Chapter 9: Emotion

Urbach-Wiethe Disease


Urbach-Wiethe disease is an impairment in perceiving others' emotions. SM had bilateral damage to the amygdala. His intelligence scores were normal but he was not able to understand fear. 


Basic Emotions and the Dimensions


There are six basic human facial expressions: anger, fear, disgust, happiness, sadness and surprise. There are two basic dimensions for emotions. Valence, which distinguishes between pleasant and unpleasant emotions and arousal, which is how intense the emotional response is.  Richard Davidson has two other items: withdraw and approach. Approach is the idea that stimulus that is either happy or surprising leads us to approach the situation, but fear and disgust leads us withdraw from the situation. Typically, withdraw goes hand-in-hand with negative valence.


Limbic System


James Papez come up with the circuit theory of brain and emotion. It says that emotional responses involve a network of brain regions. Including the hypothalamus, anterior thalamus, cingulate gyrus and the hippocampus. However, there is not much evidence that shows the hippocampus plays a role in emotion.


Amygdala


Heinrich Kluver and Paul Bucy damaged the amygdala in monkeys and observed the deficit called psychic blindness. They found that they tended to approach items that would usually elicit a fear response. However, the lesions may have been sloppy; they probably damaged the surrounding areas of the amygdala as well as the amygdala itself.


Others have done studied fear conditioning in rats. Before training a light was shown and the rats showed no response; however, with the foot shock and loud noise they did show a response. During the training the paired the light and shock, which elicited a fear response. Eventually the light alone would produce the same response. When the light and sound were paired it also produced a fear response, this is called the potentiated CR. They learned response was impaired when the amygdala is damaged. 


SP had bilateral damage to the amygdala. SP was unable to recognize fear in faces. During the learning phase they were just shown a picture of a blue square. During the acquisition phase, they were given a shock to the rest and the end of the presentation of the blue square. They had a normal response when the shock was presented but there was no change when the blue square was shown. SP has declarative knowledge but no behavioral response. Patients with bilateral damage to the hippocampus and not the amygdala produce a normal behavioral response but they cannot explain why they responded that way.


Social Response (facial expressions and social grouping)


When presented a picture of a face with a fearful expression, the amygdala will increase in response. The deficit is only with the recognition of facial expressions because they are able to generate and communicate their own facial expressions.  The reason SM may not be able to recognize fear is because fear is mostly shown in the eyes. Other emotions are shown in other parts of the face. SM did not focus on the eyes, instead they looked at other parts of the face.


Behavioral research examines behavioral responses that demonstrate preference for one group over another. Bias is calculated by the difference in the response latency between the black + good/white +bad trials versus the black + bad/white + good trials. Elizabeth Phelps used an MRI to see activation in white subjects when viewing black and white faces. When these subjects saw a picture of an unfamiliar black face the amygdala was activated.