Lecture 24, 25: Amygdala, Orbitofrontal and Cingulate Cortex Flashcards
What is the origin of the word amygdala ?
Almond-like (from the Greek)
Where is the amygdala?
- Within the uncus
- Anterior to the hippocampus
True or False
The amygdala is not a single structure.
True
It consists of nuclei
What is a nuclei?
- group of cells
- Each nucleus has unique inputs and outputs and neurotransmitter systems
True or False
Each nuclei has a differen function
True
This is why they have different input, outputs and neurotransmitter systems
True or False
We can see the nuclei in the amygdala with stains
True!
What is the structure that provides an important route by which external stimuli can have an impact on emotions?
Amygdala
What is the path that an external stimuli has to take in order to have an impact on our emotions?
Sensory areas → Amygdata → Subcortical structures → Physiological responses and behaviour
What are the 3 different types of nuclei in the amygdala?
- Lateral nucleus
- Central nucleus
- Basal nucleus
What is the Lateral nucleus?
- Function:
- Input region or Gatekeeper of the amygdala
- Input:
- from sensory systems
- Output:
- central nucleus
What is the central nucleus?
- Function:
- output region for the expression of innate emotional and associated physiological responses
- Input:
- lateral nucleus
- Output:
- connections to brainstem areas that control specific behaviours and physiological responses
What is a basal nucleus?
- Function:
-
output to the striatal areas involved in the control of instrumental behaviours
- Actions reach a goal
-
output to the striatal areas involved in the control of instrumental behaviours
- Input:
- Output:
True or False
The nuclei in the amygdala are connected.
True
From where does the amygdala receive input from?
- Entorhinal cortex
- Sensory cortex
- Ventromedial frontal cortex
- Polysensory and limbic association areas
What does it mean when we say that the amygdala receives information from the entorhinal cortex?
It receives input from the sensory cortical areas
What does it mean when we say that the amygdala receives input from the polysensory and limbic association areas?
- Cingulate gyrus
- Temporal pole
- Insula
- Perihinal cortex
- Frontal cortex
Where is the cingulate gyrus?
It is in the medial view of the brain, on top of the CC
Where is the temporal pole?
Where is the insula?
It is inside the Silvian Fissure hidden under the frontal, parietal and temporal opercula
Where is the perirhinal cortex?
It is within the lateral bank of the rhinal sulcus
To where does the amygdala outputs information?
- Orbitofrontal cortex
- Neocortex
- Striatum
- Hypothalamus
What is the function of the orbitofrontal cortex?
Hyperactivity and impulse control
What is the neocortex?
- Almost every visual region in the temporal and occipital lobes (including V1)
What is the function of the neocortex?
Modulation of sensory processing by affective state.
Emotional information becomes linked to sensory information.
What is the striatum?
- The striatum is composed by:
- putamen
- caudate nucleuse
- globus pallidus
In purple in the image
Where is the hypothalamus?
What is the function of the hypothalamus?
- Receives sensory input from the amygdala
- Influence on the autonomic nervous system
- breathing, heart rate, arousal
- Influence on the physiological responses and our behaviour
What is the difference between the hippocampus, hypothalamus and thalamus?
-
Hippocampus:
- Memory
-
Hypothalamus:
- the autonomic nervous system, physiological responses and behaviour
- heart rate, breathing, arousal
- the autonomic nervous system, physiological responses and behaviour
-
Thalamus:
- grand central station for information
What is the role of the amygdala?
- Important affective processing
- recognition of unpleasant emotions
- Associate external stimuli and events with aversive sensory inputs
- Helps establish emotional significance of external stimuli
- Updating stimulus
- update associations
What are the symptoms of bilateral amygdala damage?
- Change in emotional behaviour/hypoemotionality
- decrease in aggression, increase in indifference
- Lack of fear to the stimuli and situations that commonly evoke fear
- Kluver-Bucy syndrome
- No effect on most memory tests (with selective amygdala damage)
- Impact on social learning rather than a global loss in affective behaviour
What are the two aspects of reward?
- Feedback
- Intrinsic value
What is feedback?
- Feedback indicates correct responses on task
- ex)
- visual discrimination task
- delayed non-match to sample task (DNMS)
- ex)
What is Delayed non-match to sample task?
- An initial object is shown
- After some delay, two objects are shown
- Goal is to select the novel object
- If selected correctly gets reward
What is intrinsic value?
It is the preference, like and dislikes.
For example, smell and taste of a cup of coffee
True or False
The amygdala plays a role in the intrinsic value, not in feedback
True
True or False
Patients with bilateral lesions in the amygdala can learn visual discrimination and delayed non-match-to sample task using reward as feedback.
True
A+ animals can perform DNMS
Why do we say that the amygdala only plays a role in the intrinsic value and not the feedback?
The amygdala’s function is the formation of stimulus-value associations between discrete stimuli and their intrinsic reward value
What were the symptoms of damage to the amygdala in monkeys?
- Disturbed association between new items and their intrinsic value
- Put non-food into mouths
- Abnormal willingness to eat meat or other uncommon food
- Greater impact on learning new food preferences than on already established preferences
- can’t form new associations
- Can distinguish edible from non-edible items but they keep putting non-edible items in their mouth
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