Emotion Flashcards
What are the 6 main emotions?
Anger
Fear
Surprise
Sadness
Joy
Disgust
What are emotions?
A composite of subjective feelings, physiological responses, and behaviours that allow humans and other animals to react adaptively to internal and external stimuli
Explain the study by Duchenne (1862)
Gave pps electrical stimulation of the facial muscles
Bilateral electrical stimulation of the zygomaticus major muscle mimicked a genuine expression of happiness although shows insufficient contraction of the obicularis oculi compared with spontaneous laughter
What did Duchenne (1862) find in their study?
Faradization = electrocuting various muscles in the face
Found there were 2 types of smile
Voluntary smile = pyramidal smile, activates the zygomatic major muscle
Involuntary smile = Obicularis oculi (cannot be voluntary activated) (extra pyramidal)
How does voluntary facial paresis provide support for Duchenne?
Patients with unilateral facial paralysis due to damage of descending pathways from the motor cortex have considerable difficulty moving their lower facial muscles on one side either voluntarily or in response to commands - voluntary facial paresis
Many of them produce symmetrical involuntary facial movements when they laugh, frown or cry in response to stimuli
Evidence that there are separate pathways from the forebrain other than the classic motor cortex which activate facial movements
How do patients with emotional facial paresis provide support for Duchenne?
Loss of ability to express emotions by using the muscles of the face without loss of volitional control
Such individuals are able to produce symmetrical pyramidal smiles but fail to display spontaneous emotional expressions involving the facial musculature contralateral to the lesion
Describe the 2 separate systems for the pyramidal smile and the Duchenne smile
Volitional movement = descending pyramidal and extrapyramidal projections from motor cortex and brainstem
Connects to –> motor neuron pools in facial nucleus –> Activation of facial muscles (Pyramidal smile)
Lesion between these systems causes voluntary facial paresis
Neural systems for emotional expression = descending extrapyramidal projections from medial forebrain and hypothalamus
Connects to –> Motor neuron pools in facial nucleus –> Activation of facial muscles (Duchenne smile)
Lesion between these systems causes emotional facial paresis
What did Phillip Bard study?
Bard removed both cerebral cortex in a series of cats
When the anaesthesia wore off the animals behaved as if they were enraged
Cats also exhibited somatic motor components of anger such as arching their back - this behaviour was called sham rage
Found that a transection through the midbrain, disconnecting the hypothalamus and brainstem abolishes sham rage
Suggested that the hypothalamus was a key brain region in expression of emotion
What structures are in the Papez circuit?
Hippocampus
Amygdala
Thalamus
Hypothalamus
Parahippocampal regions
What is Kluver-Bucy syndrome?
Results from bilateral lesions of the medial temporal lobe including the amygdala
Symptoms
1. Visual agnosia
2. Increased oral tendency
3. Decreased emotional reaction
4. Hyper-sexuality
5. Hyper-metamorphosis
What are the subdivisions of the amygdala?
Medial group - connected with olfactory bulb and olfactory cortex
Basal lateral group - cortex, orbital and medial pre-frontal cortex, anterior temporal lobe
Central/anterior group with hypothalamus and brainstem
What are the inputs into the amygdala?
Auditory pathways –> Thalamus - Medial geniculate nucleus –> Auditory cortex or amygdala
Auditory cortex –> Amygdala
Somatic sensory pathways –> Amygdala
What is the process of fear conditioning in the amygdala - What pairs the stimuli and outputs?
Long term potentiation
Excitation causes frontal cortex connections
What are the outputs of the amygdala?
Central nucleus causes an output response e.g., freezing, blood pressure, stress hormones or startle reflex
What important structure is needed to unlearn the fear associations of the amygdala?
The medial prefrontal cortex
What conditions have a smaller amygdala?
Autism
Psychopathy
Brain injury such as stroke can affect the amygdala
What are the theories of emotion?
Common sense
James-Lange
Cannon-Bard
Schachter
What is the common sense theory of emotion?
Stimulus causes a conscious feeling i.e., fear which causes autonomic arousal
What is the James-Lange theory of emotion?
Stimulus causes autonomic arousal which in turn causes a conscious feeling of fear
What is the Cannon-Bard theory of emotion?
Stimulus causes subcortical brain activity which causes autonomic arousal and conscious feeling of fear simultaneously
States that the lower part of the brain, also called the thalamus, controls your experience of emotion. At the same time, the higher part of the brain, also called the cortex, controls the expression of emotion. It is believed that these two parts of the brain react simultaneously
What is the Schachter theory of emotion?
Stimulus –> autonomic arousal + appraisal –> conscious feeling
Physiological arousal determines the strength of the emotion, while cognitive appraisal identifies the emotion label
Describe the 2 separate systems for the pyramidal smile and the Duchenne smile
Volitional movement = descending pyramidal and extrapyramidal projections from motor cortex and brainstem
Connects to –> motor neuron pools in facial nucleus –> Activation of facial muscles (Pyramidal smile)
Lesion between these systems causes voluntary facial paresis
Neural systems for emotional expression = descending extrapyramidal projections from medial forebrain and hypothalamus
Connects to –> Motor neuron pools in facial nucleus –> Activation of facial muscles (Duchenne smile)
Lesion between these systems causes emotional facial paresis
What did LeDoux do in his study?
Trained rats to associate a tone with a mildly aversive foot shock delivered shortly after the onset of a sound
They measured blood pressure and the length of time the animals crouched without moving (freezing)
After training, the onset of the tone caused a marked increase in blood pressure and prolonged period of freezing
What did the results of LeDoux tell us about brain areas in emotion?
The medial geniculate complex (dorsal thalamus) is necessary for the development of the conditioned fear response
The responses were still elicited if the connections between the MGC and auditory cortex were severed, leaving only a direct projection between the MGC and the amygdala
