Dynamics of energy-efficient coding in visual cortex

Sparse coding enables cortical populations to represent sensory inputs efficiently, yet its temporal dynamics remain poorly understood. Here, we provide direct evidence that stimulus onset initially drives broad cortical activation, transiently reducing sparseness while increasing mutual information. Over time, competitive interactions refine the population response, maintaining high mutual information as activity declines and sparseness increases. Critically, coding efficiency, quantified as the ratio of mutual information to metabolic cost, steadily improves throughout stimulus presentation, revealing an active, time-dependent optimization of sensory representations.