Lecture 12- Neuroscience of emotion II

Question 1

What are the dimensional models of emotions?

Answer 1

• two dimensioanl nature of emotions= often come on opposites
• can map emotions in terms of pleasantness and arousal they generate
• all emotions have some significance there is no neutral emotion
• can also map in valence (the context), persistence and intensity

Question 2

What is the second principle of antithesis?

Answer 2

• the basic idea that emotions have opposites
• this principle observed in humans, dogs and drosophila
• first proposed by Darwin

Question 3

What does the fear response depend on?

Answer 3

• how amygdala performs is very context dependent
• the distance of the threat is important, proximal threats produce panic, distal threats produce anxiety
• the inputs and outputs of the amygdala act according to context
• when distal threat= the lateral amygdala and prefrontal cortex engage, cortex is doing the processing of the context
• when the threat is proximal get more engagement of central amygdala and the periaquaductal gray (defense)
• when lateral amygdala engaged the preparation for defense like freezing behaviour

Question 4

What do you get by stimulating rostral and anterior part of the periaquaductal gray?

Answer 4

• rostral= aggressive behaviour, ready for an attack

- anterior= defensive behaviour

Question 5

What is the concept of defensive distance?

Answer 5

• these are studies showing what was on previous slide:

• patients without amygdala do not have avoidance of super close interaction with people

-fMRI study, see spider in mirror, see the pattern of activation
• the distance has an effect on the reaction

Question 6

What is the importance of cue vs context?

Answer 6

• context in which you see a fear stimulus like a snake matters
• snake is the cue, will activate amygdala circuitry
• the cortex and thalamus are crucial in establishing the context in which you see the cue

Question 7

What is the contextual modulation of fear?

Answer 7

• when you teach a rat to associate a context that is previously non threatening to have a fear response
• when put a rat in a cage it is used to= no fear
• pain in the cage= fear, put in a different cage= no fear
• bell and pain= fear, being in the cage= fear, put in a different cage and bell= fear

Question 8

What is contextual retrieval?

Answer 8

-associate bell with fear only in the cage in which it gets shocked

Question 9

What is extinction and context?

Answer 9

• can’t just accumulate associations and memories so must have a process of forgetting and extinguishing memories and associations
• repeat the bell without pain for a long time and eventually get no fear response to the conditioned stimulus= bell
• but we do not forget the memory, the trace is still there allows us access to it when needed

Question 10

What is the context-dependence of neuronal activity in the rat amygdala?

Answer 10

-return of fear in response to an extinguished conditional stimulus is correlated with neuronal firing in response to the conditional stimulus in the amygdala in rats

Question 11

What is the connection between the amygdala and the stress response?

Answer 11

• amygdala activation by repeated, prolonged or unpredictable psychological stimuli induces stress response
• it is regulated by hormonal feedback
• dysregulation is a major cause of clinical syndromes like PTSD

Question 12

What is the stress response?

Answer 12

-when the Paraventricular nucleus stimulated by the central amygdala stimulates the pituitary to release ACTH which goes to the adrenal gland and the cortex of that releases glucocorticoids and medulla releases epi and norepinephrine
=these cause increase in cardiovascular tone, increase in blood pressure, mobilization of stored energy to muscle, transient enhancement of immunity, and inhibition of long-term processes such as growth and reproduction

Question 13

What is the feedback loop of the stress response?

Answer 13

• the glucocorticoids and epi and norepinephrine affect the brain and regulate their own levels
• via vagus and monoamine system

Question 14

What is the model of fear related disorders?

Answer 14

1. pre-existing sensitivity (gene+environment)
2. learning of fear (index traumatic event)
3. Consolidation of fear (hours to days following event)
4. Expression of fear (flashbacks, nightmares, memories, avoidance, sympathetic response, startle)
5. reconsilidation
   - normally diminished response to cues over time and limit fear to specific trauma cue (discrimination)
   - in pathological cases= increased fear with repeated exposure (sensitization) and generalization: recruitment of non-associated cues

Question 15

What is used to drive motor system?

Answer 15

-sensory information is crucial

Question 16

What is the human basal ganglia like?

Answer 16

• part of the striatopallidal system
• also called caudal putament
• contains the putamen, caudate, substantia nigra,globus pallidus internal and external segment

Question 17

What are the hyperdirect and direct pathways in the striatopallidal system?

Answer 17

• cortical input into striatum (from the motor cortex)
• direct to glubus pallidus
• indirect via globus pallidus and via subthalamic nucleus
• striatum also directly projects to the motor pathways
• look at the picture (slide 20)

Question 18

What are the dopamine projections from ventral tegmental area (A10)?

Answer 18

a group of neurons located close to the midline on the floor of the midbrain (mesencephalon). The VTA is the origin of the dopaminergic cell bodies of the mesocorticolimbic dopamine system and is widely implicated in the drug and natural reward circuitry of the brain. It is important in cognition, motivation, orgasm,[2] drug addiction, intense emotions relating to love, and several psychiatric disorders. The VTA contains neurons that project to numerous areas of the brain, from the prefrontal cortex (PFC) to the caudal brainstem and several regions in between.

Question 19

What are the specialised cortico-basal ganglia-thalamocrotical circuits?

Answer 19

• traditionally a motor circuit but also important for emotions
• the limbic part= goes from ACA and MOFC cortex to ventral striatum(in motor goes to putament), then to Substantia nigra reticulata and Glopus pallidus interanal segment and then thalamus= the VAmc, VLm, MD(here the difference to motor)
• thalamus then feeds back to the cortex

Question 20

What does the emotional system do? the limbic one?

Answer 20

• goal directed behaviour: behaviour controlled by representation of a goal or an understanding of a causal relationship between a behaviour and attainment of a foal
• reinforcers: 1. positive reinforcers= rewards S+, increase the frequency of behaviour leading to their acquisition
  2. negative reinforcers= punishers S-, decrease the frequency of behaviour leading to their encounter and increase the frequency of behaviour leading to their avoidance

Question 21

What is the positive reinforcement produced by electrical stimulation of septal area and other regions of the rat brain about?

Answer 21

• how reinforcement is linked to the stratiopallidal system
• the septal area is the pleasure zone in animals, get connections to amygdala etc.
• get orgasmic feeling when stimulate this
• the lever experiment where rat stimulates itslef
• centered around the dopamine pathway

Question 22

What is the reward circuitry?

Answer 22

• ventral tegmental area with its dopaminergic neurons is central
• sends dopaminergic neurons to the nucelus accumbens
• also ventral pallidum is involved and medial prefrontal cortex
• The major neurochemical pathway of the reward system in the brain involves the mesolimbic and mesocortical pathways. Of these pathways, the mesolimbic pathway plays the major role, and goes from the ventral tegmental area (VTA) via the medial forebrain bundle to nucleus accumbens. The VTA is the primary release site for the neurotransmitter dopamine. Dopamine acts on D1-like receptors or D2-like receptors to either stimulate (D1-like) or inhibit (D2-like) the production of cAMP

Question 23

Is dopamine pleasure?

Answer 23

-no
- it is the probability of reward
-the experiment monkey gets food and the dopamine is not linked to the presence of food it is when the signal is given that it will be given
=it is the reward prediction

Question 24

How does neuronal activity change with reward learning?

Answer 24

• when reward is expected the activity of dopamine neurones drops
• only when encountering reward that is not expected are the dopaminergic neurones very active

Question 25

What is the reward processing and the brain? (thalamus)

Answer 25

-thalamus gets info from outside and sends to medial temporal cortex(reward detection and prediction), the dorsolateral prefrontal, premotor and parietal cortex(goal representation) and orbitofrontal cortex(relative reward value, reward expectation)

Question 26

What is the reward processing and the brain? (cortex)

Answer 26

-medial temporal cortex, dorsolateral , prefrontal and premotor and parietal and orbtofrontal all send information to the striatum that sends it to the substantia nigra pars reticulata and globus pallidum and those send to thalamus

Question 27

What is the reward processing and the brain? (amygdala)

Answer 27

-sends to dopamine neurons,striatum, thalamus and orbitofrontal cortex (relative reward value, reward expectation)

Question 28

What is the reward processing and the brain? (dopamine neurons)

Answer 28

• send to amygdala
• striatum
• orbitofrontal cortex
• dorsolateral, prefrontal, premotor, parietal cortex
• mediatemporal cortex

Question 29

What is an innate (unconditioned) trigger? stimulus

Answer 29

like pain, innate response to it without need for prior exposure

Question 30

What is a learned (conditioned) trigger (stimulus)?

Answer 30

associated with innate trigger via pavlovian conditioning

-ellicits innate responses because of the association

Question 31

What is an innate incentive (unconditioned or primary)?

Answer 31

increases approach towards or avoidance of the stimulus in an effort to resolve the challenge or opportunity present

Question 32

What is an incentive?

Answer 32

Modulates instrumental goal directed behaviour to help meet the opportunity or challenge signalled by the stimulus that is triggering activation of a specific survival cicruit

Question 33

What is a learned/conditioned/secondary incentive?

Answer 33

invigorates and guides behaviour towards situations where challenge or opportunity presented can be resolved

Question 34

What is a reinforcer?

Answer 34

supports the learning of pavlovian or instrumental associations

Question 35

What is an innate/unconditioned/primary reinforcer?

Answer 35

induces the formation of associations with neutral stimuli that occur in its presence through pavlovian conditioning, and to the formation of associations with responses that lead to the presentation of an apetitive stimuli or removal of an aversive stimuli.

Question 36

Summary?

Answer 36

look on the last slide