Architecture of explanatory inference in the human prefrontal cortex

Abstract

Causal reasoning is a ubiquitous feature of human cognition. We continuously seek to understand, at least implicitly and often explicitly, the causal scenarios in which we live, so that we may anticipate what will come next, plan a potential response and envision its outcome, decide among possible courses of action in light of their probable outcomes, make midstream adjustments in our goal-related activities as our situation changes, and so on. A considerable body of research shows that the lateral prefrontal cortex (PFC) is crucial for causal reasoning, but also that there are significant differences in the manner in which ventrolateral PFC, dorsolateral PFC, and anterolateral PFC support causal reasoning. We propose, on the basis of research on the evolution, architecture, and functional organization of the lateral PFC, a general framework for understanding its roles in the many and varied sorts of causal reasoning carried out by human beings. Specifically, the ventrolateral PFC supports the generation of basic causal explanations and inferences; dorsolateral PFC supports the evaluation of these scenarios in light of some given normative standard (e.g., of plausibility or correctness in light of real or imagined causal interventions); and anterolateral PFC supports explanation and inference at an even higher level of complexity, coordinating the processes of generation and evaluation with further cognitive processes, and especially with computations of hedonic value and emotional implications of possible behavioral scenarios - considerations that are often critical both for understanding situations causally and for deciding about our own courses of action.

Keywords: causal reasoning; executive control; explanatory inference; lateral prefrontal cortex.

Figure 1

Brodmann map of the lateral PFC. Reproduced with permission from Ramnani and Owen (2004).

Figure 2

Integrative anatomy of the macaque monkey PFC. Numbers refer to subregions within the lateral PFC defined by Brodmann. Modified with permission from Miller (2000).

Figure 3

Ontogenetic map of the prefrontal cortex according to Flechsig (1901, 1920). The numeration of the areas indicates the order of their myelination. Modified with permission from Flechsig (1920).

Figure 4

Neural architecture of explanatory inference. (A) Summarizes the functional organization of the lateral PFC, and (B–D) illustrate supportive evidence.