Learning multiple concurrent higher-order visual sequences in human primary visual cortex

Learning and memory are known to be supported by a network involving the medial temporal lobe and linked neocortical regions. Emerging evidence indicates that primary sensory regions (i.e., V1) may be also contribute to recognition memory processes, but this has been only tested with a single visuospatial sequence as the target memorandum. The present study used functional magnetic resonance imaging to test the capacity of human V1 to support the learning of multiple, concurrent and complex visual sequences involving discontinous (second-order) associations. Two peripheral, task-irrelevant but structured sequences of orientated gratings appeared simultaneously in right and left visual fields alongside a central, task-relevant sequence that was in the focus of spatial attention. Pseudorandom sequences were interspersed amongst the three complex structured sequences with different asynchronies. We found that a network involving the precuneus and V1 was involved in learning the structured sequence presented at central fixation, whereas right V1 was modulated by repeated exposure to a concurrent structured sequence presented in the left visual field. The same result was not found in left V1. These results indicate that human V1 can support the learning of multiple concurrent sequences involving complex discontinuous inter-item associations, even those that are goal-irrelevant.