Ekman (Ekman, 1992) developed the Directed Facial Action Task (DFAT), which demonstrated that facial expressions can elicit emotional physiology. The present study investigated whether these responses also have mood-congruent memory effects, as found when emotions are elicited in other ways. 38 participants performed the DFAT for happy and sad expressions before recalling neutral, positive and negative images. The mood-congruent memory hypothesis predicts that, if the DFAT produces sustained affect, participants should recall more mood-congruent than mood-incongruent images. Some participants performed the DFAT while Galvanic Skin Response, an index of autonomic emotional response, was recorded. GSR correlated with reported mood change in the happy condition, while the difference between mood-congruent and –incongruent memory correlated with reported mood change in the sad condition. However, there was no correlation between GSR and memory. These results show that self-reported emotion but not physiological response was linked to congruency effects in memory for emotional images.
The inferior frontal gyrus and inferior parietal lobe have been characterized as human homologues of the monkey “mirror neuron” system, critical for both action production and recognition. However, data from brain lesion patients with selective impairment on only one of these tasks provides evidence of neural and cognitive dissociations. We sought to clarify the relationship between action production (AP) and action recognition (AR), and their critical neural substrates, by directly comparing performance of 131 chronic left-hemisphere stroke patients on both tasks—to our knowledge, the largest lesion-based experimental investigation of action cognition to date. Using voxel-based lesion-symptom mapping (VLSM), we found that lesions to primary motor and somatosensory cortices and inferior parietal lobule were associated with disproportionately impaired performance on AP, while lesions to lateral temporal-occipital cortex (LTO) were associated with a relatively rare pattern of disproportionately impaired performance on AR. In contrast, damage to posterior middle temporal gyrus (pMTG) was associated with impairment on both AP and AR. The distinction between LTO, critical for recognition, and pMTG, important for both tasks, suggests a rough gradient from modality-specific to abstract representations in posterior temporal cortex, the first lesion-based evidence for this phenomenon. Overall, the results of this large patient study help to bring closure to a long-standing debate by showing that tool-related action production and recognition critically depend on both common and distinct left hemisphere neural substrates, most of which are external to putative human mirror regions.