Task structure flexibly shifts working memory formats across cortical circuits

Abstract

Short-term memory in delayed-response tasks is widely attributed to choice-predictive activity in frontal cortex, maintained by discrete attractor dynamics in thalamocortical circuits. Here we ask whether this mechanism extends to tasks where cues specify goals rather than actions. We trained rats on two auditory delayed-response tasks: an egocentric task, where cues mapped to movement directions, and an allocentric task, where cues specified world-centered locations. Using electrophysiology and optogenetics, we found that the egocentric task engaged early sensorimotor transformation and prospective motor planning in secondary motor cortex (M2). The allocentric task, however, relied on a delayed sensorimotor transformation: auditory cortex carried a retrospective sensory trace, whereas M2 neither encoded choice nor was required for its maintenance during the delay. Simplifying the allocentric task to a single start position rapidly reinstated early transformation and M2 dependence within the same animals. These results demonstrate that animals flexibly select the timing of sensorimotor transformation, and that this choice determines the format and cortical locus of working memory.