Direct encoding of new visual concepts in early visual cortex.

Neocortical memories are assumed to rely on slow systems consolidation through hippocampal offline reactivation, with the exception of rapid integration of new information associated with prior knowledge in association cortex. Testing the scope of rapid neocortical learning, we tracked memory formation across 24 h with functional and diffusion-weighted MRI in subjects acquiring either conceptual or detailed knowledge of the same novel visual objects. Concept learning induced rapid within-session and 24h-stable changes in strength and pattern of functional responses in the early visual cortex. These were co-localized with microstructural changes, correlated positively with categorization performance and negatively with context recognition. Findings also indicate analogous changes of posterior parietal areas in detailed item-context learning. Thus, results show that rapid neocortical learning of information that is not meaningfully linked to prior knowledge occurs even in early sensory regions that process the corresponding visual features, suggesting that the potential for rapid learning is a fundamental property of the neocortex. The early onset of changes further substantiates the possibility of direct or parallel neocortical encoding without offline abstraction from individual episodes.