EMOTIONAL ACTIVATION OF LIMBIC CIRCUITRY IN ELDERLY NORMAL SUBJECTS IN A PET STUDY

Objective: This study was undertaken to identify brain structures asso ciated with emotion in normal elderly subjects. Method: Eight normal s ubjects aged 55-78 years were shown film clips intended to provoke the emotions of happiness, fear, or disgust as well as a neutral state. D uring emotional activation, regional cerebral blood flow was measured with the use of [O-15]H2O positron emission tomography imaging, and su bjective emotional responses were recorded. Data were analyzed by subt racting the values during the neutral condition from the values in the various emotional activations. Results: The stimuli produced a genera l activation in visual pathways that included the primary and secondar y visual cortex, involving regions associated with object and spatial recognition. In addition, the specific emotions produced different reg ional limbic activations, which suggests that different pathways may b e used for different types of emotional stimuli. Conclusions: Emotiona l activation in normal elderly subjects was associated with increases in blood flow in limbic and paralimbic brain structures. Brain activat ion may be specific to the emotion being elicited but probably involve s complex sensory, association, and memory circuitry. Further studies are needed to identify activations that are specific for emotion.