Theta coupling between V4 and prefrontal cortex predicts visual short-term memory performance
Short-term memory requires communication between multiple brain regions that collectively mediate the encoding and maintenance of sensory information. It has been suggested that oscillatory synchronization underlies intercortical communication. Yet, whether and how distant cortical areas cooperate during visual memory remains elusive. We examined neural interactions between visual area V4 and the lateral prefrontal cortex using simultaneous local field potential (LFP) recordings and single-unit activity (SUA) in monkeys performing a visual short-term memory task. During the memory period, we observed enhanced between-area phase synchronization in theta frequencies (3–9 Hz) of LFPs together with elevated phase locking of SUA to theta oscillations across regions. In addition, we found that the strength of intercortical locking was predictive of the animals' behavioral performance. This suggests that theta-band synchronization coordinates action potential communication between V4 and prefrontal cortex that may contribute to the maintenance of visual short-term memories. elevated phase locking of SUA to theta oscillations across regions. Most importantly, however, we show for the first time that the strength of inter-cortical locking is predictive of the animals’ memory performance. This suggests that theta-band synchronization may provide the basis for the timely coordination of spiking output between V4 and prefrontal cortex and may well reflect facilitated communication of visual information during visual memory.