ICL 5.0: The Emotional Brain and The Limbic System

Question 1

what is the limbic system?

Answer 1

a collection of anatomically related structures that vary greatly in function but interact/modulate with one another; this presentation will refer to it as a system

it’s a system that contributes to HOME:

Homeostasis
Olfaction
Memory
Emotion

Question 2

what are the 5 F’s of the limbic system?

Answer 2

Fleeing

Fighting

Feeding

Feeling

Fornication

Question 3

how does the limbic system play a role in emotion?

Answer 3

1. remembering past events that were both pleasant and traumatic
2. perceiving threats from our surroundings
3. making choices based on our experiences
4. controlling movements based on past learning
5. form sensory preferences - likes/dislikes

it doesn’t deal with what makes you happy or sad – if you damage the limbic system it doesn’t make you unhappy but it can increase or decrease your hunger, thirst, sex drive, aggression, fear –> so it has an effect on positive vs. negative emotions but not technically your happiness

Question 4

what are the functions of the limbic system?

Answer 4

1. controlling emotions like anger and fear
2. regulating eating, hunger and thirst
3. responding to pain and pleasure
4. controlling functioning of the autonomic nervous system, including things like pulse, blood pressure, breathing and arousal
5. sensing sexual satisfaction
6. controlling aggressive or violent behavior
7. responding to sensory information, especially sense of smell

Question 5

what anatomical structures are part of the limbic system?

Answer 5

1. hypothalamus
2. hippocampus
3. amygdala

then there’s also

4. septal nuclei
5. mammillary bodies
6. cingulate gyrus
7. periaqueductal grey
8. fornix

Question 6

what is the function of the hypothalamus?

Answer 6

1. regulating hormones and maintaining homeostasis –> it feeds information into the limbic system
2. controls vegetative, endocrine functions and aspects of emotional behavior
3. controls internal conditions such as temperature, osmolality, drive to eat and drink, control body weight, sleep, bowel function, bladder activity, sexual performance

Question 7

what is the function of the hippocampus?

Answer 7

1. memory and focus
2. motor control
3. forming short-term and long-term memories through consolidating information
4. learning new skills from reward, punishment, reinforcement and failure with help from the septal nuclei
5. recognition of what’s familiar versus new
6. navigation or sense of direction; spatial memory
7. involved in olfaction (smelling) and tying together smells with specific memories*
8. the hippocampus receives input from and sends output to the amygdala, which plays an important role in the limbic system by creating emotional significance to feelings (positive or negative)

Question 8

what is the function of the amygdala?

Answer 8

1. tied to fear and anxious emotions –> so if there’s damage to the amygdala you won’t have any fear or worry which can actually be bad
   ex. anger black out and panic from anxiety disorder that caused panic and then anger
2. learning and memory of emotional significance of stimuli
3. receives neuronal signals from all parts of the limbic cortex
4. widespread outputs to cortex, hippocampus, hypothalamus and brainstem
5. learns and maintains link between stimulus and its emotional value

Question 9

what is the function of the septal nuclei?

Answer 9

pleasure and learning through reward and punishment –> it’s very involved in operant conditioning!

it’s involved in the affective nature of sensory sensations so whether the sensations are pleasant or unpleasant aka reward or punishment/satisfaction or aversion

Question 10

what is the function of the mammillary bodies?

Answer 10

primary function is recollective memory

this is when an individual recalls a specific episode from their past; it could be positive or negative

very active with PTSD

Question 11

what is the function of the cingulate gyrus?

Answer 11

processing emotions and behavioral regulation

ex. when you come into the lecture hall for a final and you’re anxious, tapping your leg, etc. that’s the cingulate gyrus

Question 12

what is the function of the periaqueductal grey?

Answer 12

anatomic and functional interface between the forebrain and the lower brainstem and has a major role in integrated behavioral responses to internal (e.g., pain) or external (e.g., threat) stressors –> the PAG is what’s responsible for the fight-or-flight response that will either make you freeze or run away from the situation

not always seen as part of the limbic system but has connects to the system, particularly through the hypothalamus

PAG transforms messages about threat to action: with pain it will elevate or reduce the pain signals returned to injured limb and it takes signals of other threats from hypothalamus and initiates the behavioral responses of fight-or-flight

Question 13

what is the function of the fornix?

Answer 13

it’s the major tract out of the hippocampus and it’s associated with memory

Question 14

what structures aren’t officially part of the limbic system but are associated with the septal nuclei?

Answer 14

1. ventral tegmental area

releases dopamine in response to rewarding stimuli – so it’s involved with motivation and conditioned responses

2. nucleus accumbens

plays a role in the analysis of reward and reinforcing information

these two play a huge role in addiction

Question 15

what is the Papez circuit?

Answer 15

an anatomical circuit within the limbic system that starts and ends in the hippocampus.

it helps modulate learning and emotional expressions such as sexual desire, pleasure, fear, and anxiety

so it controls emotional expression!!

Question 16

which structures are involved in the Papez circuit?

Answer 16

hippocampus → fornix → mammillary bodies (hypothalamus) → via the mammillothalamic tract → anterior thalamic nucleus → cingulate gyrus → cingulum → hippocampus

slide 10-12

Question 17

how do drugs effect the limbic system?

Answer 17

drugs of abuse highjack limbic circuits responsible for processing pleasure and reward

this would include the nucleus accumbens and ventral segmental areas which modulate pleasure and reward and drug seeking

what happens is there’s altered availability/influence of dopamine released by the ventral segmental area onto neurons in the nucleus accumbens

Question 18

what things can happen when there’s limbic system dysfunction?

Answer 18

1. disinhibited behavior: this means someone doesn’t consider the risk of behaviors and ignores social conventions/rules
2. increased anger and violence: this is commonly tied to amygdala damage
3. hyperarousal: amygdala damage, or damage to parts of the brain connected to the amygdala, can cause increased fear and anxiety
4. hypoarousal: this can cause low energy or lack of drive and motivation
5. appetite dysregulation: destructive behaviors tied to hyperorality or thalamus dysfunction can include overeating, binge eating or emotional eating
6. trouble forming memories: hippocampal damage can include short-term or long-term memory loss
7. learning is often greatly impacted by hippocampal damage, since learning depends on memory
8. someone with the condition anterograde amnesia loses the ability to form and retain new memories

Question 19

which 2 disorders are related to limbic system dysfunction?

Answer 19

1. Wernicke-Korsakoff syndrome

2. Kluver-Bucy Syndrome

Question 20

what is Wernicke-Korsakoff syndrome?

Answer 20

a neurological condition effecting the limbic system resulting from thiamine B1 deficiency – almost always related to chronic alcoholism

Wernicke = acute neurological disease with confusion, ataxia, eye abnormalities

Korsakoff = chronic form of dementia, memory loss –> once you start to have dementia symptoms it can’t be reversed

patient will present with pronounced anterograde amnesia, ataxia, impaired declarative memory, and confabulation – procedural/non-declarative motor action memory remains intact

causes problems learning new information, inability to remember recent events and long-term memory gaps. Memory difficulties may be strikingly severe while other thinking and social skills are relatively unaffected

Question 21

what is Kluver-Bucy Syndrome?

Answer 21

results from bilateral lesions of the amygdala and adjacent temporal lobe structures

results in placidity, decreased aggressive behavior, fearlessness and having little emotional reaction, visual agnosia, hyperorality, hypersexuality

Question 22

what are the 2 theories of emotion?

Answer 22

1. James Lange theory of emotion

2. Schachter-Singer Two-Factor Theory of Emotion

Question 23

what is the James Lange theory of emotion?

Answer 23

our emotions are felt based directly upon what our body is experiencing as physical sensations

ex. 1st Heart racing, perspiring then 2nd I see a bear; my muscles tense, my heart races. I then” feel afraid due to physiology -evaluated as anxious/stressed

so this is feeling first that then creates a label based on the physiological effect

classical conditioning explains some fear and anxiety disorders by means of James Lange and the Limbic System

Question 24

what is the Schachter-Singer Two-Factor Theory of Emotion?

Answer 24

emotion is based on two factors: physiological arousal and cognitive label that we give it

ex. 1st - Heart racing, perspiring and then 2nd at a favored concert and having energetic fun – labeled excitement, not fear or anxious and this is because cognitively you’re labeling it differently even though both fear/anxiety and excitement produce a racing heart and perspiration

so how we label the physiological sensation impacts what emotion we have

this cognitive theory can explain despair, anxiety and other disorders by means of Two factor model and Limbic system