Emotion

1. Emotion • It is a big concept, not easy to define. • Drever (1964) Emotion involves ‘bodily changes of a widespread character- in breathing, pulse, gland secretion, etc.- and on the mental side, a state of excitement or perturbation, marked by a strong feeling.’

2. How do we explain such Emotion? • In 1908, a case study of a mentally disturbed woman was reported. She repeatedly tried to choke herself with her left hand. Her right hand would try to pull the left hand away. Her left hand would also tear pillows & sheets. • When she died, a post mortem revealed that she had a damaged corpus collosum! • Charles Whitman killed his wife, mother, 15 people he did not know & wounded 24 before being killed by the police. Beforehand, he wrote of the agony he experienced in his emotions! • A post mortem revealed a small tumor, possibly near to or in the amygdala (the wounds caused by the police gun fire made it difficult to locate the tumour exactly)

3. Components of Emotion • Cognitive: Emotions are usually directed towards people or objects. • Physiological: Increased heart rate, increased blood pressure, etc. Arousal occurs in the Sympathetic division of the ANS or hormonal activity in the Endocrine system. • Experimental: This is the feeling that is experienced, which can only be assessed in the human species (methodological considerations!) • Expressive: This is facial expression & other aspects of non-verbal behaviour such as bodily posture. Emotions are inferred from these expressions. • Behavioural: Should I ‘Fight’ or ‘Flight’?

4. Emotion and the brain • Bard (1928) found that removal of part or all of the cerebral cortex produced ‘full blown rage’ in cats. The cortex normally acts as an inhibitor of sub-cortical structures which are responsible for the production of emotional behaviour. • This ‘Sham rage’, was the integrated expression of rage, without the characteristics of normal emotion. • Stimulation of various parts of the hypothalamus in non-human animals reveals that it is also involved in the full expression of emotional behaviour. However Sem-Jacobsen (1968) found that hypothalamic stimulation had little effect on emotional experiences in Humans. • Kluver & Bucy (1937) showed that damage to the Limbic system had effects on monkey’s emotional behaviour. They displayed increased sexuality, decreased fearfulness & increased aggression towards others. • Destruction of the Amygdala made wild & ferocious monkeys tame & placid. Some evidence suggests that the amygdala plays a similar role in humans. • Kluver, Bucy & others were instrumental in the development of Psychosurgery. • Mark & Ervin (1970) studied a young woman called Julia, who committed without provacation, twelve separate attacks on people. Tests suggested that her amygdala was damaged. A small lesion was performed in the amygdala to reduce her aggressive behaviour. Follow up studies reported a reduction in her aggressive behaviour.

5. Brain systems in Emotion The Papez Circuit (1937) • Papez studied cases of rabies & brain damaged individuals. • Papez proposed that a complex set of interconnected pathways & centres in the limbic system underlies emotional experience. • The circuit consists of a closed loop that runs from the hippocampus to the hypothalamus & from there to the anterior thalamus. The circuit continues via the Cingulate gyrus & the Entorhinal cortex back to the hippocampus.

6. The limbic system • Papez’s proposals have not stood the test of time. Maclean (1949) modified the circuit & suggested that the amygdala & the hippocampus play a central role in the mediation of aggression, but the cingulate gyrus does not! • The Papez-Maclean model has been influential, however, caution is given to the idea that there are ‘specific emotion centres’ in the brain. • If someone surprises you, an initial response is to jump. According to LeDoux (1996) the amygdala receives sensory information, therefore an emotional response can be elicited independently of the cortex. This is called a pre-cognitive emotional response. The amygdala is the ‘early warning system’. When the cortex appraises the situation, then a decision can be made!

7. The cerebral hemispheres & Emotion • As we already know, if the corpus collosum is divided, the channel of communication is disrupted & the hemispheres are no longer in tact. It has been suggested that the two hemispheres might differ in terms of their comprehension & communication of Emotion. • Damage to the motor area of the right hemisphere leads to paralysis of the left side of the body. They respond with indifference to this, e.g., they still make plans to walk! • Damage to the motor area of the left hemisphere leads to paralysis of the right side of the body. This causes a catastrophic reaction, marked by severe anxiety & depression (probably a result of the awareness of brain damage) • Does the right hemisphere recognise the emotion-provoking stimuli & organise the appropriate pattern of emotional responses? • Does the left then, not take account of the emotional significance of the damage, & so continue to make plans without taking it into consideration? Even though it may be aware of the damage, it doesn’t seem bothered by it! • People with intact brains show the left hemisphere is more active when people experience positive emotions, & the right hemisphere is more active when people experience negative emotions.