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64 Cards in this Set
- Front
- Back
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What is the thalamus?
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a relay center for incoming sensory information and outgoing motor information; acts as a filter to fine-tune incoming and outgoing information
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What does the hypothalamus do?
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receives neurochemical signals from the brain and neuroendocrine signals from the body to regulate homeostasis and drive behavior towards homeostasis
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What does the amygdala do?
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receives information from all modalities and processes information regarding unconditioned fear and reward and conditioned fear and reward
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What is the hippocampus involved in?
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memory consolidation and recall.
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What does the cortex do?
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associates information from many brain regions and is involved in executive functions
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The striatum is a motor interface. What does that mean?
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it connects many nonmotor structures with the primary motor cortex via the basal ganglia.
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What is in the Dorsal striatum?
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caudate and putamen
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What is in the Ventral striatum?
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nucleus accumbens
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What is the nucleus accumbens?
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a small structure in the diencephalon that is highly involved in turning motivation into action
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What does the nucleus accumbens do?
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-receives information from all other
limbic regions (decisions from PFC, memory from hippocampus, emotion from amygdala, and motivation from hypothalamus, also input from midbrain monoamine systems) -Considered the start of the motor output of the limbic system; “limbic-motor interface”. -The nucleus accumbens sends information to the motor component of the limbic system to produce a behavioral output (approach vs. avoid) |
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What is considered the brains reward center?
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nucleus accumbus
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What happens when there is damage to the accumbens?
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-Reduction in eating, drinking, sex,
drug-taking -Reduction in intracranial selfstimulation (electrical stimulation of the brain’s reward pathways) |
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What disorder would have low nucleus accumbens activity?
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depression
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What disorder would have high nucleus accumbens activity?
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addiction
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In addition to turning motivation into action, the nucleus accumbens is also involved in...
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attention
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Nucleus accumbens responds to...
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new or important items in the environment and then motivates the animal to act accordingly (approach or avoid)
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The nucleus accumbens is rich in...
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dopamine receptors and receives
dopamine signals from the ventral tegmental area (VTA). |
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Where is the ventral tegmental area (VTA) located?
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in the tegmentum
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How does nucleus accumbens work?
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Good stuff -> NAC activated ->
approach the good stuff Bad stuff -> NAC activated -> avoid the bad stuff |
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What does blocking dopamine receptors in the nucleus accumbens do?
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makes animals work MORE for electrical stimulation
-stimulation not as rewarding so need more stimulation-> more lever pressing |
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What does enhancing dopamine transmission (giving amphetamine) do?
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-makes an animal work LESS for electrical stimulation
-stimulation is more rewarding so need less stimulation -> less lever pressing |
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What does Wellbutrin do?
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a dopamine reuptake inhibitor (like cocaine but not as strong) that effectively treats some forms of depression
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What does Wellbutrin=Zyban do?
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“no smoking pill”
-The idea is to elevate dopamine first so that the ability of nicotine to elevate dopamine is not detected -> no rise in dopamine by nicotine -> no motivation to smoke or attention to smoking -> stop smoking |
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Dopamine levels rise in the nucleus accumbens in response to...
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appetitive AND aversive situations
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Dopamine goes up in the nucleus accumbens when...
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-Having sex, eating food, drinking water, being shocked etc.
-Taking drugs of abuse -All addictive drugs increase dopamine in the nucleus accumbens! |
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What do drugs of abuse do to the accumbens?
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sensitize dopamine
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What is the dopamine hypothesis of addiction?
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The ability of drugs of abuse to elevate and to sensitize this elevation in nucleus accumbens levels of dopamine is responsible in part for the increased attention to and/or motivation for the effects
of the drug and the motivation to keep taking the drug (addiction) |
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What leads to addiction?
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-Chronic stimulant use decreases the number of dopamine transporters in your nucleus accumbens
-Less transporters -> less reuptake -> more dopamine in synapse -> higher motivation for drug + greater attention to drug -> addiction |
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What is considered the critical
pathology in addiction and other disorders? |
A dysregulation of the circuit involving the VTA, nucleus accumbens, prefrontal cortex and amygdala
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What is the basal ganglia?
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similar to the limbic system in that it is
also a circuit of inter-connected brain regions |
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What is the key role of the basal ganglia?
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-the initiation, coordination and control of motor movements
-procedural memory (the memory of performing an act; e.g. riding a bike, writing) -“habit” circuit of the brain and can be, but is not necessarily, driven by emotionally or motivationally relevant items |
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Where is the limbic system and the basal ganglia located?
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diencephalon and mesencephalon, where they curve around the thalamus
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The limbic system and the basal ganglia receive inputs from...
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from structures in both the diencephalon and the midbrain
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Both the limbic system and the basal ganglia are surrounded by...
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cortex enabling these circuits to receive primary, secondary and associative sensory information and to send motor information to the primary and secondary motor cortices
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Where does dopamine originate in the basil ganglia?
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substantia nigra (black substance; SN)
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Where is the substania nigra (SN) located?
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the tegmentum
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The substania nigra (SN) is so called because...
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it is high in the dark pigment, melanin
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The SN sends neurons to
a region called the... |
caudate-putamen (in primates) or the dorsal striatum (in lower mammals not divided)
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The nigro-striatal dopamine system is so-called because...
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it originates in the substantia nigra (nigro) and projects to the dorsal striatum (striatal)
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Why is the nigro-striatal dopamine system important?
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for the consolidation and recall of procedural memory (learned motor
patterns and habits) |
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What do stimulant drugs do to dopamine levels in stratium?
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increase!
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Hyper-activation of the nigro-striatal dopamine pathway does what with each stimulant experience?
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sensitizes (gets bigger)
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How do habits form?
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The sensitization of dopamine transmission in the striatum accounts for the sensitization of motor behaviors with repeated drug use -> habit formation
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Hyper-activation of the nigro-striatal dopamine pathway leads to what?
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motor hyperactivity -> ADHD
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Hyper-activation of the nigro-striatal dopamine pathway causes....
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fidgeting, leg bouncing, finger tapping, picking (at skin, clothing etc)
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When not on drug, stimulant addicts...
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exhibit many of the motor symptoms of ADHD
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When on drug, stimulant addicts....
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can “get stuck” in behavioral patterns (re-arranging, skin-picking, etc; almost autistic-like)
(sensitization of dopamine?) |
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Certain types of schizophrenia are associated with...
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hyperactivity and involuntary motor movements
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What is the treatment for schizophrenia?
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block dopamine receptors to prevent excessive dopamine from hyper-activating the striatum
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What receptors do anti-psychotic drugs block?
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D2 dopamine receptors
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Tourette’s Syndrome is characterized by...
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motor and verbal tics (involuntary movements
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What is treatment for tourette's syndrome?
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block D2 dopamine receptors
(in fact, treat with antipsychotic drugs) |
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Hypo-activation of the nigro-striatal dopamine pathway causes...
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a variety of motor disturbances
-Type of motor disturbance depends on whether the SN or the striatum is affected |
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What is Huntington’s Disease?
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genetic disorder characterized by
ballismus, hyperactivity, inability to control motor movements produced by a loss of striatal interneurons |
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What are striatal interneurons?
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GABA neurons that go to rest of basal ganglia
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What does reduction in GABA output from the striatum cause?
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enhancement of excitation (glutamate) of the motor cortices -> ballistic movements -> Huntington’s Disease
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What is Parkinson’s Disease?
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characterized by inability to initiate
or terminate a movement, resting tremors, shuffling, loss of fine-motor control |
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What causes Parkinson's disease?
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selective loss of SN dopamine neurons
-low dopamine in striatum -> motor problems |
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What does a reduction in nigro-striatal dopamine pathway cause?
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reduction in excitation (glutamate) of the motor cortices -> reduction in motor control -> Parkinson’s
Disease |
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There are 2 pathways in the basal ganglia out of the....
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striatum
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Loss of striatum=
Loss of SN= |
Huntington’s=hyper-movement
Parkinson’s=hypo-movement |
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What happens if someone overdoses with anti-psychotics?
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Anti-psychotic drugs block the effects of dopamine in the striatum -> shutting down effect of dopamine in striatum -> turn a schizophrenic into a patient with Parkinson’s-like symptom
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What does MTPT do?
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-supposed to be a synthetic
heroin -> teenagers and young adults showing up in the ER with “Parkinson’s” -MPTP turned out to be a neurotoxin for dopamine neurons (killing of both the VTA and SN) |
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How to elevate SN dopamine signals to treat parkinsons....
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-L-DOPA crosses the blood-brain barrier and becomes converted into
dopamine in the brain. Currently a major therapy but lasts only as long as you have dopamine neurons to convert it. -Give stimulants like amphetamine that release dopamine (only works so long as there are enough dopamine neurons) -Activate dopamine receptors directly with drugs that cross the blood-brain barrier (apomorphine; current therapy) |
