Publications Repository - Gdańsk University of Technology

Processing of memory is supported by coordinated activity in a network of sensory, association, and motor brain regions. It remains a major challenge to determine where memory is encoded for later retrieval. Here we used direct intracranial brain recordings from epilepsy patients performing free recall tasks to determine the temporal pattern and anatomical distribution of verbal memory encoding across the entire human cortex. High gamma frequency activity (65-115 Hz) showed consistent power responses during encoding of subsequently recalled and forgotten words on a subset of electrodes localized in 16 distinct cortical areas activated in the tasks. More of the high gamma power during word encoding, and less power before and after the word presentation, was characteristic of successful recall and observed across multiple brain regions. Latencies of the induced power changes and this subsequent memory effect between the recalled and forgotten words followed an anatomical sequence from visual to prefrontal cortical areas. Finally, the magnitude of the memory effect was unexpectedly found to be the largest in selected brain regions both at the top and at the bottom of the processing stream. These included the language processing areas of the prefrontal cortex and the downstream visual areas at the junction of the occipital and temporal lobes. Our results provide evidence for distributed encoding of verbal memory organized along a hierarchical posterior-to-anterior processing stream.

Authors

• dr Michał Tomasz Kucewicz link open in new tab ,
• Krishnakant Saboo,
• Brent M. Berry,
• Vaclav Kremen,
• Laura R. Miller,
• Fatemeh Khadjevand,
• Cory S. Inman,
• Paul A. Wanda,
• Michael R. Sperling,
• Richard Gorniak,
• Kathryn A. Davis,
• Barbara C. Jobst,
• Bradley Lega,
• Sameer A. Sheth,
• Daniel S. Rizzuto,
• Ravishankar K Iyer,
• Michael J. Kahana,
• Gregory A. Worrell