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 monkeys 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

• Papezs 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 doesnt 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.