Toward a cumulative science of functional integration: A meta‐analysis of psychophysiological interactions

Abstract

Much of the work in cognitive neuroscience is shifting from a focus on single brain regions to a focus on the connectivity between multiple brain regions. These inter-regional connectivity patterns contribute to a wide range of behaviors and are studied with models of functional integration. The rapid expansion of the literature on functional integration offers an opportunity to scrutinize the consistency and specificity of one of the most popular approaches for quantifying connectivity: psychophysiological interaction (PPI) analysis. We performed coordinate-based meta-analyses on 284 PPI studies, which allowed us to test a) whether those studies consistently converge on similar target regions and b) whether the identified target regions are specific to the chosen seed region and psychological context. Our analyses revealed two key results. First, we found that different types of PPI studies—e.g., those using seeds such as amygdala and dorsolateral prefrontal cortex (DLPFC) and contexts such as emotion and cognitive control, respectively—each consistently converge on similar target regions, thus supporting the reliability of PPI as a tool for studying functional integration. Second, we also found target regions that were specific to the chosen seed region and psychological context, indicating distinct patterns of brain connectivity. For example, the DLPFC seed reliably contributed to a posterior cingulate cortex target during cognitive control but contributed to an amygdala target in other contexts. Our results point to the robustness of PPI while highlighting common and distinct patterns of functional integration, potentially advancing models of brain connectivity.

Meta‐analysis of psychophysiological interactions: Revisiting cluster‐level thresholding and sample sizes

“…For example, PPI studies using the dorsolateral prefrontal cortex (DLPFC) as a seed region identified targets in the posterior cingulate cortex when the psychological context involved cognitive control and targets in the amygdala when the psychological context did not involve cognitive control. These results highlight both the consistency and specificity of PPI studies (Smith, et al, 2016). …”

“…In recent study, we addressed this problem by conducting CMBAs on studies examining psychophysiological interactions (PPI), a popular brain connectivity analysis approach that can be interpreted as a simple (linear) model of effective connectivity (Smith, et al, 2016). PPI evaluates whether an interaction between a seed region and psychological context is expressed in a target region (Friston et al, 1997).…”

Reward Sensitivity Enhances Ventrolateral Prefrontal Cortex Activation during Free Choice

“…This finding yields a potential interpretation that free choice enhances VLPFC region connectivity with target PCC and precentral regions to support motor responses in reward sensitive individuals. A recent meta-analysis of PPI studies found PCC was a reliable target of studies examining cognitive control, but only when the dorsolateral prefrontal cortex was used as the seed region (Smith et al, 2016a). This discrepancy could be due to the fact that our results are based on individual differences in reward sensitivity, which were explicitly ignored in the recent PPI meta-analysis.…”

“…Recent meta-analytic work has demonstrated that PPI produces consistent and specific patterns of task-dependent brain connectivity across studies (Smith and Delgado, 2016; Smith et al, 2016a). For each individual, we extracted BOLD time-series from the peak voxel within a mask of the VLPFC cluster.…”

The behavioral and neural basis of empathic blame

“…Exploratory functional connectivity analysis. Exploratory functional connectivity was carried out using standardized psychophysiological interaction (sPPI) analysis [56][57][58] . Specifically, we explored which brain regions showed changes in information exchange with the areas involved in decisions about blame (versus acceptability) for accidental harm cases.…”