Synchronization patterns reveal neuronal coding of working memory content
Fahimeh Mamashli,
Sheraz Khan,
Matti Hämäläinen,
Mainak Jas,
Tommi Raij,
Steven M. Stufflebeam,
Aapo Nummenmaa,
Jyrki Ahveninen
Affiliations
Fahimeh Mamashli
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Bldg. 149 13th Street, Charlestown, MA 02129, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
Sheraz Khan
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Bldg. 149 13th Street, Charlestown, MA 02129, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
Matti Hämäläinen
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Bldg. 149 13th Street, Charlestown, MA 02129, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
Mainak Jas
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Bldg. 149 13th Street, Charlestown, MA 02129, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
Tommi Raij
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Bldg. 149 13th Street, Charlestown, MA 02129, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; Departments of Physical Medicine and Rehabilitation and Neurobiology, Northwestern University, 710 North Lake Shore Drive, Chicago, IL 60611, USA
Steven M. Stufflebeam
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Bldg. 149 13th Street, Charlestown, MA 02129, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
Aapo Nummenmaa
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Bldg. 149 13th Street, Charlestown, MA 02129, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
Jyrki Ahveninen
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Bldg. 149 13th Street, Charlestown, MA 02129, USA; Department of Radiology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; Corresponding author
Summary: Neuronal oscillations are suggested to play an important role in auditory working memory (WM), but their contribution to content-specific representations has remained unclear. Here, we measure magnetoencephalography during a retro-cueing task with parametric ripple-sound stimuli, which are spectrotemporally similar to speech but resist non-auditory memory strategies. Using machine learning analyses, with rigorous between-subject cross-validation and non-parametric permutation testing, we show that memorized sound content is strongly represented in phase-synchronization patterns between subregions of auditory and frontoparietal cortices. These phase-synchronization patterns predict the memorized sound content steadily across the studied maintenance period. In addition to connectivity-based representations, there are indices of more local, “activity silent” representations in auditory cortices, where the decoding accuracy of WM content significantly increases after task-irrelevant “impulse stimuli.” Our results demonstrate that synchronization patterns across auditory sensory and association areas orchestrate neuronal coding of auditory WM content. This connectivity-based coding scheme could also extend beyond the auditory domain.
