goal directed behaviour Flashcards
what do biological rewards do
motivate behaviour
what is the dopaminergic system
the neurons that make dopamine
where is the dopaminergic system
ventral midbrain, specifically :
substantia nigra
ventral tegmental area
substantia nigra function
movement control and initiation
ventral tegmental area function
reward, novelty, motivation
the substantia nigra and vta in the ventral midbrain lead to 3 pathways. what are these?
nigrostriatal pathway
ventral striatum
prefrontal cortex
where is nigrostratial pathway
from substantia nigra, into dorsal striatum
where is ventral striatum
in mesolimbic pathway, from ventral tegmental area
ventral tegmental area/ mesolimbic pathway is part of…
midbrain
ventral tegmental area/ mesolimbic pathway projects to __ in __ via __
ventral striatum in nucleus accumbens via medial forebrain budle
vta, medial forebrain bundle, and nucleus accumbens - where is dopamine released?
cell bodies in vta
dopamine released in nucleus accumbens
what is the mesolimbic dopamine pathway
cell bodies in vta
travel via medial forebrain bundle
dopamine released in nucleus accumbens
what is the mesocortical pathway
cell bodies in vta
travel via medial forebrain bundle
dopamine released in prefrontal cortex
what is intracranial self stimulation
short circuiting reward
intracranial self stimulation rodent study
stimulating electrodes placed in medial forebrain bundle
activated when rat presses lever
press level = stimulate medial forebrain bundle
once learned, rats did not stop and deprioritised other behaviours
similar findings in humans too which is brazy, increased activity but purely of pressing lever
pavlovian classical conditioning
hungry dawg
bell neutral stimulus
neutral stimulus dog food given alongside, became conditioned stimulus
salivating = conditioned response
what is the technical term for what the mesolimbic dopamine neurons do
encode reward prediction error
what is the reward/motivation circuit
rewards stimulate release of DA
unexpected rewards most potent
more rewards = more DA
DA acts as learning signal, learn abt environmental cues that lead to reward. if reward not obtained, DA neurons inhibited
motivation to obtain rewards
substantia nigra and parkinsons disease
pd is death of substantia nigra
thus substantial movement problems
what is substantia nigra dopamine important for - 3
movement initiation
movement termination
smooth movements
no substantia nigra means what - 3
being stiff, rigid, frozen
resting tremor
restless leg syndrome (but this can occur without PD)
how to treat parkinsons disease
put DA back into system via dopamine agonist or dopamine precursors - these act all over the brain
replacing lost DA
what is levadopa
DA, frontline treatment for pd and/or restless leg syndrome
what is ropinrole
DA receptor agonist, frontline treatment for pd and/or restless leg syndrome
issue with treatments for pd
not selective so DA inc all over brain
mesolimbic system may get overstimulated causing compulsive behaviours e.g. compulsive gambling, hypersexuality, binge eating
how are dopamine neurons activated
in the mesolimbic system
what makes u feel good
endogenous opioids
what are endogenous opioids
peptide neuromodulators
how many types of endo opioids are there
3
what are the 3 types of endo opioids
endorphins
enkephalins
dynorphins
what are endorphins important for
reward and motivation
endogenous analgesia
morphine, codeine, heroin, etc mimick what
endorphins
what are endo opioids synthesised as
propeptides
what are neuromodulators
regulate release of other neurotransmitters
what can inhibit tonic DA firing and how do endorphins change this
tonic GABAergic interruptions
endorphins inhibit GABA release from interneurons
thus dec inhibition of DA neurons = more DA
role of GABA
control , prefrontal cortex
works alongside vta impulse function
what is executive function
long term planning
withholding impulsive behaviour
cognitive control
where is executive function
prefrontal cortex
executive function is impaired in
addicts
impaired executive function probs not caused by drug use
they know there is a problem but cannot control own behaviour
where is the prefrontal cortex
rostral to primary motor cortex
executive function requires what region
prefrontal cortex
what can prefrontal cortex do
imagine things without having seen them
working memory
abstract reasoning
high order, flexible decision making
executive functioning
two regions of prefrontal cortex and function
dorsal - thoughts and attention
ventral - emotion
when does prefrontal cortex fully develop - fully myelinate
late 20-30
symptoms of frontal cortex damage
difficulty planning sequence needed to complete task
loss of spontaneous interactions
loss of flexibility in thought
perseveration - persistence of single thought or action
inability to focus on one task
emotional lability
abulia
socially inappropriate behaviour
personality change
difficulty problem solving
excessive aphasia
hemiplegia
(all very humanly, high order complex functions)
what brodmann areas is dorsolateral prefrontal cortex
46 and probs 9
dorsolateral prefrontal cortex roles
working memory
abstract reasoning
topdown regulation of attention
projects to hippocampus
encodes long term memory
more rostral = more abstract
where does morality live
rostral part of dorsolateral prefrontal cortex
ventromedial prefrontal cortex - which broddman area
25
ventromedial prefrontal cortex role
regulation of emotion
represent reward and punishment, consideration of them
calculating value of something
output to limbic system then autonomic (pain)
what is delay gratification
hiding reward, distracting
ability to delay gratification at age 4 predicts future
e.g. educational performance, parental evaluation of success, alevel scores, bmi, use of cocaine, performance on similar task testing control at age40
alternate explanations to stanford marshmallow test - 4
trust
predictability
salience/ hunger
unstable home environments
what does the stroop task test
cognitive control, activation of dorsolateral prefrontal cortex
anterior cingulate cortex
may be activated as part of cog control
looks for errors and mismatches, communicates to dorsolateral prefrontal cortex
anterior cingulate cortex brodmann areas
24, 33, 32
prefrontal cortex is sensitive and impaired by to what
stress
what is stress mediated by (3) and results in what
inc catecholamine release, esp noradrenaline
fatigue
alcohol
results in poor decision making
