Final Report Summary - EMOTION AND CONTROL (The Effects of Emotion on Top-Down Prioritization Among Younger and Older Adults)
Our everyday surroundings provide an overwhelming amount of information. In contrast, our processing resources are limited. Therefore, it is critical to prioritise important information while inhibiting distracting information. This prioritisation process is important especially when encountering a situation or stimulus which is important for survival and feeling emotional arousal. How does then emotional arousal influence goal-based cognitive processing?
Previous research on this issue provides a confusing set of results. On the one hand, much research suggests that emotional events disrupt concurrent working memory performance (Dolcos & McCarthy, 2006), suggesting that arousal induced by emotional events impairs top-down cognitive processing. However, other researchers suggest the opposite patterns (Kanske & Kotz, 2011; Yuen et al., 2009). The current project aims to address this inconsistency and tests the hypothesis that emotional arousal has different effects on cognitive processing depending on information’s top-down priority.
The first goal of the project is to probe the interaction between emotional arousal and top-down priority in cognitive processing by behavioural studies. Based on recently proposed theories (Mather & Sutherland, 2011), we hypothesised that emotional arousal enhances goal-directed processing when top-down signal is strongly established, whereas arousal impairs goal-directed processing when top-down signal is only weakly developed at the time of the onset of arousal. We tested this prediction by manipulating top-down goal signals in three ways: top-down goal, prior memory and expectation. Across all studies, we found that emotional arousal has different effects on perception and memory depending on information’s top-down priority signals. Specifically, emotional arousal enhances processing of high-priority information but impairs processing of low-priority information.
The second goal of the project was to provide insights into the brain mechanisms by which arousal interacts with top-down priority in modulating cognitive processing. To address this second goal, we reviewed previous relevant literatures and proposed the Glutamate Amplifies Noradrenergic Effects (GANE) model to explain the brain mechanisms by which arousal influences cognitive processing differently depending on priority. This theory suggests that noradrenaline plays key roles in enabling the selective effects of emotional arousal on cognitive processing. We next developed a computational model based on this model and tested whether GANE can reproduce the results from our behavioural studies mentioned above.
The third goal of the project was to test the interaction between priority and emotional arousal in older adults. We ran a behavioural study to test the interaction between emotional arousal and goal-relevance but found that top-down goal manipulations did not have strong effects in older adults. In a subsequent neuroimaging study, we then found that while arousal enhances activation in the front-parietal network in younger adults, this enhancement effect was not observed in older adults. Since the front-parietal network is important for processing of goal-relevant information, these results suggest that arousal enhances top-down prioritisation via enhancing the front-parietal network in younger adults but not in older adults. The lack of the arousal's enhancement effects for the front-parietal network in older adults can be due to the age-related decline in this network observed in our other studies. In addition, we applied our computational model and found that age-related impairments in the norepinephrine reuptake process and GABAergic process may also play roles.
In summary, findings from the current project suggest that emotional arousal always neither impairs nor facilitates cognitive processing. Instead, it appears that emotional arousal interacts with top-down priority, such as goal-relevance and prior memory, in modulating cognitive processing in younger adults. Our theoretical and computational models further suggest that the priority-by-arousal interaction is supported by the effects of noradrenaline in the brain. In contrast, the interaction between arousal and goal-relevance is much weaker in older adults presumably due to the impaired front-parietal network in older adults. This suggests that older adults may have a particular problem with when they face emotional situations and want to focus on something important.
Previous research on this issue provides a confusing set of results. On the one hand, much research suggests that emotional events disrupt concurrent working memory performance (Dolcos & McCarthy, 2006), suggesting that arousal induced by emotional events impairs top-down cognitive processing. However, other researchers suggest the opposite patterns (Kanske & Kotz, 2011; Yuen et al., 2009). The current project aims to address this inconsistency and tests the hypothesis that emotional arousal has different effects on cognitive processing depending on information’s top-down priority.
The first goal of the project is to probe the interaction between emotional arousal and top-down priority in cognitive processing by behavioural studies. Based on recently proposed theories (Mather & Sutherland, 2011), we hypothesised that emotional arousal enhances goal-directed processing when top-down signal is strongly established, whereas arousal impairs goal-directed processing when top-down signal is only weakly developed at the time of the onset of arousal. We tested this prediction by manipulating top-down goal signals in three ways: top-down goal, prior memory and expectation. Across all studies, we found that emotional arousal has different effects on perception and memory depending on information’s top-down priority signals. Specifically, emotional arousal enhances processing of high-priority information but impairs processing of low-priority information.
The second goal of the project was to provide insights into the brain mechanisms by which arousal interacts with top-down priority in modulating cognitive processing. To address this second goal, we reviewed previous relevant literatures and proposed the Glutamate Amplifies Noradrenergic Effects (GANE) model to explain the brain mechanisms by which arousal influences cognitive processing differently depending on priority. This theory suggests that noradrenaline plays key roles in enabling the selective effects of emotional arousal on cognitive processing. We next developed a computational model based on this model and tested whether GANE can reproduce the results from our behavioural studies mentioned above.
The third goal of the project was to test the interaction between priority and emotional arousal in older adults. We ran a behavioural study to test the interaction between emotional arousal and goal-relevance but found that top-down goal manipulations did not have strong effects in older adults. In a subsequent neuroimaging study, we then found that while arousal enhances activation in the front-parietal network in younger adults, this enhancement effect was not observed in older adults. Since the front-parietal network is important for processing of goal-relevant information, these results suggest that arousal enhances top-down prioritisation via enhancing the front-parietal network in younger adults but not in older adults. The lack of the arousal's enhancement effects for the front-parietal network in older adults can be due to the age-related decline in this network observed in our other studies. In addition, we applied our computational model and found that age-related impairments in the norepinephrine reuptake process and GABAergic process may also play roles.
In summary, findings from the current project suggest that emotional arousal always neither impairs nor facilitates cognitive processing. Instead, it appears that emotional arousal interacts with top-down priority, such as goal-relevance and prior memory, in modulating cognitive processing in younger adults. Our theoretical and computational models further suggest that the priority-by-arousal interaction is supported by the effects of noradrenaline in the brain. In contrast, the interaction between arousal and goal-relevance is much weaker in older adults presumably due to the impaired front-parietal network in older adults. This suggests that older adults may have a particular problem with when they face emotional situations and want to focus on something important.