Emotion-Attention Interaction in the Right Hemisphere

Hemispheric asymmetries in affective and cognitive functions have been extensively studied. While both cerebral hemispheres contribute to most affective and cognitive processes, neuroscientific literature and neuropsychological evidence support an overall right hemispheric dominance for emotion, attention and arousal. Emotional stimuli, especially those with survival value such as threat, tend to be prioritized in attentional resource competition. Arousing unpleasant emotional stimuli have prioritized access, especially to right-lateralized attention networks. Interference of task performance may be observed when limited resources are exhausted by task- and emotion-related processing. Tasks that rely on right hemisphere-dependent processing, like attending to the left visual hemifield or global-level visual features, are especially vulnerable to interference due to attention capture by unpleasant emotional stimuli. The aim of this review is to present literature regarding the special role of the right hemisphere in affective and attentional brain processes and their interaction. Furthermore, clinical and technological implications of this interaction will be presented. Initially, the effects of focal right hemisphere lesion or atrophy on emotional functions will be introduced. Neurological right hemisphere syndromes including aprosodia, anosognosia and neglect, which further point to the predominance of the intact right hemisphere in emotion, attention and arousal will be presented. Then there will be a brief review of electrophysiological evidence, as well as evidence from patients with neglect that support attention capture by emotional stimuli in the right hemisphere. Subsequently, experimental work on the interaction of emotion, attention and cognition in the right hemispheres of healthy subjects will be presented. Finally, clinical implications for better understanding and assessment of alterations in emotion-attention interaction due to brain disorder or treatment, such as neuromodulation, that impact affective brain functions will be discussed. It will be suggested that measuring right hemispheric emotion-attention interactions may provide basis for novel biomarkers of brain health. Such biomarkers allow for improved diagnostics in brain damage and disorders and optimized treatments. To conclude, future technological applications will be outlined regarding brain physiology-based measures that reflect engagement of the right hemisphere in affective and attentional processes.

Emotional content overrides spatial attention

Spatial attention is our capacity to attend to or ignore particular regions of our spatial environment. However, some classes of stimuli may be able to override our efforts to ignore them. Here we assessed the relationship between involuntary attentional capture with emotional images and spatial attention at early stages of perceptual processing. Multiple scenes of unpleasant and neutral content were displayed in rapid serial visual presentation (RSVP) streams that elicited the steady-state visual evoked potential (SSVEP), a neural marker of selective attention at early visual areas. In a spatial cueing task, participants were cued to covertly attend to RSVP streams presented at 4 and 6 Hz presentation rates in the left and right visual hemifields. The task was to detect square targets occasionally displayed within the image streams, responding only to those appearing on the cued side. The RSVP streams were always neutral pictures in one visual hemifield but would unpredictably switch from neutral to aversive content in the other visual hemifield. We found that SSVEP amplitude was consistently modulated by a change in emotional valence of image streams, regardless of whether the change in content occurred in the attended or unattended spatial location, reflecting an automatic sensory amplification for affective stimuli. The present data provide further evidence in support that emotional images can attract visual processing resources independently of spatial attention allocation, and are consistent with sustained sensory facilitation of early visual areas through re-entrant feedback projections from higher-order cortical areas involved in the extraction of affective information.