Brain mechanisms of emotion Flashcards
what is affective neuroscience?
The investigation of the neural basis of emotion and mood.
What is the James-Lange theory of emotion?
-we experience emotion in response to physiological changes in our body
-the emotion you experience consists of your feelings that result from the changes in your body
-e.g., instead of jumping out of bed because your scared of spider, you feel scared because you become aware of your heart racing and tensed muscles
-the bodily changes cause emotion rather than the other way around
What is the Cannon-Bard theory of emotion?
-Emotional experience can occur independently of emotional expression
-eliminating senses does not eliminate emotions as James-Lange theory suggests
-stated same physiological changes occur in other states, e.g., anger and fear, and even nonemotionally conditions of illness, such as fever
-This theory focused on the idea that the thalamus plays a special role in emotional sensations –> sensory input received by the cerebral cortex, which in turn activates certain changes in body
- According to Cannon, this stimulus-response neural loop is devoid of emotion. Emotions are produced when signals reach the thalamus either directly from sensory receptors or by descending cortical input. in other words, the character of the emotion is determined by the pattern of activation of the thalamus irrespective of the physiological response to the sensory input.
What is the concept of unconscious emotion?
-suggest that sensory input can have emotional effects on brain without our being aware of the stimuli
-experiment conducted by Arne Ohman, ray Dolan et al. briefly showing angry face followed by expressionless face, subjects reported only seeing expressionless face –> angry face is “masked” by expressionless face –> subjects were conditioned with mild shock to finger when angry face sowed –> when shock was absent and face was shown they still exhibited autonomic responses (increased skin conductance due to sweat)
-amygdala responded in PET hen angry faces were conditioned
what does the limbic lobe consist of?
-cortex around the corpus callosum (mainly cingulate gyrus), cortex on medial surface of the temporal lobe, and the hippocampus
What is the Papez circuit responsible for?
-links cortex with hypothalamus
-involved in experience of emotion
-cingulate cortex projects to the hippocampus, the hippocampus projects to hypothalamus by way of the bundle of axons called fornix. Hypothalamic effects reach the cortex via a relay in the anterior thalamic nuclei
-communication is bidirectional –> therefore compatible with both James-Lange and Cannon-Bard theories of emotion
describe rabies
-indication of rabies infection is presence of abnormal cytoplasmic bodies in neurons, especially in hippocampus
-characterised by hyperemotional responses such as exaggerated fear and aggressiveness –> because of this papez reasoned that the hippocampus must be involved in normal emotional experience
What is the limbic system?
-the group of structures in the Papez circuit
describe basic theories of emotion
-certain emotions are thought to be unique, indivisible experiences that are innate and universal across cultures
what are basic emotions?
-anger, disgust, fear, happiness, sadness and surprise
what parts of the brain are more active when sadness or fear are demonstrated?
-fear –> amygdala
-sadness –> medial prefrontal cortex
describe dimensional theories of emotion
-theories are based on the idea that emotions, even basic emotions can broken down into smaller fundamental elements combined in different ways and differing amounts, –> e.g., all elements of periodic table made up of protons, neutrons and electrons
describe the proposed affective dimensions of valence and arousal
-valence –> pleasant-unpleasant
-arousal –> weak emotion-strong emotion
-imagine a 2d graph with axes labelled in these ways, each emotional experience would be located in a different part of the graph.
descibe psychological constructionist theories of emotion
-variation on dimensional theories
-similar to dimensional theories in the sense that emotions are said to consist of smaller building blocks
-key difference is that in the constructionist models, the dimensions do not carry affective weight
-instead dimensions such as pleasantness, an emotional state is constructed from physiological processes that, on their own, do not concern only emotion
-examples of non-emotional psychological components that construct emotion are things like language, attention, internal sensations from the body, and external sensations from the environment
-the emotional is an emergent consequence of the combination of these components – just as cakes results from combination of ingredients
what is Kluver-Bucy syndrome?
-the removal of the temporal lobes (done on monkey)
-good visual perception but poor visual recognition
-increased interest in sex
-decreases in fear and aggression
-decrease in vocalisation and facial expression usually associated with fear
-these features also seen in humans with temporal lobe lesions –> more specifically amygdala lesions
where is the amygdala located?
-in the pole of the temporal lobe, just below the cortex on the medial side of the temporal lobe
