Drugs And The Brain Flashcards
(34 cards)
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
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
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
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)
5
Q
Essential AAs
A
- cannot be produced by body
- must be derived from diet
- eg. Phenylalanine
6
Q
Non-essential AAs
A
- can be produced by the body
- not required as part of the diet
- eg. Glutamate
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
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
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
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
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
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
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
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
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
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
Opioid type peptides
- enkephalins (5 AAs)
- endorphins (16-30AAs)
- receptor subtypes
- Mu (analgesic/pleasurable effects)
- kappa
- delta
26
Hedonic effects of NTs
- positive (increase)
- DA
- opioid peptides
- serotonin
- GABA
- negative (decrease)
- DA (dysphoria)
- opioid peptides (pain)
- serotonin (dysphoria)
- GABA (anxiety/panic attacks)
27
Anti-reward transmitters implicated in motivational effects of drugs of abuse
- increase dynorphin (dysphoria)
- increase CRH (stress)
- increase NE (stress)
-withdrawal increases extracellular levels of CRH
28
PET
- 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
PET continued
- 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
Using PET in psychopharmacology
- 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
Using PET to measure tobacco related to DA effects
- 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
Problems with PET
- 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
MRI
- 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
FMRI
- 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
