A gradient from long-term memory to novel cognition: graded transitions through default mode and executive cortex

Human cognition flexibly guides decision-making in familiar and novel situations. Although these decisions are often treated as dichotomous, in reality, situations are neither completely familiar, nor entirely new. Contemporary accounts of brain organization suggest that neural function is organized along a gradient from unimodal regions of sensorimotor cortex, through executive regions to transmodal default network. We examined whether this graded view of neural organization helps to explain how decision-making changes across situations that vary in their alignment with long-term knowledge. Functional magnetic resonance imaging found that as decisions are made in an increasingly familiar context, the BOLD signal follows this neural gradient, with stronger responses in default regions when items are linked in long-term memory. In this way, neural organization is optimized to support decision-making in both highly familiar and less familiar situations.