Week 8 L14 Flashcards
An Evolutionary Perspective: Charles Darwin (1887) of emotion
Cross-species similarities
The Principle of Antithesis:
Opposite messages are signaled by opposite movements and postures.
Gulls agression BEAKS towards each other, submission = away from each other. Or stare vs avert eyes for monkeys. EASILY DISTINGUISHIABLE. Or dog all up vs all down.
Anger, fear, suprise, happy, cross cultural. Special
Emotion
Collection of responses varying on dimesnions,
verbal report,
Non verbal. Response to sit. Facial expression,
Theories of Emotion: The Commonsense view
- Perceptionoftheemotion-eliciting event (e.g. see a bear).
- Subjectivefeelingsofemotion (e.g. fear).
- Behavioralandadaptive physiological responses (e.g. trembling, sweating and running away).
Perception, feeling, behaviour!
Theories of Emotion: The James-Lange Theory
- Perception of emotion-eliciting event (e.g. see a bear).
- Appropriate set of physiological responses are triggered (e.g. sweating, trembling, increased heart rate).
- The emotional event also triggers adaptive behaviours (e.g. clench fists, run away).
- The brain receives feedback from the peripheral nervous system which constitutes our feelings of emotion.
We feel our emotion, different from common sense, so behaviour leads to feeling, feeling comes after! Viscera tos low to respond to feelings of emotion?
Epafeb again.
Event, perception, action, feeling!, emotion, Behaviour.
Walter Cannon’s Problems With The James-Lange Theory of emotion
- The internal organs (or viscera) are relatively insensitive and do not respond quickly enough to account for our emotional feelings. No so substantial, though is still reasonably fast.
- Cutting the sensory nerves between the internal organs and the central nervous system does not abolish emotional behaviour in animals.
Difficult to test experimentally.
Support for James-Lange Theory of emotion
§ Hoffman (1966)
- Studied paraplegics who had spinal cord surgery at
different levels.
- Patients were asked about their emotional feelings.
- Those with highest transections (i.e. surgery high up the spinal cord) showed less intense emotional feelings.
- Other subjects showed angry behaviour (the emotional response) without feeling angry.
- Thus, the emotional experience lacked the intensity that was experienced before the surgery.
The Limbic System and Emotion: The Papez Circuit (1937)
FEELINGC
Cingulate cortex
Hippocampus (included amygdala at the time)
Anterior Thalamus
Hypothalamus
BEHAVIOUR
Sensory input diverged into different pathways or ‘streams:’ a stream of thought and a stream of feeling.
The pathway could be transmitted upstream (towards the cortex) or downstream (to the brain stem and spinal cord).
Pathway from hypothalamus to cingulate cortex involved in subjective emotional experience.
Connections back to the hypothalamus via hippocampus enabled expression of emotion.
The Kluver-Bucy Syndrome
(Posted around same time as paper work)
What did is show.
- In 1939, Heinrick Klüver and Paul Bucy showed that monkeys with temporal lobe lesions (included hippocampus and amygdala) showed:
- reduced fear
- hypersexuality
- hyperorality
- hyperaggression
- hypermetamorphosis: rect to every visual feature, recognition memory failed. - In 1950’s, the Kluver-Bucy syndrome could be induced with aspiration lesions of the amygdala (e.g. Weiskrantz, 1956). Non selective operation though.
- In 1970 – 1990’s, The amygdala was gradually dissociated from the hippocampus (e.g. Aggleton and Passingham, 1981; Murray et
al., 1992; Meunier et al., 1993) - 1990’s onwards, excitotoxic lesions of the amygdala led to significant deficits in fear expression and ‘mild’ if at all Kluver-Bucy symptoms.
The Amygdaloid Complex
The lateral nucleus receives information from the prefrontal cortex, thalamus and the hippocampus. It projects to the basal ganglia and the dorsomedial thalamus as well as the basal and accessory basal regions of the amygdala.
The medial nucleus consists of several subnuclei which receive sensory input. This information is then relayed to the basal forebrain dand hypothalamus. Involved in reproductive functions.
Activation of the central nucleus elicits a variety of emotional responses
See diagram I think .
Nucleus accumbans is sseme as
Ventral striatum, part of basal ganglia system!
Fear and the Amygdala: Role of the Central Nucleus
§ The central nucleus of the amygdala is particularly important for the expression of emotional responses to aversive stimuli.
§ Neural activity of the central nucleus increases in the presence of threatening stimuli.
§ Animals with lesions of the central nucleus do not show fear when confronted with aversive events. They are tame when handled and show low levels of stress hormone.
§ When the central nucleus is stimulated, animals are highly fearful, agitated and show stress induced illnesses (e.g. ulcers).
Chronic stress, amygdala central nulues mediates experience of stress.
The central nucleus of the amygdala sends information to various brain structures which control different emotional responses
See diagram!
Learning to Fear: Fear Conditioning (LeDoux, 2000)
On
10 s Off
0.5 s
Tone (CS) Shock (US)
Paired Unpaired
% Freezing
% Freezing
% Freezing, classic response.
Habituation, conditionivng, testing.
Sim to Pavlov dogs.
Lesion to centrl amygdala, fearless, losing me dory of emotion. No freezing.
Pairing of stimuli super imp. Paired, and unpaired group, see differences in graphs. Predictable. Testing, non paired back to baseline w/0 freezing response.
Some useful terms….?
§ When a neutral stimulus (e.g. tone) is paired with an aversive stimulus (e.g. shock), the tone will to elicit the emotional response (i.e. freezing)
§ The neutral stimulus becomes the “conditioned stimulus” (CS) and the elicited emotional response becomes the conditioned response (CR).
§ If the CS is presented alone repeatedly by itself, the CR, that is the emotional response of freezing, will eventually disappear. This is known as extinction.
§ Extinction is NOT the same as forgetting. In extinction, the animal learns that the CS is longer followed by an aversive stimulus. Therefore, the CR expression is inhibited.
§ The memory of the association between the CS and the aversive stimulus is not erased; it can be reactivated. Brief retinitis tion needed, as it is labile and just inhibited over time. Unless re initiated.
A Behavioural Test of Emotional Reactions to Fear Provoking Stimuli in Monkeys
Snake, ucr of fear.
Spider Neutral
Monkeys are allowed to reach over a rubber snake, a fake spider and a neutral object to retrieve a food reward
Dependent variables:
- Food-retrieval latencies
- Video record monkey’s behavior
Unconditional reward.
Saw videos, throws grape lol.
Research with Humans, damaged amygdala, startle response but no conditional emotional response. Like monkeys.
§ People with amygdala damage fail to acquire conditioned emotional responses (Angrilli et al., 1996).
§ Damage to the amygdala effects emotion on memory (Cahill et al., 1995).
§ The activity of the amygdala increases when subjects recall emotionally arousing films (Cahill et al.,1996).
§ Seeing words that denote
threatening situations increases amygdala activity (Isenberg et al.,
Physiological response take longer to subside, than startle response, patients amygdala damage fail to show prolonged started response, muscles reurn to normal
