Dorsal Anterior Cingulate Cortex • Connected to areas of the brain involved in recognising an offense, registering a feeling and acting on it. • Links to reasoning centres in the frontal lobe and the memory centres in the limbic system.
Process• PET SCAN – Brain imaging technique.• Subjects are injected with a mildly radioactive chemical.• Images are averaged from multiple readings.• Can be difficult to react to anything other than the machine itself!• Solution – show scenes from films to evoke various emotions.
Findings• Dr. George conducted his studies with the same sex to avoid possible differences between sexes.• Findings:• Sad woman increased activity in the structures of the limbic system near the face,• More activity in the left prefrontal cortex than in the right.• Activation of the amygdala• Brain areas involved in ordinary sadness almost completely shut down when a person is clinically depressed.• Sadness and depression seem to involve the same brain region, the left prefrontal cortex, in different ways.• It gets more active during ordinary sadness, but shuts down in people with clinical depression.• Suggests the left prefrontal cortex may burn itself out when sadness persists for several months.
In sum of sadness• Limbic system closer to the face• Amygdala• Left prefrontal cortex (sadness)• Less activity in prefrontal cortex (depression))
Dr. George’s findings…• Decrease of activity in the regions of the cerebral cortex that are committed to forethought and planning.• These regions are in the temporal- parietal area of the cortex, located just over and a bit behind the ears, and the right prefrontal lobe, just behind the forehead.• The areas become even less active when volunteers received injections of morphine or cocaine.• Whilst the amygdala area activates during sadness, the structures change only slightly when a person is happy. The left amygdala seems to decrease activity, while the right amygdala increases activity.
In sum of happiness• Temporal-parietal• Right prefrontal lobe• Amygdala
V S Ha p yl e pe c on i tce f i h e V RIGHT HEMISPHERE c s– i s S • Negative emotions H
V S H a p y l e p e c o V n i t LEFT c f h HEMISPHERE e i e c s S• Positive emotions – i s H
Evidence?• Support for both… (Ley and Bryden, 1979; Reuter-Lorenz and Davidson, 1981; Natale et al., 1983; Reuter-Lorenz et al., 1983; McLaren and Bryson, 1987; Rodway et al., 2003)• Brain damaged patients:- In some, lesions to the right hemisphere impair the perception of emotion, regardless of the valence. (Adolphs et al., 1996; Borod et al., 1998; Adolphs et al., 2000)- In others, it was found that damage to the left hemisphere impairs the perception of +ive emotions while damage to the right impair perception of -ive emotions. (Borod et al., 1986; Mandal et al., 1991)• Chimeric studies on healthy participants
CHIMERIC FACES• Facial expression stimuli artificiallydesigned to project a different emotion toeach half of the brain simultaneously(Levy et al., 1972) •IDENTIFY THE EMOTION!