Lecture 5- Emotions and Stress Flashcards
What did Duchenne de Boulogne discover about facial expressions?
Using muscle stimulation, he identified that the orbicularis oculi and zygomaticus major muscles are key in expressing happiness.
How are all emotions expressed in the body?
Through visceral motor changes (like heart rate, blood flow, and piloerection) and somatic motor responses (such as movement of facial muscles).
What is a Duchenne smile, and how is it controlled?
A Duchenne smile is an involuntary, emotion-driven contraction of muscles around the eyes and cheeks, controlled by the anterior cingulate gyrus and extrapyramidal pathways.
What is a pyramidal smile, and how is it controlled?
A pyramidal smile is a voluntary smile driven by the motor cortex, using brainstem and spinal cord circuits via the pyramidal tracts.
What is emotional facial paresis, and what causes it?
Emotional facial paresis is the inability to smile in response to emotions, caused by a tumor in the left thalamus interrupting extrapyramidal pathways.
What is voluntary facial paresis, and what causes it?
Voluntary facial paresis is the inability to smile voluntarily, caused by a lesion in descending fibers from the right motor cortex.
What did Phillip Bard’s 1928 experiments reveal about the hypothalamus and emotional behavior in cats?
Phillip Bard’s experiments showed that the hypothalamus controls emotional reactions like “sham rage” in cats, which displayed anger behaviors such as raised fur and extended claws, even without their cerebral hemispheres.
What was Hess’s contribution to understanding the hypothalamus’s role in emotion?
Hess demonstrated that direct stimulation of the hypothalamus could elicit defensive postures and a rage response
What is the “Papez circuit” and what are its components?
The “Papez circuit” is a pathway in the limbic system critical for emotional control
- involves the cingulate cortex, hippocampus, mammillary bodies, and anterior thalamus.
What is the role of the cingulate cortex and hypothalamus in the original conception of the limbic system?
The cingulate cortex is critical for experiencing emotion, while the hypothalamus integrates sensory information and governs emotional expression.
What behavioral changes result from the removal of large parts of the temporal lobes in monkeys, as studied by Kluver and Bucy?
Removal leads to visual agnosia, bizarre oral behaviors, hyperactivity, hypersexuality, and drastic changes in emotional behavior
How does the modern conception of the limbic system relate to Kluver-Bucy Syndrome?
Kluver-Bucy Syndrome is thought to result from disruption of the Papez circuit in the limbic system.
How can Kluver Bucy Syndrome be triggered in humans?
It can be triggered by bilateral temporal lobectomy or by removal to the amygdala alone.
What did John Downer’s 1950s experiment reveal about the amygdala’s role in emotional behavior?
Downer’s experiment showed that the amygdala is crucial for emotional responses like fear and aggression, as monkeys displayed different behaviors depending on whether the amygdala was intact or removed.
How did monkeys behave when viewing the world with and without an intact amygdala?
When using the eye connected to the intact amygdala, monkeys showed normal fear and aggression. Without it, they displayed reduced fear and aggression, similar to Kluver-Bucy Syndrome.
How does the human amygdala respond to viewing fearful faces compared to happy or neutral faces?
Viewing fearful faces increases activity in the amygdala, while there is no response to happy or neutral faces.
What effects does electrically stimulating the amygdala have on behavior?
Stimulating the amygdala increases vigilance and attention, and stimulating the basal-lateral amygdala specifically can elicit fear and aggression.
What were the effects of amygdala damage on patient SM’s ability to recognize and respond to fear?
Patient SM could not recognize fear in others and had a reduced ability to experience fear herself, despite understanding potential dangers.
How did amygdala damage affect Patient SM’s ability to detect fear, and what changed when she was instructed to focus on the eyes?
Patient SM normally looked at mouths, missing fear cues in the eyes. When told to focus on the eyes, she could detect fear, indicating disrupted amygdala-visual cortex interaction.
How does the amygdala respond to evaluating the trustworthiness of faces?
The amygdala becomes more active when judging face trustworthiness, with the highest activation for faces seen as untrustworthy, whether consciously or subconsciously
What is the function of the medial group in the amygdala?
The medial group connects to the olfactory bulb and cortex, linking the amygdala with the sense of smell.
Which amygdala group is the largest in humans, and what are its main connections?
The basal-lateral group is the largest in humans and connects with the medial prefrontal and orbital cortex, areas involved in decision-making and emotion.
What is the role of the central group in the amygdala?
The central group connects with the hypothalamus, brainstem, and visceral sensory structures, helping the amygdala regulate body responses during emotional experiences.
How do the different groups within the amygdala contribute to emotional behavior?
These connections link sensory processing areas with emotional effector systems (e.g hypothalamus and brainstem) , allowing the amygdala to drive emotional responses.
What direct inputs does the amygdala receive, aside from cortical inputs?
The amygdala receives direct input from the thalamic nuclei, olfactory bulb, and brainstem, which relay basic sensory information.
How do amygdala neurons respond to complex stimuli, and which group is involved?
Amygdala neurons respond to complex stimuli, like faces, with the basal-lateral group specifically responding to the sight of faces.
What circuit does the basal-lateral amygdala participate in, and which areas does it connect to?
It forms a triangular circuit connecting the mediodorsal thalamus to the orbital and medial prefrontal cortex.
What did LeDoux’s experiments reveal about learned fear and its mechanism?
His experiments showed that animals can learn to fear a neutral stimulus by associating it with something aversive. This “cued” learned fear likely involves a mechanism similar to long-term potentiation (LTP).
How does the amygdala receive sensory information to create a conditioned fear responses?
It receives auditory input from the cortex and medial geniculate nucleus (MGN), as well as pain signals through somatic sensory pathways.
- Integrates them to trigger both physical (somatic) and internal (visceral) fear responses.
Which areas of the orbital frontal cortex are associated with pleasure responses?
The medial and mid-anterior OFC show increased activity in response to rewards like money or tastes.
What role does the lateral OFC play in emotional processing?
The lateral OFC monitors responses to punishments.
What are the key steps in the stress response triggered by fear?
- Fear triggers hypothalamus
- Parvocellular neurons of
hypothalamus secrete CRH (corticotropin-releasing hormone) - CRH prompts pituitary gland to release ACTH (adrenocorticotropin hormone)
- ACTH increases cortisol levels
- Cortisol promotes “fight-or-flight” response
How does altering CRH receptors in mice affect anxiety-like behaviors?
Overexpressing CRH receptors in mice increases anxiety-like behaviors (e.g., excessive grooming), while deleting CRH receptors has an anxiolytic, or stress-relieving, effect.
