NEURO: Emotion

Question 1

What is emotion?

Emotional expression?

Emotional experience?

Answer 1

a strong feeling deriving from one’s circumstances or mood

observable sign of an emotional state

feeling a person experiences

Question 2

Studying emotion in humans and animals

Answer 2

In humans, both emotional expression and experience can be studies

In animals, only emotional expression can be studied (not experience because you can’t ask an animal how it feels)

Question 3

Studying anxiety in animals

Answer 3

The elevated-plus maze test measures the conflict between the natural tendency of mice to explore a novel environment versus the tendency to avoid exposed areas.

The animals were positioned in the centre of the apparatus and left to explore for 5 mins. Anxiety-like behaviour was determined by calculating the amount of time spent and the number of entries each mouse made in the open and closed arms. The longer the mouse spends in open arms, the less anxious it is

Morphine withdrawn animals spent significantly less time and entries in the open arms compared to saline withdrawn animals.

prolonged withdrawal from morphine induces anxiety-like behaviour, which is consistent in humans.

Question 4

Studying depression in animals

Answer 4

Forced Swim Test:

• mouse put in beaker full of water to observe swimming behaviour in 6 minutes
• mouse then gets in an immobilised position just with head just above the water
• more immobility behaviour there is in the 6 minutes, more depressed the mouse

Question 5

How does morphine abstinence affect social interaction?

Answer 5

It was concluded that morphine withdrawal induced social interaction deficits in mice which is in agreement with the situation of opioid abstinent humans. Anxiety-like and depressive-like behaviour.

This was concluded based on tests on how long mice spent with unfamiliar mice.

Question 6

What are the two theories of emotion?

Answer 6

JAMES-LANGE:
This claims that we experience emotions in response to physiological changes in our body. No differentiation between expression and experience of emotion

CANNON-BARD:
This claims that we can experience emotions independently of emotional expression (no correlation with physiological state) .
The emotions are produced when signals reach the thalamus, either directly from sensory receptors or by descending cortical input.

Question 7

Explain the difference between the James-Lange and the Cannon-Bard theory of emotion.

Answer 7

The James-Lange theory: emotion experienced in response to physiological changes in body
The Cannon-Bard theory: emotions occur independent of emotional expression—no correlation with physiological state

So, with the James-Lange theory, you express, and thus you feel.
With the Cannon-Bard theory, you feel, and thus you express.

Question 8

What is the brain system responsible for emotions?

Answer 8

We have Broca’s limbic lobe. Limbus (latin) means border. It is a group of primitive cortical gyri that form a ring around the brain stem.

Broca’s limbic lobe includes:

• the parahippocampal gyrus
• the cingulate gyrus
• the subcallosal gyrus

Question 9

What is the papez circuit?

Answer 9

It’s a group of limbic structures, including cortex, involved in emotion.
It’s an emotional system on the medial wall of the brain linking the cortex with the hypothalamus.

The cortex is critical for emotional experience.
The hippocampus governs behavioural expression of emotion (the rabies infection implicates hippocampus in emotion: hyper-emotional responses).
Anterior thalamus lesions lead to spontaneous laughing or crying.

Evolution of limbic system allows animals to experience and express emotions beyond stereotyped brain stem behaviours.

Question 10

What constitutes the limbic system (as we define it)?

Answer 10

• cingulate gyrus
• parahippocampal structures
• septal nuclei
• amygdala
• enthorinal cortex
• hippocampal complex:
  
  • dentate gyrus
  • CA1-CA4 subfields
  • subiculum

Question 11

What are some general functions of the limbic system?

Answer 11

Anatomically, the limbic system appears to have a role in attaching a behavioural significance and response to a stimulus, especially with respect to its emotional content

Damage to the limbic system leads to profound effects on the emotional responsiveness of the animal.

Question 12

What are the functions of the cingulate gyrus?

Answer 12

• has a role in complex motor control
• pain perception
• social interactions-mood

Question 13

What are the functions of the hippocampus proper and parahippocampal areas?

Answer 13

• primary function in memory

Question 14

What are the functions of the amygdala?

Answer 14

• involved in learning and storage of emotional aspects of experience

Question 15

Why are there difficulties with the single emotion system?

Answer 15

There are difficulties due to the diversity of emotions and brain activity.

There are many structures involved in emotion, so there is no one-to-one relationship between structure and function.

Question 16

Describe the amygdala’s structure and connections.

Answer 16

It receives input from the neocortex:
- all lobes, including hippocampal, and cingulate gyri

It’s also connected to the basolateral nuclei, and receives information from all sensory systems.
It’s also connected to the corticomedial nuclei and the central nuclei.

Output to hypothalamus (region involved in expression of emotion)
Stria terminalis
Ventral amygdalofugal pathway

Question 17

What happens if we remove the temporal lobe?

Answer 17

Temporal lobe removal includes removing the temporal cortex, amygdala, and the hippocampus.

It resulted in:

• psychic blindness
• oral tendencies
• emotional changes (reduced fear)
• altered sexual behaviour

Question 18

What happens after an amygdalectomy?

Answer 18

• reduced fear
• reduced aggression
• reduced ability to recognise fearful expressions (can recognise happiness)
• flattened emotions

Question 19

What happens after an electrical stimulation to the amygdala?

Answer 19

• increased vigilance
• anxiety
• fear
• aggression

Question 20

How is the amygdala involved in the integration of current stimuli and past experiences?

Answer 20

The amygdala has involvement in giving emotional content to memories (fear conditioning).
It’s involved in PTSD.

The amygdala is involved in forming memories of emotional and painful events.
This is confirmed by fMRI images and PET imaging.

Question 21

What is aggression?

Answer 21

It’s multi-faceted behaviour (kill for freedom, murderer, power, dominance).
It’s governed by endocrine mechanisms (testosterone, castration).

Question 22

What are the two types of aggression?

Answer 22

BRAIN MECHANISMS:
Predatory aggression:
- when attacks are made against a member of a different species, to obtain food
- there is no sympathetic activity

Affective aggression:
- this is for show, threatening posture
- involves the social hierarchy
- there are high levels of sympathetic activity
(the amygdala plays an important role in aggression related to social hierarchy)

Question 23

Describe the neural components of anger and aggression beyond the amygdala.

Answer 23

Hypothalamus:
With the removal of cerebral hemispheres (cats) but not hypothalamus, we get a sham rage. If you remove both cerebral hemispheres and the anterior hypothalamus, you also get a sham rage
If you also remove the posterior hypothalamus, there is no sham rage.

In addition to these lesion cases, electrical stimulation of the hypothalamus leads to effective and predatory aggression.

Question 24

What are the two hypothalamic pathways to the brains stem involving autonomic function?

Answer 24

The two pathways are:
- the medial forebrain bundle to the ventral tegmental area; predatory aggression

• the dorsal longitudinal fasciculus to the periaqueductal gray matter; affective aggression

Question 25

Describe the relationship between serotonin and aggression (in primates)?

Answer 25

The serotonin deficiency hypothesis is that aggression is inversely related to serotonergic activity.

A 5HT antagonist will increase aggression, while agonists of 5HT1A or 5HT1B decrease anxiety and aggressiveness.

Also, in humans, there have been reports of a negative correlation between serotonin activity and aggression.