Emotions evoke a profound modulation of human cognition. Emotional events are susceptible to preferential perceptual processing and are more likely to be remembered than neutral ones. But how does the emotionality of a stimulus lead to enhanced perception and memory? The series of experiments proposed will investigate the underlying human neurobiological mechanisms by which emotion modulates these two cognitive processes. This will proceed through the integration of basic psychological tasks, human psychopharmacology and an examination of functional neuronal measures in humans, employing intracranial EEG recordings from patients with depth electrodes, magneto-encephalography (MEG) and functional magnetic resonance imaging (fMRI). The core hypothesis is that emotions evoke an amygdala-dependent modulation of other brain areas; higher-order visual cortex and hippocampus for effects on perception and memory, respectively. A central theme is that the noradrenergic (NA) system is critical for this interplay between different brain areas. Emotions can also evoke deleterious effects on memory, particularly for stimuli that precede the emotional event, but the mechanisms underlying this are also poorly understood. Initial experiments presented here will characterise the temporal profile of this retrograde amnesia, as well as the neuro-physiological and biochemical correlates. The next study, to be performed in the context of simultaneous EEG-fMRI recordings, tests whether response inhibition-induced associative memory impairment has a NA basis.
A final study examines how the spatial frequency of emotional stimuli modulates both perceptual and memory-related neuronal activity in healthy controls and patients with depression, a condition characterised by abnormal emotional processing. Thus, by employing a combination of neuroscience techniques, the proposed studies will address a number of critical, outstanding questions regarding the way in which emotion modulates cognition.