Temporal Gating by Chandelier Cells Encodes Signed Prediction Errors

The brain refines its predictions of the world by updating its internal model whenever sensory input differs from expectation. The sign of this prediction error matters: an unexpected event signals that the model under-predicted (positive error), while a predicted event that fails to occur indicates that the model over-predicted (negative error), and the two should drive opposite synaptic changes. How cortical circuits represent error sign in spiking activity, and how that representation translates into synaptic learning, remain unresolved. We propose the Signed Error by Timing Asymmetry (SETA) model, in which the sign of a prediction error is encoded by when layer 2/3 neurons fire relative