L48 - Limbic system and central autonomic function

Question 1

<p>List some primary and secondary emotions</p>

Answer 1

<p>Primary (reflexive) : Fear, anger, surprise, disgust, happiness, sadness.

Secondary (cognitive) : Envy, shame, guilt, etc.</p>

Question 2

<p>What modulates emotions and drive motivated bahaviors?</p>

Answer 2

<p>Rewards, both good and bad</p>

Question 3

<p>List general brain regions involved in the limbic system.</p>

Answer 3

Prefrontal and association cortex

Cingulate gyrus

Hippocampal formation

Mamillary body of hypothalamus & Hypothalamus

Anterior nucleus of Thalamus

Amygdala

Question 4

<p>Function of the limbic system?</p>

Answer 4

<p>integrate information about sensory stimuli, memories, and cognitive plans

>> produce emotional learning and experience</p>

> > modulate emotional responses

Question 5

Role of the hypothalamus in the limbic system?

Answer 5

 Modulate autonomic output in emotional responses

 Generation of aggressive behavior patterns **

Question 6

Describe the connection between neocortex and hippocampus?

Answer 6

<p>Via Entorhinal area</p>

Question 7

Describe the brain regions involved in the Papezcircuit?

Answer 7

Hippocampal formation 
>> fornix (connect temporal lobe to diencephalon)
>> Mamillary body of hypothalamus 
>> Mammilothalamic tract 
>> Anterior nucleus of thalamus
>> Cingulate gyrus 
>> Cingulum (tract)
>> Entorhinal cortex
>> Hippocampal formation

Question 8

Role of Amygdala in the limbic system?

Answer 8

1) Key coordinator: Linking cortical processing to the hypothalamus and other subcortical brain structures
2) expression of fear, anxiety, stress
3) Response to emotional facial expression + emotional arousal

Question 9

List some functions of primary reflexive emotions?

Answer 9

Aid survival:

• Fear = danger, fleeing, fast escape
• Anger = fight
• Surprise = response to novel stimuli and prepare for reaction
• Disgust = avoid poisoning, infection (limbic system connected to olfactory bulb)
• Joy = motivator, drive

Question 10

Changes in behavior due to amygdala damage? ( Kluver-Bucy syndrome )

Answer 10

• Tame, loss of fear, blunted emotions, less aggression
• Forget rapidly
• Increase oral activity and sexual behavior

Question 11

Describe the 2 neural pathways for processing emotional stimulus into emotional response?

Answer 11

For evaluating emotions, long-term memory:
- Central/ Indirect pathway: Thalamus > Cortex > Amygdala > descending efferent output

For autonomic responses:
- Peripheral/ Direct pathway: Thalamus > Amygdala > descending efferent output

Question 12

List some autonomic responses triggered by the posterior** hypothalamus after emotional stimuli?

Answer 12

• Sympathetic- like responses:
  Increase BP, shivering
  GI stimulation: hunger and thirst, feeding reflexes
  Rage

Question 13

List some autonomic responses triggered by the anterior** hypothalamus after emotional stimuli?

Answer 13

Parasympathetic-like response:

• Oxytocin release
• Decrease BP, HR
• Bladder contraction
• Panting, sweating

Question 14

Which brain region is responsible for eliciting hunger, thirst and feeling of fullness (satiety)?

Answer 14

Lateral hypothalamus: feeding/ hunger center

Question 15

Consequences of lateral hypothalamus lesion?

Lesion in Ventromedial hypothalamus?

Answer 15

Lesions in lateral hypothalamus (feeding / hunger center) :

• Hypophagia (decrease in food intake) / aphagia (lack of eating)
• Adipsia (absence of thirst)

Lesions of ventromedial hypothalamus (satiety center) = loss of satiety

Question 16

Describe the output of the amygdala for modulating autonomic emotional expression/ response?

Answer 16

2 tracts to reach branstem nuclei:

1) Indirect: Central nucleus in amygdala&raquo_space; Hypothalamus (medial and lateral)&raquo_space; Brainstem nuclei
2) Direct: Central nucleus in amygdala&raquo_space; brain stem nuclei

Both tracts output to modulate sympathetic and parasym. neurons = change emotional response

Question 17

Which sensory input can directly impact the autonomic output of the amygdala for emotional response?

Answer 17

1) visceral organs and taste** receptors&raquo_space; solitary nucleus&raquo_space; brain stem
2) Olfactory system > directly to amygdala > brain stem

Modulate emotional response through changing sympathetic and parasym. output

Question 18

Which brain region is associated with euphoria and pleasant sensations?

Answer 18

Septal region: pleasure centre

Closely connected with the dopaminergic limbic system

Question 19

Describe the sequence of structures in the mesolimbic pathway.

Answer 19

mesolimbic pathway:

septal area&raquo_space; dopaminergic connection» ventral tegmental area**&raquo_space; Nucleus accumbens

(Pathway through lat. hypothalamus to reach frontal cortex is mesocortical pathway)

Question 20

Which brain region is associated with reward and addiction?** (not euphoria/ pleasure)

Answer 20

Nucleus accumbens

Question 21

Which brain area forms most of the mesolimbic system?

Answer 21

Ventral tegmental area

mesolimbic and mesocortical projections involved in reward by dopamine release

Question 22

Describe the autonomic output when fear stimuli activates the amygdala (corticomedial area)?

Answer 22

Amygdala: indirect or direct output to brainstem, trigger sympathetic activation (fight-or-flight response):

 Tachycardia 
 Sweating
 Paleness 
 Pupil dilation 
 Piloerection  
 Adrenal release of adrenaline

Question 23

How is the olfactory system connected to the limbic system?

Answer 23

Olfactory system > Medial amygdala group > hypothalamus

Question 24

What is the role of the Ventral Tegmental area? What emotions/behavior does it regulate?

Answer 24

Form most of mesolimbic/ mesocortical pathways: for REWARD ANTICIPATION:

• VTA neurons provide a learning signal that reflects reward expectation
• i.e. seeing reward cause VTA neurons to fire in prediction and anticipation of getting the reward

Question 25

Input and output of the nucleus accumbens?

Answer 25

Input: dopaminergic input from midbrain dopamine neurons (e.g. septal area for euphoria)

Output: hypothalamus and limbic structures mediating emotional responses

Question 26

Which brain region is affected by addictive drugs i.e. Cocaine and amphetamines? explain the physiological effects?

Answer 26

Medial Forebrain Bundle that innervates the Ventral Tegmental Area: especially Nucleus Accumbens***:

• increase dopamine release in shell of the nucleus accumbens
• Block dopamine reuptake at synapses
• Enhance dopamine release by acting on presynaptic cholinergic receptors (Nicotine)

> > Enhance pleasure

Question 27

List functions of the Dopamine pathways?

Answer 27

Nigrostriatal, mesolimbic, tuberoinfundibular:

• Reward (motivation)
• Pleasure, euphoria
• Motor function (fine tuning)
• Compulsion
• Perseveration

Question 28

List functions of the serotonin pathways?

Answer 28

• Mood
• Memory processing
• Sleep
• Cognition

Question 29

Define the parasympathetic tracts/ CN nuclei that are modulated to produce emotional responses?

Answer 29

CN 3,8,9,10 + Sacral outflow tracts

Question 30

Which brain area has increased firing activity in the learned anticipation of reward?

Answer 30

VTA

Question 31

What is the function of the VTA in the mesolimbic system?

Answer 31

VTA neurons provide a learning signal that reflects reward expectation

> > guide behavior and to modulate emotional responses to reward-predicting stimuli.

Question 32

Which area in the mesolimbic system uses NE as neurotransmitter?

Answer 32

Locus coeruleus

Question 33

Which area in the mesolimbic system uses Dopamine as neurotransmitter?

Answer 33

VTA, Substantia nigra

Question 34

Which area in the mesolimbic system uses Serotonin as neurotransmitter?

Answer 34

Raphe Nucleus

Question 35

Which area in the mesolimbic system uses Ach as neurotransmitter?

Answer 35

Basal forebrain

Question 36

List the structures that make up the hippocampal formation?

Answer 36

(dentate gyrus, hippocampus, subiculum)