2 - Brain Flashcards

1
Q

striatolimbic reward circuit

A
  • main target for drugs of abuse
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2
Q

reward circuit

A
  • controls hedonic tone, attention, expectancy of reward, disconformation of reward expectancy and incentive motivation
  • reinforces survival behaviours (feeding, drinking, sex, social interactions)
  • drugs hijack this circuit and elevate pleasure and reward
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3
Q

hedonic tone

A

trait underlying an individual’s ability to feel pleasure

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4
Q

reward circuit pathway

A
  1. descending myelinated pathway from anterior bed nuclei to ventral tegmental area (VTA) pathway
  2. ascending dopaminergic ventral tegmental area (VTA) to nucleus accumbens (NAc) pathway (feels euphoric)
  3. GABA/subtance P/enkephalinergic nucleus accumbens (NAc) to ventral pallidium pathway
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5
Q

drugs in nucleus accumbens (NAc)

A
  • all addictive drugs increase dopamine levels in NAc

- different drugs will activate reward at different sites

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6
Q

drugs in NAc examples

A
  • cocaine, amphetamine, ecstasy will interfere with dopamine re-uptake in the NAc
  • leads to dopamine release
  • nicotine will depolarize VTA dopaminergic neurons
  • leads to release of dopamine downstream
  • opioids, GHB, benzos, cannabinoids hyperpolarize VTA GABAergic interneurons
  • leads to neuron firing more often, therefore dopamine is released more often
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7
Q

nucleus accumbens (NAc) location

A

basal forebrain striatum

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8
Q

nucleus accumbens (NAc) function

A

-pleasure centre

  • motivation
  • cognitive processing of aversion
  • reward/reinforcement of drug taking
  • translating of emotional stimulus into behaviour and action
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9
Q

nucleus accumbens (NAc) projections

A
  • reciprocal projections with VTA, PFC, amy, hippo, BG

- pleasure, planning, and inhibition of behaviour via PFC, brainstem, BG projections

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10
Q

ventral tegmental area (VA) location

A

midbrain

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11
Q

ventral tegmental area (VA) function

A
  • cognition
  • motivation
  • locomotion
  • main driver of rewarding feelings
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12
Q

ventral tegmental area (VA) projections

A

reciprocal projections with NAc, amy, RN, PFC, BG, etc.

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13
Q

prefrontal cortex (PFC) location

A

frontal lobe but extends into medial regions

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14
Q

prefrontal cortex (PFC) function

A
  • self-awareness
  • planning
  • problem solving
  • leaning
  • memory
  • executive function
  • personality
  • decision making
  • social behaviour
  • dysfunction linked with mental conditions
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15
Q

prefrontal cortex (PFC) projections

A
  • projections to VTA and amy expression of behaviours trained by chronic drug abuse
  • reciprocal connections with multiple regions involved with attention, action, and cognition
  • integrated in multiple regions
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16
Q

hippocampus location

A

para-saggital plane, behind amy

17
Q

hippocampus function

A
  • memory formation
  • processing nove/contextual info
  • neuronal stem cells suppressed by drugs (affects long-term memory)
18
Q

hippocampus projections

A

VTA that modulate plasticity and learning/memory

19
Q

amygdala function

A
  • emotions (most disabling symptom in addicts)
  • learning/memory
  • reward
  • attention
  • associate cues with drug consumption, conditioning, and reinstatement
20
Q

amygdala projections

A

disrupted connection with VTA with drug abuse (amy permits emotional regulation, PFC is in charge of decision making)

21
Q

caudate nucleus (CN) function

A
  • voluntary movement
  • learning
  • memory
  • sleep
  • pain
  • social behaviour
  • drug accumulation due to the ability to bind transporters
22
Q

caudate nucleus (CN) projections

A
  • VTA, NAc, hippo, amy

- lesions alter chronic effects

23
Q

locus coeruleus (LC) location

A

dorsal pons (in front of cerebellum)

24
Q

locus coeruleus (LC) function

A
  • arousal
  • cognition/memory
  • sleep/wake
  • attention
  • emotion
  • stress
  • regulates withdrawal symptoms
25
locus coeruleus (LC) projections
- VTA, brainstem, cerebellum, thalamus, hypoth, hippo, amy, BG, cortex, spine - LC and norepinephrine afferents are modulated by kappa opioid receptor activation
26
raphe nuclei (RN) location
dorsal medulla oblongata, and multiple nuclei
27
raphe nuclei (RN) function
regulate mood, emotion, aggression, sleep, anxiety, memory, appetite, pain, and temp.
28
raphe nuclei (RN) projections
- hypoth, limbic system, brainstem, spine - nuclei and forebrain projections are targets of alcohol, opioids, MDMA, etc. - RN to PFC projections have shown that RN is linked in neuropsychiatric disorders (OCD, ADHD, schizo)
29
VTA to NAc
dopaminergic projections are the core of the reward circuit
30
euphoria in drugs
lost in time bc of the removal of receptors
31
PFC inputs
core of anticipation circuits
32
amy inputs
core of reinstatement/relapse circuits
33
reinstatement vs relapse
- reinstatement is drug-seeking behaviour | - relapse is returning to drug taking
34
neuroplasicity
ability of the brain to form new connection, change wiring patterns and establish new pathways
35
action potential
nerve fires (transmitters released) as dendrites or soma reach their threshold
36
repeated firing
long-term changes will occur due to molecular signalling and transcriptional changes
37
goal-directed circuits
- occasional recreational use to impulsive use to habitual compulsive use - reward-driven changes to goal-driven drug-seeking behaviour - ventral striatum-to-dorsal striatum-mediated shift in control of-drug-seeking behaviour
38
dependance and addiction
- not the same, but highly related - many drugs induce dependence without addiction - dependance is triggered by tolerance/withdrawl - addiction is triggered by reward circuit activation