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OBJECTIVE: Positron emission tomography was used to investigate the neural substrates of normal human emotional and their dependence on the types of emotional stimulus. METHOD: Twelve healthy female subjects underwent 12 measurements of regional brain activity following the intravenous bolus administration of [15O]H2O as they alternated between emotion-generating and control film and recall tasks. Automated image analysis techniques were used to characterize and compare the increases in regional brain activity associated with the emotional response to complex visual (film) and cognitive (recall) stimuli. RESULTS: Film- and recall-generated emotion were each associated with significantly increased activity in the vicinity of the medial prefrontal cortex and thalamus, suggesting that these regions participate in aspects of emotion that do not depend on the nature of the emotional stimulus. Film-generated emotion was associated with significantly greater increases in activity bilaterally in the occipitotemporparietal cortex, lateral cerebellum, hypothalamus, and a region that includes the anterior temporal cortex, amygdala, and hippocampal formation, suggesting that these regions participate in the emotional response to certain exteroceptive sensory stimuli. Recall-generated sadness was associated with significantly greater increases in activity in the vicinity of the anterior insular cortex, suggesting that this region participates in the emotional response to potentially distressing cognitive or interoceptive sensory stimuli. CONCLUSIONS: While this study should be considered preliminary, it identified brain regions that participate in externally and internally generated human emotion.
OBJECTIVE: Happiness, sadness, and disgust are three emotions that differ in their valence (positive or negative) and associated action tendencies (approach or withdrawal). This study was designed to investigate the neuroanatomical correlates of these discrete emotions. METHOD: Twelve healthy female subjects were studied. Positron emission tomography and [15O]H2O were used to measure regional brain activity. There were 12 conditions per subject: happiness, sadness, and disgust and three control conditions, each induced by film and recall. Emotion and control tasks were alternated throughout. Condition order was pseudo-randomized and counterbalanced across subjects. Analyses focused on brain activity patterns for each emotion when combining film and recall data. RESULTS: Happiness, sadness, and disgust were each associated with increases in activity in the thalamus and medial prefrontal cortex (Brodmann's area 9). These three emotions were also associated with activation of anterior and posterior temporal structures, primarily when induced by film. Recalled sadness was associated with increased activation in the anterior insula. Happiness was distinguished from sadness by greater activity in the vicinity of ventral mesial frontal cortex. CONCLUSIONS: While this study should be considered preliminary, it identifies regions of the brain that participate in happiness, sadness, and disgust, regions that distinguish between positive and negative emotions, and regions that depend on both the elicitor and valence of emotion or their interaction.
Recent evidence suggests that frontal brain electrical activity reveals asymmetries in activation in response to positive vs negative affective stimuli. This study was designed to evaluate whether this asymmetry is present at birth. Newborn infants were presented with water followed by a sucrose solution and then by a citric acid solution. Facial expression was videotaped during the presentation of the liquids and EEG was recorded from the frontal and parietal scalp regions on the left and right side. Usable EEG data were obtained from 16 newborn infants in response to these taste conditions. Videotaping of facial expression in response to these stimuli indicated the presence of disgust during both water (the first taste introduced) and citric acid. EEG was Fourier Transformed and power in the 1-3, 3-6 and 6-12 Hz bands was computed. The findings revealed that the water condition produced reductions in right-hemisphere power in the two higher frequency bands in both the scalp regions compared with the other two conditions. The sucrose condition produced greater relative left-sided activation in both regions compared with the water condition. These data, in conjunction with our previous findings of asymmetries in 10-month-old infants, indicate that stimulus-elicited affective asymmetries in brain electrical activity are present at birth.