Functional magnetic resonance imaging of temporally distinct responses to emotional facial expressions

Abstract

Understanding the temporal dynamics of brain function contributes to models of learning and memory as well as the processing of emotions and habituation. In this article, we present a novel analysis technique to investigate spatiotemporal patterns of activation in response to blocked presentations of emotional stimuli. We modeled three temporal response functions (TRFs), which were maximally sensitive to the onset, early or sustained temporal component of a given block type. This analysis technique was applied to a data set of 29 subjects who underwent functional magnetic resonance imaging while responding to fearful, happy, and sad facial expressions. We identified brain regions that uniquely fit each of the three TRFs for each emotional condition and compared the results to the standard approach, which was based on the canonical hemodynamic response function. We found that voxels within the precuneus fit the onset TRF but did not fit the early or the sustained TRF in all the emotional conditions. On the other hand, voxels within the amygdala fit the sustained TRF, but not the onset or early TRF, during presentation of fearful stimuli, suggesting a spatiotemporal dissociation between these structures. This technique provides researchers with an additional tool in order to investigate the temporal dynamics of neural circuits.

Diverting Attention Suppresses Human Amygdala Responses to Faces

“…It has been suggested that these inconsistencies likely reflect methodological differences in the temporal parameters as the studies varied in the length of blocks and experimental runs. It has been proposed that the amygdala does not exhibit habituation when shorter (e.g., 18 s) blocks are used (Haas et al, 2008 ), which is consistent with our data and design (one block lasted 20 s).…”

“…Our findings differ from previously reported data (Phillips et al, 2001 ; Fischer et al, 2003 ; Williams et al, 2004 ) as we did not observe a rapid habituation of the amygdala to repeatedly presented emotional stimuli thereby disproving the idea that the signal decrease could be attributed to habituation. Supporting our results, a recent study (Haas et al, 2008 ) also failed to find any evidence for amygdala habituation. It has been suggested that these inconsistencies likely reflect methodological differences in the temporal parameters as the studies varied in the length of blocks and experimental runs.…”

Decoding Unattended Fearful Faces with Whole-Brain Correlations: An Approach to Identify Condition-Dependent Large-Scale Functional Connectivity

“…This is not inconsistent with the observation in a recent meta-analysis that amygdala activity was significantly greater for explicit (attended) fear perception vs. implicit fear perception [34]. In addition, the finding that amygdala demonstrates a distinct temporal profile from other structures during emotional face processing could also explain why more functional connections with amygdala were not observed in the current analysis [10]. Instead, the structure which contributed the most in discriminating between the fear and neutral conditions was thalamus (Fig.…”

Effects of mindful-attention and compassion meditation training on amygdala response to emotional stimuli in an ordinary, non-meditative state

“…This mixed block/event-related design was chosen to allow the BOLD signal to return to baseline between images, which increases functional signal-to-noise ratio, statistical power, and robustness of the results (Amaro and Barker, 2006). The duration of each block was short enough to prevent habituation in the amygdala (Haas et al, 2009). To prevent unintentional influences on the study participants, which may have confounded our results, the experimenters (GD and ELS) were blinded with respect to subjects' group assignment until after the end of the post-intervention fMRI experiment.…”