Amygdala response to emotional stimuli without awareness: Facts and Interpretations

M. Diano, A. Celeghin, Arianna Bagnis, M. Tamietto

Research output: Contribution to journalArticleScientificpeer-review

67 Citations (Scopus)
157 Downloads (Pure)

Abstract

Over the past two decades, evidence has accumulated that the human amygdala exerts some of its functions also when the observer is not aware of the content, or even presence, of the triggering emotional stimulus. Nevertheless, there is as of yet no consensus on the limits and conditions that affect the extent of amygdalas response without focused attention or awareness. Here we review past and recent studies on this subject, examining neuroimaging literature on healthy participants as well as brain-damaged patients, and we comment on their strengths and limits. We propose a theoretical distinction between processes involved in attentional unawareness, wherein the stimulus is potentially accessible to enter visual awareness but fails to do so because attention is diverted, and in sensory unawareness, wherein the stimulus fails to enter awareness because its normal processing in the visual cortex is suppressed. We argue this distinction, along with data sampling amygdala responses with high temporal resolution, helps to appreciate the multiplicity of functional and anatomical mechanisms centered on the amygdala and supporting its role in non-conscious emotion processing. Separate, but interacting, networks relay visual information to the amygdala exploiting different computational properties of subcortical and cortical routes, thereby supporting amygdala functions at different stages of emotion processing. This view reconciles some apparent contradictions in the literature, as well as seemingly contrasting proposals, such as the dual stage and the dual route model. We conclude that evidence in favor of the amygdala response without awareness is solid, albeit this response originates from different functional mechanisms and is driven by more complex neural networks than commonly assumed. Acknowledging the complexity of such mechanisms can foster new insights on the varieties of amygdala functions without awareness and their impact on human behavior.

Original languageEnglish
Article number2029
Number of pages13
JournalFrontiers in Psychology
Volume7
DOIs
Publication statusPublished - 2017

Keywords

  • amygdala
  • attention
  • hemispatial neglect
  • blindsight
  • fMRI neuroimaging
  • superior colliculus
  • pulvinar
  • conscious perception
  • EVENT-RELATED FMRI
  • NON-CONSCIOUS RECOGNITION
  • HAPPY FACIAL EXPRESSIONS
  • FEAR-POTENTIATED STARTLE
  • PRIMARY VISUAL-CORTEX
  • AFFECTIVE BLINDSIGHT
  • SUPERIOR COLLICULUS
  • BODY LANGUAGE
  • BODILY EXPRESSIONS
  • BINOCULAR-RIVALRY

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