Formation and Reverberation of Sequential Neural Activity Patterns Evoked by Sensory Stimulation Are Enhanced during Cortical Desynchronization

Memory formation is hypothesized to involve the generation of event-specific neural activity patterns during learning and the subsequent spontaneous reactivation of these patterns. Here, we present evidence that these processes can also be observed in urethane-anesthetized rats and are enhanced by desynchronized brain state evoked by tail pinch, subcortical carbachol infusion, or systemic amphetamine administration. During desynchronization, we found that repeated tactile or auditory stimulation evoked unique sequential patterns of neural firing in somatosensory and auditory cortex and that these patterns then reoccurred during subsequent spontaneous activity, similar to what we have observed in awake animals. Furthermore, the formation of these patterns was blocked by an NMDA receptor antagonist, suggesting that the phenomenon depends on synaptic plasticity. These results suggest that anesthetized animals with a desynchronized brain state could serve as a convenient model for studying stimulus-induced plasticity to improve our understanding of memory formation and replay in the brain. •Sensory stimulation evokes sequential activity patterns in sensory cortex•These patterns reoccur during subsequent spontaneous activity•Formation of new spiking patterns is facilitated in desynchronized brain state•In anesthetized rats, desynchronized brain state can be induced by amphetamine Sensory experience evokes stimulus-specific patterns of neuronal activity. These patterns are later spontaneously replayed, which is believed to be an important part of memory formation and learning. Bermudez Contreras et al. show that these processes are enhanced in attentive-like brain state.