title: Positive facial affect - an fMRI study on the involvement of insula and amygdala.
abstract: Imitation of facial expressions engages the putative human mirror neuron system as well as the insula and the amygdala as part of the limbic system. The specific function of the latter two regions during emotional actions is still under debate. The current study investigated brain responses during imitation of positive in comparison to non-emotional facial expressions. Differences in brain activation of the amygdala and insula were additionally examined during observation and execution of facial expressions. Participants imitated, executed and observed happy and non-emotional facial expressions, as well as neutral faces. During imitation, higher right hemispheric activation emerged in the happy compared to the non-emotional condition in the right anterior insula and the right amygdala, in addition to the pre-supplementary motor area, middle temporal gyrus and the inferior frontal gyrus. Region-of-interest analyses revealed that the right insula was more strongly recruited by (i) imitation and execution than by observation of facial expressions, that (ii) the insula was significantly stronger activated by happy than by non-emotional facial expressions during observation and imitation and that (iii) the activation differences in the right amygdala between happy and non-emotional facial expressions were increased during imitation and execution, in comparison to sole observation. We suggest that the insula and the amygdala contribute specifically to the happy emotional connotation of the facial expressions depending on the task. The pattern of the insula activity might reflect increased bodily awareness during active execution compared to passive observation and during visual processing of the happy compared to non-emotional facial expressions. The activation specific for the happy facial expression of the amygdala during motor tasks, but not in the observation condition, might reflect increased autonomic activity or feedback from facial muscles to the amygdala.
authors.affiliation: Department of Psychiatry, Psychotherapy, and Psychosomatics, Rheinisch-Westfälische Technische Hochschule Aachen University, Aachen, Germany ; Central Service Facility "Functional Imaging" at the Interdisciplinary Center for Clinical Research, Rheinisch-Westfälische Technische Hochschule Aachen University, Aachen, Germany ; Jülich Aachen Research Alliance - Translational Brain Medicine, Jülich/Aachen, Germany ; Department of Neurology, Rheinisch-Westfälische Technische Hochschule Aachen University, Aachen, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Pohl
authors.forename: Silke
authors.initials: S
authors.lastname: Anders
authors.forename: Martin
authors.initials: M
authors.lastname: Schulte-Rüther
authors.forename: Klaus
authors.initials: K
authors.lastname: Mathiak
authors.forename: Tilo
authors.initials: T
authors.lastname: Kircher
mesh_terms: D000328:Adult; D000339:Affect / Q000502:physiology*; D000679:Amygdala / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000502:physiology*; D004644:Emotions; D005149:Facial Expression; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D059167:Mirror Neurons / Q000502:physiology; D009415:Nerve Net; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult