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Neuro of Reward
Reward and Motivation
Question | Answer |
---|---|
Major aspects include = ? | * liking (e.g., pleasure, hedonia), --- wanting (e.g., motivation for reward, incentive salience), --- learning (e.g., past experiences predicting future rewards) |
System that drives the Reward System = ? | * Neurons containing dopamine are located in the substantia nigra pars impacta and the ventral tegmental area of the ventral midbrain... * Mesostriatal -- Mesolimbic -- Mesocortical |
Mesolimbic Dopamine Pathway = ? | * projects the nucleus accumbens (ventral striatum), but also, to other limbic areas .... * responsible for attaching the “want” (reward) and remembering how we can get it |
Mesocortical dopamine pathway = ? | * Pleasure pathway (we already know we want it, but it is pleasurable to have it) |
The last two pathways = ? | * Overlap = Mesocorticolimbic Pathway |
When stimulated, can cause positive immediate responses ? | * Septal Area |
Reward Pathway = ? | * Main pathway to remember…. VTA --> accumbens --> prefrontal Cortex/cingulate gyrus |
Ventral Tegmental Area (VTA) = ? | * The VTA is the site of dopaminergic neurons which tell the organism whether an environmental stimulus is rewarding or aversive |
Nucleus Accumbens (NAc) = ? | * also called ventral striatum, is a principle target of VTA dopamine neurons. This region mediates the rewarding effects of natural rewards and drugs of abuse. |
Role of the NAc = ? | * Attaches motivation to reward (the want)... * if lesioned, no motivation to want things/do things to get it (lose connection between the reward w/ motivation) |
Once an animal learns how to obtain a reward and the relevant behaviors become engrained, what happens ? | *reward seeking or motivation no longer depends on the NAc but is supported by the dorsal striatum.... * The behavior becomes ‘automated’ (a certain cue can stimulate this) |
Ventral Tegmental Area (VTA) and when we see something we want (ex. a reward) ? | * When we see a reward, VTA Fires and release dopamine in to the NAc… *Attaches a reward with a want |
Patients treated with D2 dopamine receptor agonists, what do we see happen ? | * Can happen in Parkinson's patients... * see new risky behavior/gambling/shopping/etc... *overstimulate the NAc |
Dopamine and reward ? | * Dopamine does not function in mediating pleasure.... * Dopamine circuits play a role in connecting reward-related stimuli to motivation |
Patterns of VTA Dopamine Neuron Firing = ? | * When a reward is predicted from cues and is exactly as expected, firing changes to a tonic pattern. There is no additional release. When the predicted reward is omitted or less than expected, VTA dopamine pause their firing to below basal levels |
Continued... | * If reward is greater, then we see a continued release |
other neurotransmitter systems are also affected ? | * not just Dopamine, but serotonin and glutamate |
Addictive Reward System = ? | * Always better than normal and they don’t shut off the pulse of dopamine (a continued on switch)…increase firing of the VTA ... * sugary or fatty foods can even cause this |
Addiction causes a greater release of dopamine over a greater period of time than natural rewards, and causes what ? | * NAc Dopamine receptors become decreased.... * now they need a greater reward to feel the pleasure |
DA Receptors influence drug liking: explain ? | * Those with already high Dopamine Receptors, are less likely to like the effects of a dopamine agonist.... * If low Dopamine receptor ppl get it, they love the feeling (possible link to who has an addictive personality?) |
Why can't addicts just simply quit = ? | * In Addiction, reward it better than normal, and drive is not shut down.... * Due to a rewiring in brain circuitry |
In control of Inhibitory Control ? | * PFC – prefrontal cortex and the ACG – anterior cingulate gyrus |