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Drugs And Behaviour > Drugs And The Brain > Flashcards

Drugs And The Brain Flashcards

1
Q

Medulla

A
  • controls many biological functions
    • HR, respiration
  • contains area postrema (vomiting centre) with reduced BBB that initiates vomiting in response to toxins in blood
    • helps survival
  • opioid receptors in the medulla involved in lethal overdose
    • respiration shuts down
    • no cannabinoid receptors
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2
Q

Serotonin

A
  • produced in medulla and mid-brain in raphe nuclei
  • receptors found throughout brain and involved in regulating number of processes including sleep, impulsivity, mood, aggression
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3
Q

Locus coeruleus

A
  • principle source for production of NE
  • involved in arousal, attention, vigilance, stress
  • located in pons
  • stimulant drugs: cocaine, amphetamines increase NE/arousal/attention
  • projects through rest of brain
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4
Q

Dopamine

A
  • produced in VTA and substantia niagra
  • located in midbrain
  • part of mesolimbic pathway (nucleus accumbens)
  • part of mesolimbic pathway (prefrontal cortex)
  • part of migrostriatal pathway (striatum)
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5
Q

Essential AAs

A
  • cannot be produced by body
  • must be derived from diet
  • eg. Phenylalanine
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6
Q

Non-essential AAs

A
  • can be produced by the body
  • not required as part of the diet
  • eg. Glutamate
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7
Q

Conditionally non-essential AAs

A
  • can be produced by the body but at rates lower than certain conditions require
  • or require the presence of other AAs to be produced

-eg. Tyrosine

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8
Q

Striatum

A
  • ventral
    • nucleus accumbens
    • globus pallidus
    • reward
  • dorsal
    • caudate
    • putamen
    • motor control
    • habit formation
  • thalamus
    • sensory
    • incoming info sent to other regions

-pathways are altered after addiction

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9
Q

Acute action of drugs of abuse on VTA and NA

A

-various drugs have different effects on DA, GABA and opioid peptides which each affect VTA and NAc

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10
Q

limbic system

A
  • emotional control centre
  • includes
    • amygdala
    • hippocampus
    • hypothalamus
    • nucleus accumbens
  • where production of emotion starts
  • memories/motivating different types of survival related behaviour
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11
Q

Amygdala

A
  • memory consolidation for emotionally arousing events (positive and negative)
  • assigning a reward value to stimuli and in affective conditioning to novel stimuli
    • rodents favouring a specific cage that is identified with a drug will lose this conditioning if the amygdala is damaged
  • exposure therapy essentially retrains the amygdala
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12
Q

Hippocampus

A
  • critical for acquisition of new factual information and formation of episodic memory
  • hippocampus has been implicated in loss of memory in Alzheimer’s
  • damage to hippocampus results in anterograde amnesia (HM)
    • cant form new memories
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13
Q

Bed nucleus of the striata terminalis

A
  • BNST
  • involved in autonomic and behavioural reactions to fearful and noxious stimuli (including stress response)
    • production of negative emotional state
  • considered to be part of the extended amygdala/limbic system
  • involved in stress related/withdrawal related drug seeking
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14
Q

Hypothalamus

A
  • located in the base of the brain
    • near pituitary gland
  • plays role in many functions
    • releasing hormones
    • maintaining daily physiological cycles
    • controlling appetite
    • managing sexual behaviour
    • regulating emotional responses
    • regulating body temp
  • stress causes relapse for most drug addictions because of the drug impact on hypothalamus
    • stress also controlled by HPA axis
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15
Q

HPA axis

A
  • CRH involved in body’s response to physical and emotional stress
    • released by hypothalamus
  • signals pituitary to produce ACTH
  • ACTH triggers production of cortisol from adrenal cortex
  • cortisol feedback to hypothalamus and anterior pituitary to reduced stress producing hormones
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16
Q

Insula

A
  • insular cortex receives visceral, olfactory, gustatory, and other somatosensory inputs
  • involved in relating interoceptive signals to brain regions involved in the appraisal of motivationally relevant stimuli
  • involved in planning and evaluating of goal directed behaviour
    • brings to conscious awareness
  • posterior insula believed to be responsible for coding and processing sensory and interoceptive inputs
  • anterior insula thought to determine how such inputs impact homeostasis
  • strokes that cause anterior insula damage in smokers stopped cravings/withdrawals
17
Q

Anterior cingulate cortex

A
  • interconnected to insula
  • implicated in emotional self control, focused problem solving, error detection, performance monitoring, and adaptive response to changing conditions
  • plays role in planning and evaluation of goal directed behaviour
  • influenced by motivation and affective state
  • calculate best corse of action in any circumstance
18
Q

Prefrontal cortex

A
  • DLPFC
    • implicated in holding/maintaining several pieces of information (working memory)
    • control of cognitive activities
    • planning and selection of goals
  • VMPFC
    • connections to hippocampus and Cingulate cortex
    • assessing the rightness of situation
    • integrating outcome expectancies
    • drug related expectancy effects
  • OFC
    • involved in situations that are unpredictable or uncertain
    • modulated reinforcement value of stimuli in the context of recent experience
    • assesses and decodes the likely value of availability choices of action
    • suppression of previously rewarded responses and requires to change behaviour (ie. STOP signals)
19
Q

How do drugs impact neural communication

A
  • mostly act on NS by interacting with neurotransmission
  • may act on receptor sites (agonism)
  • may block receptor (antagonism)
  • may decrease activity of enzymes that destroy transmitter
  • may block reuptake mechanisms
  • may alter rate of release of NT
20
Q

Biogenic amines (monogamies)

A
  • catecholamines
    • NE
    • DA
    • Epi
  • indoleamine
    • 5-HT
21
Q

Amino acid NTs

A
  • GABA
  • Glutamate
  • glycine
  • proline
22
Q

Peptide NTs

A
  • substance P
  • vasopressin
  • growth hormone
  • prolactin
  • CRH
  • opiate like transmitters
    • enkephalins
    • endorphins
23
Q

Glutamate

A
  • used to help make proteins
  • most abundant AA in brain
  • excitatory actions
  • all neurons contain glutamate for protein synthesis
    • only some use it as a transmitter
  • receptor subtypes: AMPA, kainare, NMDA
  • involved in long term potentiation
24
Q

GABA

A
  • inhibitory transmitter
  • synthesized from glutamate via glutamic acid decarboxylase
  • GABA-A and GABA-B receptors
    • GABA-A most common
  • GABAergic neurons throughout brain including cerebral cortex, striatum, hippocampus
  • effects of GABA enhanced by CNS depressants
    • alcohol, barbiturates, benzos
  • anxiolytics, anticonvulsants, sedative effects
    • could increase overdose risk of GABA
25
Q

Opioid type peptides

A
  • enkephalins (5 AAs)
  • endorphins (16-30AAs)
  • receptor subtypes
    • Mu (analgesic/pleasurable effects)
    • kappa
    • delta
26
Q

Hedonic effects of NTs

A
  • positive (increase)
    • DA
    • opioid peptides
    • serotonin
    • GABA
  • negative (decrease)
    • DA (dysphoria)
    • opioid peptides (pain)
    • serotonin (dysphoria)
    • GABA (anxiety/panic attacks)
27
Q

Anti-reward transmitters implicated in motivational effects of drugs of abuse

A
  • increase dynorphin (dysphoria)
  • increase CRH (stress)
  • increase NE (stress)

-withdrawal increases extracellular levels of CRH

28
Q

PET

A
  • positron emission tomography
  • positron=the antiparticle of an electron
  • emission=release or discharge of a substance into environment
  • tomography=detailed pictures of areas in body
  • PET scanning produces a detailed look at inside of brain through emission of a positron
  • uses radioactive isotopes that decay rapidly
    • during radioactive decay, positron emitted from nucleus
  • if a stable carbon atom is replaced with an unstable carbon isotope, the resulting radiotracer decays by emitting a positron
29
Q

PET continued

A
  • positron-electron annihilation = gamma rays
  • gamma rays are emitted from brain at 180 degrees
  • gamma rays hit scintillator crystals which weight up
  • info transmitted to a computer and origin of positron can be plotted
30
Q

Using PET in psychopharmacology

A
  • directly measure brain distribution and activity of a wide variety of drug classes
    • where do they go in the brain and how to do they act
  • determine drug receptor densities in various regions and keep track of changes that occur with various degrees of drug use
    • how extensive are receptors for various drugs and how quickly do they change with drug use
  • assess competition between radiotracers and NTs or drugs that occupy same receptor site
    • what % of receptor sites need to be activated to produce certain feelings
  • isolate areas of the brain that are active during mental activities such as cravings
    • measure metabolic activity using radioactive glucose and water
31
Q

Using PET to measure tobacco related to DA effects

A
  • condition 1: subjects smoked their usual bran while in scanner
  • condition 2: didnt smoke
  • subjects verbally rated hedonic properties and level of craving
  • increase DA in caudate of C2
  • increase DA in posterior putamen of C2
  • increase DA n anterior putamen of C2
  • increase DA in both conditions in ventral striatum
32
Q

Problems with PET

A
  • low degree of spatial resolution
  • radioactive agents used in patients body
    • 1 PET = 70 chest X-rays
  • expensive because radiotracers decay so quickly that they must be made on site in a cyclotron ($5mil)
33
Q

MRI

A
  • high resolution images constructed from measurement of waves they hydrogen atoms emit in magnetic fields when activated by radio frequency waves
  • fMRI images represent increase O2 flow in blood to active areas in brain
    • oxygenated blood has magnetic properties due to iron in blood
  • signal recorded is called a BOLD (blood oxygen dependent signal )
34
Q

FMRI

A
  • advantages
    • nothing needs to be injected
    • less expensive
    • proved structural and functional info
    • better spatial resolution than PET
  • disadvantages
    • reasons for BOLD changes cannot be determined
    • generation of images takes 2-3 seconds which is too slow to capture many neural events

Drugs And Behaviour (6 decks)

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