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unu bst > neurotransmitatori 1 > Flashcards

neurotransmitatori 1 Flashcards

1
Q

what are neurotransmitters

A

chemicals that allow the communication between cells

releasing cell - neurone
target cell - neurone, gland cell or muscle cell

they have excitatory or inhibitory effect

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2
Q

why are NT important

A

important for activities that regulate our behaviour, cognition and emotions

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3
Q

where are NT stored

A

nt are contained in synaptic vesicles in the pre synaptic neurone

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4
Q

where are NT released

A

following action potential they are released into the synaptic cleft which is a small space between neurone and target cell

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5
Q

how do they reach the target cell

A

the act by binding onto the receptor of the post synaptic cell

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6
Q

summarise the action of a nT

A

in response to an action potential, NT is released at pre-synaptic terminal

NT moves across the synapse and binds with receptors in the post synaptic neurone, causing change in the membrane potential

Binding of NT may influence the post synaptic neurone in either an inhibitory or excitatory way

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7
Q

what is an excitatory action

A

contributes to trigger an action potential

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8
Q

what is an inhibitory signal

A

action that prevents action potential

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9
Q

why does a NT need to be stopped

A

bc it might become inappropriate or too time consuming

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10
Q

what are the four mechanisms a NT can be stopped

A

Diffusion
Enzymatic degradation
Glial cells
Reuptake

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11
Q

what is diffusion

A

when a NT moves away from the synaptic cleft where it can no longer act on a receptor

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12
Q

what is enzymatic degradation

A

then NT change their chemical structure by the action of enzymes so that they are no longer recognised by the receptors on the post synaptic cell and can no longer exert action

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13
Q

what is the mechanism of glial cells

A

NT can be moved away from the synaptic cell by glia cells

astrocytes remove NT from the synaptic cleft

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14
Q

what is re-uptake

A

recycling on NT
taking NT that has not been used back from the synaptic cleft
back into the presynaptic cell

nT is taken by a transporter

re-uptaking or failing to re-uptake is the basis of certain pathologies and addiction

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15
Q

summary of nT

A

production of NT which occurs in the cell body, the axon or the axon terminal

NT are stores in vesicles in the axon terminal

then released in synaptic cleft following an action potential

bind to receptors on post synaptic cell

NT is deactivated by diffusion, change due to action of enzyme, or re-uptaken into the pre-synaptic neurone

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16
Q

why do we focus on NT that are dominant

A

we look at NT that is more strongly present at the axon terminal

then a neurone and its dominant NT can be related to a function or behaviour

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17
Q

what are the 4 main NT systems in the central nervous system

A

dopaminergic system - dopamine

serotonergic system - serotonin

noradrenergic system - noradrenaline

cholinergic system - acetylcholine

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18
Q

what is the dopaminergic system

A

dopamine is produced in nerve cells mainly originating in the midbrain - substantial nigra and ventral tegmental areas VTA

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19
Q

where do neurones in subtantia nigra and VTA send their axons ?

A

from the substantial nigra and VTA, the system branches in 3 different directions that represent 3 different circuits

mesocortical
nigrostriatal
mesolimbic

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20
Q

what is the mesocortical system

A

starting from VTA across the cortex

important for cognition, memory, attention, emotional behaviour, learning

21
Q

what is migrostriatal system

A

VTA to subcortical areas
important in movement, sensory information

Parkinson’s disease characterised by difficulty in movement due to malfunctioning of dopamine in this circuit

22
Q

what is the mesolimbic system

A

from VTA to areas of the brain that deal with emotional stimuli and important for processing of reward, pleasure, seeking behaviours, addiction, emotion, perception

23
Q

what is the role of dopamine in reward

A

dopa is important in maintaining and processing stimuli that generate sense of pleasure and reward

reward is associated with certain activities that are important for survival

bc of the importance of these functions, its critical to have sense of pleasure associated with them so that we are more inclined to look for these stimuli

24
Q

what is study on how dopamine is important for survival

A

dopamine levels increase when animals or humans are exposed to survival activities (food or sexual stimulation)

25
Q

how did dopamine levels increase in animals or humans

A

areas of the brain engaged in reward related activities are stimulated electrically resulting in an increase in rewarding effect

lesions to these parts of the brain will result in modification of preferences towards rewarding stimuli

26
Q

what else is reward important for

A

rewarded activities are pleasurable, provide validation, social affirmation and connection

27
Q

what is dopamine’s function as a predictor of reward

A

it is important to have a system in place that allow us to be engaged in activities that are likely to result in a sense of pleasure

we need to anticipate when a certain activity is likely to be linked to reward

2 distinct components to reward processing:
1. consumatory component
2. anticipatory component

28
Q

what is the consumatory component

A

when we receive a reward

29
Q

what is anticipatory component

A

activities we engage with based on past experiences we are likely to expect a reward that is not yet present

30
Q

what are the different areas associated with reward vs reward anticipation

A

reward - greater activation of areas such as insula and frontal operculum SO frontal part of the brain

reward anticipation - greater activation of areas like amygdala, hypothalamus, striatum

31
Q

why is reward important for learning

A

The skill to predict an award is important bc it’s important for learning

learning occurs when actual outcome is different from predicted outcome, resulting in prediction error

prediction error= failure to anticipate some expected event to occur

learning allows us to adjust future predictions to match the outcome more closely

32
Q

how does the brain detect prediction mistakes

A

dopamine is released when predictions errors are made

this is shown in increased activity in striatum

in SZ there is inability to make predictions- and SZ patients have problems with dopamine

33
Q

what is random reward

A

random rewards keep individuals responding for longer and repeatedly

this is why u stay in a rship when the person responds randomly

34
Q

what is dopamine and memory

A

the hippocampus encodes memories for new events or episodes

hippocampal activity corresponds to dopamine released to keep memory of new events

35
Q

what is a study to test the role of dopamine in memory

A

it is possible to improve duration of episodic memory by manipulating dopamine artificially

ppts took dopamine 1h and a half before experiment

low
medium
high dosage

looked at images in fMRI scanner

imaged depicted indoor or outdoor scenes

half images associated with reward, half not

then 1 hour or 3 hours after they were presented with same images mixed up with new images and indicate if they seen image before or not

RESULTS
performance improved especially for those who received dopamine in the middle dosage

hippocampus more activated for remembered than forgotten items

so dopamine is critical for episodic memory consolidation

36
Q

what is the serotonergic system

A

based on serotonin- feel good chemical

regulates: sleep, appetite, mood balance, social behaviour, inhibition

37
Q

what happens when serotonin is downregulated

A

depression, aggression, over-eating, suicide , SZ

38
Q

What is the role of serotonin in moral judgement

A

moral judgement - certain behaviours aren’t morally appropriate

serotonin is a key player in this ability

39
Q

what are the 2 hypothesis of how to test the role of serotonin in moral judgment

A

harm aversion

emotion regulation

40
Q

what is harm aversion

A

serotonin controls certain impulses
serotonin promotes pro social behaviour and discourages antisocial behaviour

41
Q

what is emotion regulation

A

serotonin promotes the control of violent impulses or down regulation of emotional reactions to provocation

42
Q

how was role of serotonin in moral judgement studies

A

Ppts took a drug or a palcebo

Ppts were either taking a drug that amplified action of serotonin or amplified action of noradrenaline (linked to executive functions)

Drugs acted on re-uptaking
so NT remains available in synaptic cleft and effect of NT can be amplified

ppts addressed issues related to moral dilemmas

RESULTS
ppts found dilemmas that involved personal harm as less acceptable

boosting serotonin made personal situations less plausible than boosting noradrenaline

so serotonin enhances aversive emotional reactions to harm

43
Q

what about serotonin and antisocial behaviour

A

serotonin has been linked to callous unemotional traits:
- lack of shame
- lack of empathy and understanding of other’s feelings
- psychopathic personality

ppts who scored low callous unemotional traits had higher levels of serotonin

so serotonin is linked to cognitive and emotional deficits in people with high levels of CU traits

44
Q

what’s the role of serotonin in impulsivity

A

impulsivity is behaviour that occurs without foresight

serotonin is involved in psychopathology

low serotonin is linked to behavioural disinhibition leading to aggression

45
Q

what is the noradrenergic system

A

adrenaline based

originates in brain stem structures - locus ceruleus and medulla

46
Q

what are the 2 branches of the noradrenergic system

A

from the brainstem:
1. dorsal ascending system - covering neocortex and hippocampus

  1. ventral system - hypothalamus and limbic system - therefore involved in processing emotions
47
Q

what are the main functions of the noradrenergic system

A

arousal
processing novelty
sensation seeking behaviour

too much novelty may cause stress

48
Q

whats the rship between noradrenaline and sensation seeking behaviour

A

high sensation seeking - increased risk of addiction and negative behaviours

ppts divided into high and low sensation seeking behaviour

ppts in fMRI looked at images which could be high (nudity or violence) or low level of arousal (objects or people)

RESULTS
High sensation seeking activated brain areas involved in arousal more than low - especially for stimuli high in arousal

low sensation seekers: activated brain areas involved in emotional regulation - especially for stimuli high in arousal level - so they need to keep this stimuli under control and downregulate the emotions that this stimuli provoked

49
Q

what is the cholinergic system

A

system regulated by acetylcholine

2 branches:
1 covers neocortex and hippocampus - important for a form of arousal called vigilance which has an impact on attention, memory encoding, and working memory processes

1 branch covers brain stem and important for regulation of sleep waking cycle

unu bst (18 decks)

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