments. ECT decreases brain activity and raises the seizure threshold of the brain, making it less likely for another seizure to occur. The increased seizure threshold appears to be caused by an increased release of GABA and neuropeptide Y Subgenual anterior cingulated cortex (subgenual ACC)- a region of the medial prefrontal cortex located below the ?knee? at the front of the corpus callosum; plays a role in the symptoms of depression Lithium- a chemical element; lithium carbonate is used to treat bipolar disorder Monoamine hypothesis- a hypothesis that states that depression is caused by low level of activity of one or more monoaminergic synapses Tryprophan depletion procedure- a procedure involving a low tryptophan diet and a tryprophan-free amino acid ?cocktail? that lowers brain tryptophan and consequently decreases the synthesis of 5-HT Tryptophan depletion caused most of the patients to relapse back into depression Serotonin and norepinephrine have an affect on depression The amygdala and several regions of the prefrontal cortex play special roles in the development of depression Amygdala is critically involved in the expression of negative emotions Another region of the medial prefrontal cortex, the subgenual ACC, shows a lower level of activation in depression patients. Depressed patients who initially exhibited a low response to emotional stimuli in the subgenual ACC and a high response in the amygdala responded best to cognitive behavior therapy Research has found that cognitive behavior therapy is the most effective form of psychotherapy for depression Interim Summary: Major Affective Disorders Depression seems to be caused by insufficient activity of monoaminergic neurons 5-HT plays a role in mood Stressful live experiences increase the likelihood of depression in ppl with or two short alleles of the 5-HT transporter promoter gene, and a better response to antidepressant treatment is seen in depressed people with two long alleles Stressful experiences suppress hippocampal neurogensis, and antidepressant treatments increase it. Sleep disorders are characteristic of affective disorders Phototherapy- treatment of seasonal affective disorder by daily exposure to bright light Seasonal affective disorder (SAD)- a mood disorder characterized by depression, lethargy, sleep disturbances, and craving for carbs during the winter season when days are short Anxiety and Stress Disorders Anxiety disorder- a psychological disorder characterized by tension, over activity of the autonomic nervous system, expectation of an impending disaster, and continuous vigilance for danger. Panic disorder- a disorder characterized by episodic periods of symptoms such as shortness of breath, irregularities in heartbeat, and other autonomic symptoms, accompanied by intense fear Anticipatory anxiety- a fear of having a panic attack; may lead to development of agoraphobia Agoraphobia- a fear of being away from home or other protected areas Generalized anxiety disorder- a disorder characterized by excessive anxiety and worry serious enough to cause disruption to one?s life Social anxiety disorder- a disorder characterized by excessive fear of being exposed to the scrutiny of other people that leads to avoidance of social situations in which the person is called on to perform Obsessive-compulsive disorder (OCD)- a mental disorder characterized by obsessions and compulsions Obsession- an unwanted thought or idea with which a person is preoccupied Compulsion- the feeling that one is obliged to perform a behavior, even if one prefers not to do so ex. Counting, checking, cleaning, and avoidance ? ppl might repeatedly check burners on the stove to see that they are off and windows and locks to be sure that they are locked Tourette?s syndrome- a neurological disorder characterized by tics and involuntary vocalizations and sometimes by compulsive uttering of obscenities and repetition of the utterances of others Interim Summary: Anxiety Disorders Panic disorders is at least partly heritable, which suggests that it has biological causes Panic attacks can be triggered in many susceptible people by conditions that activate the autonomic nervous system, such as caffeine, yohimbine, injection of lactate, or inhalation of air containing elevated amt of carbon dioxide. First choice of medical treatment for panic attacks is an SSRI OCD has a heritable basis and is related to Tourette?s syndrome, a neurological disorder characterized by tics and strange verbalizations It can also be caused by brain damage at birth, encephalitis, and head injuries, especially when the basal ganglia is involved Functional imaging indicates that ppl with obsessive-compulsive disorder tend to show increased activity in the orbitofrontal cortex, cingulate cortex, and caudate nucleus The most effective drugs are SSRIs such as clomipramine Stress Disorders Stress- a general, imprecise term that can refer either to a stress response or to a situation that elicits a stress response Stress response- a physiological reaction caused by the perception of aversive or threatening situations Fight or flight response- a species- typical response preparatory to fighting or fleeing; thought to be responsible for some deleterious effects of stressful situations on health Glucocorticoid- one of a group of hormones of the adrenal cortex that are important in protein and carb metabolism, secreted especially in times of stress Corticotrophin-releasing hormone (CRH)- a hypothalamic hormone that stimulates the anterior pituitary gland to secrete ACTH (adrenocorticotropic hormone) Adrenocoricotropic hormone (ACTH)- a hormone released by the anterious pituitary gland in response to CRH; stimulates the adrenal cortex to produce glucocorticoids Posttraumatic stress disorder (PTSD)- a psychological disorder caused by exposure to a situation of extreme danger and stress; symptoms include recurrent dreams or recollections can interfere with social activities and cause a feeling of hopelessness Psychoneuroimmunology- the branch of neuroscience involved with interactions between environmental stimuli, the nervous system, and the immune system Antigen-a protein present on a microorganism that permits the immune system to recognize the microorganism as an invader Antibody- a protein produce by a cell of the immune system that recognizes antigens present on invading microorganisms B-lymphocyte- a white blood cell that originates in the bone marrow; part of the immune system Immunoglobulin- an antibody released by B-lymphocytes that bind with antigens and help to destroy invading microorganisms T-lymphocyte- white blood cell that originates in the thymus gland; part of the immune system Cytokine- a category of chemicals released by certain white blood cells when they detect the presence of an invading microorganism; causes other white blood cells to proliferate and mount an attack against the invader Interim Summary: Stress disorders Ppls emotional reactions to aversive stimuli can harm their health Acute stress can also impair hippocampal functioning Exposure to stress during prenatal or early postnatal life can affect brain development, resulting in impaired functions of the hippocampus and increased size of the amygdala Stress if chronic pain can cause loss of cerebral gray matter, especially in prefrontal cortex, with accompanying deficits in behaviors that involve the prefrontal cortex Exposure to extreme stress can have long lasting effects, can lead to the development of posttraumatic stress disorder Associated with memory deficits, poorer health, and a decrease size of the hippocampus The immune system consists of several types of white blood cells that produce both nonspecific and specific responses to invading microorganisms Nonspecific responses include the inflammatory response, the antiviral effect of interferon, and the action of natural killer cells against viruses and cancer cells Specific responses include chemically mediated and cell-mediated responses Chemically mediated are carried out by B-lymphocytes which release antibodies that bind with the antigens on microorganisms and kill them directly or target them for attack by other white blood cells Cell mediated are carried out by t-lymphocytes, whose antibodies remain attached to their membranes
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