Learning to infer transitively on a mental line in premotor cortex.

Dorsal premotor cortex (PMd) encodes a mental line during transitive inference in monkeys, with activity organizing along a predicted direction and supporting a geometrical model.

• Why it matters: Understanding the neural basis of transitive inference can shed light on how the brain performs deductive reasoning and learns complex relationships, which remains largely unclear.
• What they did: The study recorded multiunit activity in the PMd of monkeys as they learned item relationships for motor decisions, revealing the organization and rotation of the mental line during learning.
• The result: Findings suggest that PMd activity supports a geometrical model of transitive inference, with the mental line rotating to align with motor planning, advancing knowledge of neural mechanisms underlying reasoning.