Functional connectivity in a frontoparietal network involving the dorsal anterior cingulate cortex underlies decisions to accept a hypothesis.

Optimally interpreting our situations and experiences frequently requires comparing the evidence supporting conflicting hypotheses and deciding which to accept. This decision is comparable to an "Aha!" moment reached during insightful problem solving. We used a probabilistic reasoning task to investigate the neural activity underlying these processes. Participants rated the probability that a given focal hypothesis, rather than its alternative, was true. Decisions to accept the focal hypothesis elicited a stronger signal than decisions to reject it in a network involving the dorsal anterior cingulate cortex (dACC) and functionally connected frontal, parietal, and occipital regions. Follow-up analyses suggested that this was not simply a higher overall level of activation within the dACC or other individual regions of the network, but reflected a stronger signal for the network as a whole. This result is discussed in terms of functional connectivity between the dACC and other brain regions as a possible mechanism for coherence between components of a mental representation.