Emotion Flashcards
Significance of Emotions
Basis of studying behavioural manifestations (animal models, brain lesions and human brain imaging techniques). Emotional experience leads to emotional expression.
Affective neuroscience
neural basis of emotion and mood
James-Lange Theory of emotion
Emotion is result of a response to physical changes in the body
Cannon-Bard Theory of emotion
Emotions independent of emotional expression
Contrasting+complimenting views of (J-L) vs (C-B) theories
Stimulus percieved leads either to emotional experience (fear, for example) shapes emotional expression (C-B). Opposing this is a visceral response from perceived stimulus leading to an emotional experience.
Unconscious emotions
Stimulus can have an emotional impact without conscious awareness. For example: aversive conditioning to masked stimulus results in increased skin conductance–resulting in increased activity in the amygdala
Broca’s limbic lobe
Cortex forming a ring around corpus callosum: Cingulate gyrus, medial surface temporal lobe, hippocampus.
Papez Circuit (limbic system) loop
Limbic structures, including cortex, are involved in emotion.
Emotional system on the medial wall of the brain linking cortex with hypothalamus.
(1)NeoCortex(2)Cingulate cortex (emotional experience)—> (3) Hippocampus—(fomix)–> (4) Hypothalamus (emotional expression)—–>(5) Anterior nuclei of thalamus—–> (2)C-C
Papez circuit basis
Cortex: emotional experience
Hippocampus: Behavioural expression of emotion
Rabies infection implies that hippocampus is involved in emotion (hyperemotional response)
Anterior Thalamus: lesions lead to spontaneous laughing+crying
Limbic system (who popularized and what the evolution means)
Maclean popularized the term.
Evolution of limbic system allows animals to experience emotions beyond stereotyped brain stem behaviours (reptilian brain behaviours)
Single emotion system concept (difficulties)
- Diverse emotions
- Many structures involved in emotion
-No one-to-one relationship between structure and function
Limbic system: Utility of single, discrete emotion system questionable
Klüver-Bucy Syndrome
Temporal lobectomy in rhesus monkeys:
- Decreased fear and aggression
- Decreased vocalizations and facial expressions
Temporal lobectomy in humans
Exhibit symptoms of Klüver-Bucy syndrome:
-Flattened emotions
-Probably related to destruction of the amygdala
Amygdala and Fear
Bilateral amygdalectomy reduces fear and aggression in all animals tested:
-Anger, sadness, and disgust may also be affected
S.M. case study
Inability to recognize fear in facial expressions
Electrical stimulation of amygdala -> Increased vigilance or attention
Fearful faces produce greater amygdala activity than happy/neutral faces
Is involved in forming memories of emotional events
Amygdala (confirmed by fMRI and PET imaging)
Amygdala and Aggression (2 types)
- Predatory aggression-Attacks
2. Affective aggression-for show
(Potential) Goal of amygdalectomy and psychosurgeries
reduced human aggression:
- Reduced aggressive asocial behavior
- Increased ability to concentrate
- Decreased hyperactivity
Hypothalamus and it’s involvement in Aggression
Removal of cerebral hemispheres but not hypothalamus -> sham rage
- Behaviour reversed with small lesions in hypothalamus
- Hypothalamus may normally be inhibited by telencephalon.
Hypothalamus and aggression (Flynn, 1960)
- Elicited affective aggression by stimulation medial hypothalamus
- Predatory aggression elicited by stimulating lateral hypothalamus
Midbrain and Aggression
Two hypothalamic pathways to brain stem involving autonomic function:
(1)Predatory aggression:
Medial forebrain
bundle -> ventral tegmental area
(2)Affective aggression Dorsal longitudinal
fasciculus -> periaqueductal grey
Serotonin and aggression
Serotonergic raphe neurons project to the hypothalamus and limbic structures via the medial forebrain bundle:
↓Serotonin turn-over
↑aggression in rodents
Drug PCPA blocks serotonin synthesis ↑aggression
Serotonin Receptor Knockout Mice
14 serotonin receptor subtypes Knockout Mice (recombinant DNA techniques)
5-HT1A and 5-HT1B
5-HT1A and 5-HT1B; autoreceptors—global regulatory role
5-HT1B High concentrations in raphe nuclei, amygdala, PAG, basal ganglia
Agonists: Decrease anxiety, aggressiveness
Neural pathway overview of emotions
Experience, expression of emotion involves widespread activity in the nervous system from cortex to ANS as well as: limbic structures, hypothalamus, amygdala
